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1

Quantum chromodynamics with advanced computing  

SciTech Connect (OSTI)

We survey results in lattice quantum chromodynamics from groups in the USQCD Collaboration. The main focus is on physics, but many aspects of the discussion are aimed at an audience of computational physicists.

Kronfeld, Andreas S.; /Fermilab

2008-07-01T23:59:59.000Z

2

High Energy Resummation in Quantum Chromo–Dynamics   

E-Print Network [OSTI]

In this thesis I discuss different aspects of high energy resummation in Quantum Chromo-Dynamics and its relevance for precision physics at hadron colliders. The high energy factorisation theorem is presented and discussed ...

Marzani, Simone

2008-01-01T23:59:59.000Z

3

Light-front quantum chromodynamics: A framework for the analysis of hadron physics  

SciTech Connect (OSTI)

An outstanding goal of physics is to find solutions that describe hadrons in the theory of strong interactions, Quantum Chromodynamics (QCD). For this goal, the light-front Hamiltonian formulation of QCD (LFQCD) is a complementary approach to the well-established lattice gauge method. LFQCD offers access to the hadrons nonperturbative quark and gluon amplitudes, which are directly testable in experiments at forefront facilities. We present an overview of the promises and challenges of LFQCD in the context of unsolved issues in QCD that require broadened and accelerated investigation. We identify specific goals of this approach and address its quantifiable uncertainties.

Bakker, B. L.G.; Bassetto, A.; Brodsky, S. J.; Broniowski, W.; Dalley, S.; Frederico, T.; Glazek, S. D.; Hiller, J. R.; Ji, C. -R.; Karmanov, V.; Kulshreshtha, D.; Mathiot, J. -F.; Melnitchouk, W.; Miller, G. A.; Papavassiliou, J.; Polyzou, W. N.; Stefanis, N.; Vary, J. P.; Ilderton, A.; Heinzl, T.

2014-06-01T23:59:59.000Z

4

Resonances in coupled pi K, eta K scattering from quantum chromodynamics  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

Using first-principles calculation within Quantum Chromodynamics, we are able to reproduce the pattern of experimental strange resonances which appear as complex singularities within coupled pi K, eta K scattering amplitudes. We make use of numerical computation within the lattice discretized approach to QCD, extracting the energy dependence of scattering amplitudes through their relation- ship to the discrete spectrum of the theory in a finite-volume, which we map out in unprecedented detail.

Dudek, Jozef J [JLAB; Edwards, Robert G [JLAB; Thomas, Christopher E; Wilson, David J

2014-10-01T23:59:59.000Z

5

Quantum Chromodynamics and Nuclear Physics at Extreme Energy Density  

SciTech Connect (OSTI)

The report describes research in theoretical quantum chromodynamics, including effective field theories of hadronic interactions, properties of strongly interacting matter at extreme energy density, phenomenology of relativistic heavy ion collisions, and algorithms and numerical simulations of lattice gauge theory and other many-body systems.

Mueller, B.; Bass, S.A.; Chandrasekharan, S.; Mehen, T.; Springer, R.P.

2005-11-07T23:59:59.000Z

6

Analytic, non-perturbative, gauge-invariant quantum chromodynamics: Nucleon scattering and binding potentials  

SciTech Connect (OSTI)

Removal of the quenched approximation in the mechanism which produced an analytic estimate of quark-binding potentials, along with a reasonable conjecture of the color structure of the nucleon formed by such a binding potential, is shown to generate an effective nucleon scattering and binding potential. The mass-scale factor on the order of the pion mass, previously introduced to define the transverse imprecision of quark coordinates, is again used, while the strength of the potential is proportional to the square of a renormalized quantum chromodynamics (QCD) coupling constant. The potential so derived does not include corrections due to spin, angular momentum, nucleon structure, and electroweak interactions; rather, it is qualitative in nature, showing how Nuclear Physics can arise from fundamental QCD. -- Highlights: •Nucleon–nucleon forces are derived qualitatively from basic realistic quantum chromodynamics. •An effective nucleon binding is obtained from the simplest unquenched approximation. •A model deuteron binding energy of ?2.2 MeV follows with ?{sub s,R}=12.5.

Fried, H.M. [Physics Department, Brown University, Providence, RI 02912 (United States)] [Physics Department, Brown University, Providence, RI 02912 (United States); Gabellini, Y.; Grandou, T. [Université de Nice Sophia-Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS, 06560 Valbonne (France)] [Université de Nice Sophia-Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS, 06560 Valbonne (France); Sheu, Y.-M., E-mail: ymsheu@alumni.brown.edu [Université de Nice Sophia-Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS, 06560 Valbonne (France)

2013-11-15T23:59:59.000Z

7

Two interacting GL-equations in High-T$_c$ superconductivity and quantum chromodynamics  

E-Print Network [OSTI]

The possible connection between High-T$_c$ superconductivity and quantum chromodynamics is considered that is based on two interacting Ginzburg-Landau equations. For High-T$_c$ superconductivity these two equations describe Cooper electrons interacting with different kind of quasi particles (phonons, magnons, excitons and so on). The interaction term describes a possible interaction between different kind of quasi particles. For quantum chromodynamics the equations describe two kinds of gauge condensates. The condensates describe a gauge potential from a subalgebra of the SU(3) gauge group and the corresponding coset. Regular solutions are found which describe the situation where one field, $\\psi_1$, is pushed out by another, $\\psi_2$.

Vladimir Dzhunushaliev

2007-05-22T23:59:59.000Z

8

Magnetic Moments of Light Nuclei from Lattice Quantum Chromodynamics  

E-Print Network [OSTI]

We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton, and [superscript 3]He, along with those of the neutron and proton. These calculations, performed ...

Beane, S.?R.

9

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals  

E-Print Network [OSTI]

A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chira...

Miransky, Vladimir A

2015-01-01T23:59:59.000Z

10

Strongly Correlated Quantum Fluids: Ultracold Quantum Gases, Quantum Chromodynamic Plasmas, and Holographic Duality  

E-Print Network [OSTI]

Strongly correlated quantum fluids are phases of matter that are intrinsically quantum mechanical, and that do not have a simple description in terms of weakly interacting quasi-particles. Two systems that have recently attracted a great deal of interest are the quark-gluon plasma, a plasma of strongly interacting quarks and gluons produced in relativistic heavy ion collisions, and ultracold atomic Fermi gases, very dilute clouds of atomic gases confined in optical or magnetic traps. These systems differ by more than 20 orders of magnitude in temperature, but they were shown to exhibit very similar hydrodynamic flow. In particular, both fluids exhibit a robustly low shear viscosity to entropy density ratio which is characteristic of quantum fluids described by holographic duality, a mapping from strongly correlated quantum field theories to weakly curved higher dimensional classical gravity. This review explores the connection between these fields, and it also serves as an introduction to the Focus Issue of New Journal of Physics on Strongly Correlated Quantum Fluids: from Ultracold Quantum Gases to QCD Plasmas. The presentation is made accessible to the general physics reader and includes discussions of the latest research developments in all three areas.

Allan Adams; Lincoln D. Carr; Thomas Schaefer; Peter Steinberg; John E. Thomas

2012-05-23T23:59:59.000Z

11

Magnetic Moments of Light Nuclei from Lattice Quantum Chromodynamics  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m_pi ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. In particular, we find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures its dominant structure. Similarly a shell-model-like moment is found for the triton, mu_^3H ~ mu_p. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.

Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H W.; Orginos, K.; Parreno, A; Savage, M J.; Tiburzi, B C.

2014-12-01T23:59:59.000Z

12

Model-independent approaches to QCD and B decays  

E-Print Network [OSTI]

We investigate theoretical expectations for B-meson decay rates in the Standard Model. Strong-interaction effects described by quantum chromodynamics (QCD) make this a challenging endeavor. Exact solutions to QCD are not ...

Arnesen, Christian

2007-01-01T23:59:59.000Z

13

Quantum Chromodynamics and nuclear physics at extreme energy density. Progress report, May 1992--April 1993  

SciTech Connect (OSTI)

This report discusses research in the following topics: Hadron structure physics; relativistic heavy ion collisions; finite- temperature QCD; real-time lattice gauge theory; and studies in quantum field theory.

Mueller, B.

1993-05-15T23:59:59.000Z

14

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals  

E-Print Network [OSTI]

A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...

Vladimir A. Miransky; Igor A. Shovkovy

2015-04-10T23:59:59.000Z

15

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals  

E-Print Network [OSTI]

A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...

Vladimir A. Miransky; Igor A. Shovkovy

2015-03-02T23:59:59.000Z

16

Maximal Wavelength of Confined Quarks and Gluons and Properties of Quantum Chromodynamics  

SciTech Connect (OSTI)

Because quarks and gluons are confined within hadrons, they have a maximum wavelength of order the confinement scale. Propagators, normally calculated for free quarks and gluons using Dyson-Schwinger equations, are modified by bound-state effects in close analogy to the calculation of the Lamb shift in atomic physics. Because of confinement, the effective quantum chromodynamic coupling stays finite in the infrared. The quark condensate which arises from spontaneous chiral symmetry breaking in the bound state Dyson-Schwinger equation is the expectation value of the operator {bar q}q evaluated in the background of the fields of the other hadronic constituents, in contrast to a true vacuum expectation value. Thus quark and gluon condensates reside within hadrons. The effects of instantons are also modified. We discuss the implications of the maximum quark and gluon wavelength for phenomena such as deep inelastic scattering and annihilation, the decay of heavy quarkonia, jets, and dimensional counting rules for exclusive reactions. We also discuss implications for the zero-temperature phase structure of a vectorial SU(N) gauge theory with a variable number N{sub f} of massless fermions.

Brodsky, Stanley J.; /SLAC /YITP, Stony Brook /Durham U.; Shrock, Robert; /YITP, Stony Brook

2008-08-01T23:59:59.000Z

17

Hadronic Resonances from Lattice QCD  

SciTech Connect (OSTI)

The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

John Bulava; Robert Edwards; George Fleming; K. Jimmy Juge; Adam C. Lichtl; Nilmani Mathur; Colin Morningstar; David Richards; Stephen J. Wallace

2007-06-16T23:59:59.000Z

18

Hadronic Resonances from Lattice QCD  

SciTech Connect (OSTI)

The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

Lichtl, Adam C. [RBRC, Brookhaven National Laboratory, Upton, NY 11973 (United States); Bulava, John; Morningstar, Colin [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Edwards, Robert; Mathur, Nilmani; Richards, David [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Fleming, George [Yale University, New Haven, CT 06520 (United States); Juge, K. Jimmy [Department of Physics, University of the Pacific, Stockton, CA 95211 (United States); Wallace, Stephen J. [University of Maryland, College Park, MD 20742 (United States)

2007-10-26T23:59:59.000Z

19

Hyperon-Nucleon Interactions and the Composition of Dense Nuclear Matter from Quantum Chromodynamics  

E-Print Network [OSTI]

The low-energy neutron-Sigma^- interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from a numerical evaluation of the QCD path integral using the technique of Lattice QCD. Our calculations, performed at a pion mass of m_pi ~ 389 MeV in two large lattice volumes, and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The interactions determined from QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties, and strengthen theoretical arguments that the strange quark is a crucial component of dense nuclear matter.

S. R. Beane; E. Chang; S. D. Cohen; W. Detmold; H. -W. Lin; T. C. Luu; K. Orginos; A. Parreno; M. J. Savage; A. Walker-Loud

2012-04-16T23:59:59.000Z

20

Challenges to quantum chromodynamics: Anomalous spin, heavy quark, and nuclear phenomena  

SciTech Connect (OSTI)

The general structure of QCD meshes remarkably well with the facts of the hadronic world, especially quark-based spectroscopy, current algebra, the approximate point-like structure of large momentum transfer inclusive reactions, and the logarithmic violation of scale invariance in deep inelastic lepton-hadron reactions. QCD has been successful in predicting the features of electron-positron and photon-photon annihilation into hadrons, including the magnitude and scaling of the cross sections, the shape of the photon structure function, the production of hadronic jets with patterns conforming to elementary quark and gluon subprocesses. The experimental measurements appear to be consistent with basic postulates of QCD, that the charge and weak currents within hadrons are carried by fractionally-charged quarks, and that the strength of the interactions between the quarks, and gluons becomes weak at short distances, consistent with asymptotic freedom. Nevertheless in some cases, the predictions of QCD appear to be in dramatic conflict with experiment. The anomalies suggest that the proton itself as a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrival proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trival oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non- negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. 144 refs., 46 figs., 2 tabs.

Brodsky, S.J.

1989-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Energy spectra and wave function of trigonometric Rosen-Morse potential as an effective quantum chromodynamics potential in D-dimensions  

SciTech Connect (OSTI)

The Energy Spectra and Wave Function of Schrodinger equation in D-Dimensions for trigonometric Rosen-Morse potential were investigated analytically using Nikiforov-Uvarov method. This potential captures the essential traits of the quark-gluon dynamics of Quantum Chromodynamics. The approximate energy spectra are given in the close form and the corresponding approximate wave function for arbitrary l-state (l ? 0) in D-dimensions are formulated in the form of differential polynomials. The wave function of this potential unnormalizable for general case. The wave function of this potential unnormalizable for general case. The existence of extra dimensions (centrifugal factor) and this potential increase the energy spectra of system.

Deta, U. A., E-mail: utamaalan@yahoo.co.id [Theoretical Physics Group, Physics Department of Post Graduate Program, Sebelas Maret University, Jl. Ir. Sutami 36A, Surakarta 57126, Indonesia and Physics Department, State University of Surabaya, Jl. Ketintang, Surabaya 60231 (Indonesia); Suparmi,; Cari,; Husein, A. S.; Yuliani, H.; Khaled, I. K. A.; Luqman, H.; Supriyanto [Theoretical Physics Group, Physics Department of Post Graduate Program, Sebelas Maret University, Jl. Ir. Sutami 36A, Surakarta 57126 (Indonesia)

2014-09-30T23:59:59.000Z

22

The Symmetries of QCD  

ScienceCinema (OSTI)

The symmetries of a quantum field theory can be realized in a variety of ways. Symmetries can be realized explicitly, approximately, through spontaneous symmetry breaking or, via an anomaly, quantum effects can dynamically eliminate a symmetry of the theory that was present at the classical level.  Quantum Chromodynamics (QCD), the modern theory of the strong interactions, exemplify each of these possibilities. The interplay of these effects determine the spectrum of particles that we observe and, ultimately, account for 99% of the mass of ordinary matter. 

Sekhar Chivukula

2010-01-08T23:59:59.000Z

23

Kenneth Wilson and lattice QCD  

E-Print Network [OSTI]

We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward b...

Ukawa, Akira

2015-01-01T23:59:59.000Z

24

Kenneth Wilson and lattice QCD  

E-Print Network [OSTI]

We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward better understanding of physics, better algorithms, and more powerful supercomputers have produced major breakthroughs in our understanding of the strong interactions. We review the salient results of this effort in understanding the hadron spectrum, the Cabibbo-Kobayashi-Maskawa matrix elements and CP violation, and quark-gluon plasma at high temperatures. We conclude with a brief summary and a future perspective.

Akira Ukawa

2015-01-21T23:59:59.000Z

25

Sudakov Safety in Perturbative QCD  

E-Print Network [OSTI]

Traditional calculations in perturbative quantum chromodynamics (pQCD) are based on an order-by-order expansion in the strong coupling $\\alpha_s$. Observables that are calculable in this way are known as "safe". Recently, a class of unsafe observables was discovered that do not have a valid $\\alpha_s$ expansion but are nevertheless calculable in pQCD using all-orders resummation. These observables are called "Sudakov safe" since singularities at each $\\alpha_s$ order are regulated by an all-orders Sudakov form factor. In this letter, we give a concrete definition of Sudakov safety based on conditional probability distributions, and we study a one-parameter family of momentum sharing observables that interpolate between the safe and unsafe regimes. The boundary between these regimes is particularly interesting, as the resulting distribution can be understood as the ultraviolet fixed point of a generalized fragmentation function, yielding a leading behavior that is independent of $\\alpha_s$.

Larkoski, Andrew J; Thaler, Jesse

2015-01-01T23:59:59.000Z

26

Sudakov Safety in Perturbative QCD  

E-Print Network [OSTI]

Traditional calculations in perturbative quantum chromodynamics (pQCD) are based on an order-by-order expansion in the strong coupling $\\alpha_s$. Observables that are calculable in this way are known as "safe". Recently, a class of unsafe observables was discovered that do not have a valid $\\alpha_s$ expansion but are nevertheless calculable in pQCD using all-orders resummation. These observables are called "Sudakov safe" since singularities at each $\\alpha_s$ order are regulated by an all-orders Sudakov form factor. In this letter, we give a concrete definition of Sudakov safety based on conditional probability distributions, and we study a one-parameter family of momentum sharing observables that interpolate between the safe and unsafe regimes. The boundary between these regimes is particularly interesting, as the resulting distribution can be understood as the ultraviolet fixed point of a generalized fragmentation function, yielding a leading behavior that is independent of $\\alpha_s$.

Andrew J. Larkoski; Simone Marzani; Jesse Thaler

2015-02-05T23:59:59.000Z

27

QCD Critical Point: The Race is On  

E-Print Network [OSTI]

A critical point in the phase diagram of Quantum Chromodynamics (QCD), if established either theoretically or experimentally, would be as profound a discovery as the good-old gas-liquid critical point. Unlike the latter, however, first-principles based approaches are being employed to locate it theoretically. Due to the short lived nature of the concerned phases, novel experimental techniques are needed to search for it. The Relativistic Heavy Ion Collider (RHIC) in USA has an experimental program to do so. This short review is an attempt to provide a glimpse of the race between the theorists and the experimentalists as well as that of the synergy between them.

Rajiv V. Gavai

2014-04-26T23:59:59.000Z

28

Nuclear Reactions from Lattice QCD  

E-Print Network [OSTI]

One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low- energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.

Raúl A. Briceño; Zohreh Davoudi; Thomas C. Luu

2014-11-25T23:59:59.000Z

29

Nuclear reactions from lattice QCD  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low- energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.

Briceno, Raul A. [JLAB; Davoudi, Zohreh; Luu, Thomas C.

2015-02-01T23:59:59.000Z

30

CT10 NLO and NNLO Parton Distribution Functions from the Coordinated Theoretical-Experimental Project on QCD  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

The Coordinated Theoretical-Experimental Project on QCD is a multi-institutional collaboration devoted to a broad program of research projects and cooperative enterprises in high-energy physics centered on Quantum Chromodynamics (QCD) and its implications in all areas of the Standard Model and beyond. The Collaboration consists of theorists and experimentalists at 18 universities and 5 national laboratories. More than 65 sets of Parton Distribution Functions are available for public access. Links to many online software tools, information about Parton Distribution Functions, papers, and other resources are also available.

Huston, Joey (Co-Spokesperson); Ownes, Joseph (Co-Spokesperson)

31

Precise QCD predictions for the production of Higgs+jet final states  

E-Print Network [OSTI]

We compute the cross section and differential distributions for the production of a Standard Model Higgs boson in association with a hadronic jet to next-to-next-to-leading order in quantum chromodynamics (QCD). In Higgs boson studies at the LHC, final states containing one jet are a dominant contribution to the total event rate, and their understanding is crucial for improved determinations of the Higgs boson properties. We observe substantial higher order corrections to transverse momentum spectra and rapidity distributions in Higgs-plus-one-jet final states. Their inclusion stabilises the residual theoretical uncertainty of the predictions around 9\\%, thereby providing important input to precision studies of the Higgs boson.

X. Chen; T. Gehrmann; E. W. N. Glover; M. Jaquier

2014-08-22T23:59:59.000Z

32

Exclusive Processes: Tests of Coherent QCD Phenomena and Nucleon Substructure at CEBAF -  

E-Print Network [OSTI]

Measurements of exclusive processes such as electroproduction, photoproduction, and Compton scattering are among the most sensitive probes of proton structure and coherent phenomena in quantum chromodynamics. The continuous electron beam at CEBAF, upgraded in laboratory energy to 10--12 GeV, will allow a systematic study of exclusive, semi-inclusive, and inclusive reactions in a kinematic range well-tuned to the study of fundamental nucleon and nuclear substructure. I also discuss the potential at CEBAF for studying novel QCD phenomena at the charm production threshold, including the possible production of nuclear-bound quarkonium.

Stanley J. Brodsky; SLAC

1994-07-22T23:59:59.000Z

33

QCD, Tevatron results and LHC prospects  

SciTech Connect (OSTI)

We present a summary of the most recent measurements relevant to Quantum Chromodynamics (QCD) delivered by the D0 and CDF Tevatron experiments by May 2008. CDF and D0 are moving toward precision measurements of QCD based on data samples in excess of 1 fb-1. The inclusive jet cross sections have been extended to forward rapidity regions and measured with unprecedented precision following improvements in the jet energy calibration. Results on dijet mass distributions, bbbar dijet production using tracker based triggers, underlying event in dijet and Drell-Yan samples, inclusive photon and diphoton cross sections complete the list of measurements included in this paper. Good agreement with pQCD within errors is observed for jet production measurements. An improved and consistent theoretical description is needed for photon+jets processes. Collisions at the LHC are scheduled for early fall 2008, opening an era of discoveries at the new energy frontier, 5-7 times higher than that of the Tevatron.

Elvira, V.Daniel; /Fermilab

2008-08-01T23:59:59.000Z

34

Lattice QCD Thermodynamics on the Grid  

E-Print Network [OSTI]

We describe how we have used simultaneously ${\\cal O}(10^3)$ nodes of the EGEE Grid, accumulating ca. 300 CPU-years in 2-3 months, to determine an important property of Quantum Chromodynamics. We explain how Grid resources were exploited efficiently and with ease, using user-level overlay based on Ganga and DIANE tools above standard Grid software stack. Application-specific scheduling and resource selection based on simple but powerful heuristics allowed to improve efficiency of the processing to obtain desired scientific results by a specified deadline. This is also a demonstration of combined use of supercomputers, to calculate the initial state of the QCD system, and Grids, to perform the subsequent massively distributed simulations. The QCD simulation was performed on a $16^3\\times 4$ lattice. Keeping the strange quark mass at its physical value, we reduced the masses of the up and down quarks until, under an increase of temperature, the system underwent a second-order phase transition to a quark-gluon plasma. Then we measured the response of this system to an increase in the quark density. We find that the transition is smoothened rather than sharpened. If confirmed on a finer lattice, this finding makes it unlikely for ongoing experimental searches to find a QCD critical point at small chemical potential.

Jakub T. Mo?cicki; Maciej Wo?; Massimo Lamanna; Philippe de Forcrand; Owe Philipsen

2009-11-30T23:59:59.000Z

35

Deflation for inversion with multiple right-hand sides in QCD  

SciTech Connect (OSTI)

Most calculations in lattice Quantum Chromodynamics (QCD) involve the solution of a series of linear systems of equations with exceedingly large matrices and a large number of right hand sides. Iterative methods for these problems can be sped up significantly if we deflate approximations of appropriate invariant spaces from the initial guesses. Recently we have developed eigCG, a modification of the Conjugate Gradient (CG) method, which while solving a linear system can reuse a window of the CG vectors to compute eigenvectors almost as accurately as the Lanczos method. The number of approximate eigenvectors can increase as more systems are solved. In this paper we review some of the characteristics of eigCG and show how it helps remove the critical slowdown in QCD calculations. Moreover, we study scaling with lattice volume and an extension of the technique to nonsymmetric problems.

A. Stathopoulos, A.M. Abdel-Rehim, K. Orginos,

2009-06-01T23:59:59.000Z

36

Off-shell photon distribution amplitudes in the low-energy effective theory of QCD  

E-Print Network [OSTI]

Based on the principle of the Lorentz covariance the transition matrix elements from an off-shell photon state to the vacuum are decomposed into the light-cone photon DAs, in which only two transversal DAs survive in the on-shell limit. The eight off-shell light-cone photon distribution amplitudes (DAs) corresponding to chiral-odd and chiral-even up to twist-four and the corresponding coupling constants are studied systematically in the instanton vacuum model of quantum chromodynamics (QCD). The various individual photon DA multiplied by its corresponding coupling constant is expressed in terms of the correlation functions, which are connected with the spectral densities of an effective quark propagator, and then evaluated in the low-energy effective theory derived from the instanton vacuum model of QCD. The explicit analytical expressions and the numerical results for the photon DAs and their coupling constants are given.

Xin Mo; Jueping Liu

2014-02-25T23:59:59.000Z

37

Hadron Physics and QCD: Just the Basic Facts  

E-Print Network [OSTI]

With discovery of the Higgs boson, the Standard Model of Particle Physics became complete. Its formulation is a remarkable story; and the process of verification is continuing, with the most important chapter being the least well understood. Quantum Chromodynamics (QCD) is that part of the Standard Model which is supposed to describe all of nuclear physics and yet, almost fifty years after the discovery of quarks, we are only just beginning to understand how QCD moulds the basic bricks for nuclei: pious, neutrons, protons. QCD is characterized by two emergent phenomena: confinement and dynamical chiral symmetry breaking (DCSB), whose implications are extraordinary. This contribution describes how DCSB, not the Higgs boson, generates more than 98% of the visible mass in the Universe, explains why confinement guarantees that condensates, those quantities that were commonly viewed as constant mass-scales that fill all spacetime, are instead wholly contained within hadrons, and elucidates a range of observable consequences of confinement and DCSB whose measurement is the focus of a vast international experimental programme.

Craig D. Roberts

2015-01-26T23:59:59.000Z

38

DSE Perspective on QCD Modeling, Distribution Amplitudes, and Form Factors  

E-Print Network [OSTI]

We describe results for the pion distribution amplitude (PDA) at the non-perturbative scale $\\mu=~$2GeV by projecting the Poincar\\'e-covariant Bethe-Salpeter wave-function onto the light-front and use it to investigate the ultraviolet behavior of the electromagnetic form factor, $F_\\pi(Q^2)$, on the entire domain of spacelike $Q^2$. The significant dilation of this PDA compared to the known asymptotic PDA is a signature of dynamical chiral symmetry breaking (DCSB) on the light front. We investigate the transition region of $Q^2$ where non-perturbative behavior of constituent-like quarks gives way to the partonic-like behavior of quantum chromodynamics (QCD). The non-perturbative approach is based on the Dyson-Schwinger equation (DSE) framework for continuum investigations in QCD. The leading-order, leading-twist perturbative QCD result for $Q^2 F_\\pi(Q^2)$ underestimates the new DSE computation by just 15\\% on $Q^2\\gtrsim 8\\,$GeV$^2$, in stark contrast with the result obtained using the asymptotic PDA.

Peter C Tandy

2014-07-02T23:59:59.000Z

39

Real-Time thermal Ward-Takahashi Identity for vectorial current in QED and QCD  

E-Print Network [OSTI]

It is shown that, by means of canonical operator approach, the Ward-Takahashi identity (WTI) at finite temperature $T$ and finite chemical potential $\\mu$ for complete vectorial vertex and complete fermion propagator can be simply proven, rigorously for Quantum Electrodynamics (QED) and approximately for Quantum Chromodynamics (QCD) where the ghost effect in the fermion sector is neglected. The WTI shown in the real-time thermal matrix form will give definite thermal constraints on the imaginary part of inverse complete Feynman propagator including self-energy for fermion and will play important role in relevant physical processes. When the above inverse propagator is assumed to be real, the thermal WTI will essentially be reduced to its form at $T=\\mu=0$ thus one can use it in the latter's form. At this point, a practical example is indicated.

Zhou Bang-Rong

2005-12-05T23:59:59.000Z

40

Formal Developments for Lattice QCD with Applications to Hadronic Systems  

E-Print Network [OSTI]

Lattice quantum chromodynamics (QCD) will soon become the primary theoretical tool in rigorous studies of single- and multi-hadron sectors of QCD. It is truly ab initio meaning that its only parameters are those of standard model. The result of a lattice QCD calculation corresponds to that of nature only in the limit when the volume of spacetime is taken to infinity and the spacing between discretized points on the lattice is taken to zero. A better understanding of these discretization and volume effects not only provides the connection to the infinite-volume continuum observables, but also leads to optimized calculations that can be performed with available computational resources. This thesis includes various formal developments in this direction, along with proposals for improvements, to be applied to the upcoming lattice QCD studies of nuclear and hadronic systems. Among these developments are i) an analytical investigation of the recovery of rotational symmetry with the use of suitably-formed smeared operators toward the continuum limit, ii) an extension of the Luscher finite-volume method to two-nucleon systems with arbitrary angular momentum, spin, parity and center of mass momentum, iii) the application of such formalism in extracting the scattering parameters of the 3S1-3D1 coupled channels, iv) an investigation of twisted boundary conditions in the single- and two-hadron sectors, with proposals for improving the volume-dependence of the deuteron binding energy upon proper choices of boundary conditions, and v) exploring the volume dependence of the masses of hadrons and light-nuclei due to quantum electrodynamic interactions, including the effects arising from particles' compositeness. The required background as well as a brief status report of the field pertinent to the discussions in this thesis are presented.

Zohreh Davoudi

2014-09-05T23:59:59.000Z

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41

Transversity from First Principles in QCD  

SciTech Connect (OSTI)

Transversity observables, such as the T-odd Sivers single-spin asymmetry measured in deep inelastic lepton scattering on polarized protons and the distributions which are measured in deeply virtual Compton scattering, provide important constraints on the fundamental quark and gluon structure of the proton. In this talk I discuss the challenge of computing these observables from first principles; i.e.; quantum chromodynamics, itself. A key step is the determination of the frame-independent light-front wavefunctions (LFWFs) of hadrons - the QCD eigensolutions which are analogs of the Schroedinger wavefunctions of atomic physics. The lensing effects of initial-state and final-state interactions, acting on LFWFs with different orbital angular momentum, lead to T-odd transversity observables such as the Sivers, Collins, and Boer-Mulders distributions. The lensing effect also leads to leading-twist phenomena which break leading-twist factorization such as the breakdown of the Lam-Tung relation in Drell-Yan reactions. A similar rescattering mechanism also leads to diffractive deep inelastic scattering, as well as nuclear shadowing and non-universal antishadowing. It is thus important to distinguish 'static' structure functions, the probability distributions computed the target hadron's light-front wavefunctions, versus 'dynamical' structure functions which include the effects of initial- and final-state rescattering. I also discuss related effects such as the J = 0 fixed pole contribution which appears in the real part of the virtual Compton amplitude. AdS/QCD, together with 'Light-Front Holography', provides a simple Lorentz-invariant color-confining approximation to QCD which is successful in accounting for light-quark meson and baryon spectroscopy as well as hadronic LFWFs.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

2012-02-16T23:59:59.000Z

42

Hybrid meson decay from lattice QCD  

E-Print Network [OSTI]

Besides the conventional hadrons containing valence quarks and valence antiquarks, quantum chromodynamics (QCD) suggests the existence of the hybrid hadrons containing valence gluons in addition to the quarks and antiquarks, and some experiments may have found some. A decisive experimental confirmation of its existence, however, is still needed. At present, lattice simulations have offered the practicable ways of theoretically guiding us to search for the hybrid states. In this dissertation, we study the spectroscopy and the decay rate of the heavy hybrid mesons made of a heavy $b$ quark, a heavy $\\bar b$ antiquark, and a gluon ($b\\bar{b}g$) to selected channels, and use lattice methods to extract the transition matrix elements in full QCD. We are particular interested in the spin-exotic hybrid mesons. For sufficiently heavy quarks (e.g., $b$ quark), we use the leading Born-Oppenheimer (LBO) approximation to calculate the static potential energy at all $b\\bar{b}$ separations. Then, by solving the Schr\\"odinger equation with this potential, we reconstruct the motion of the heavy quarks. In a similar way we can determine decay rates. In this dissertation, we use the numerical lattice method to calculate the mass of the $f_0$ meson at a single lattice spacing and light quark mass, namely, $m_{f_0} = (768 \\pm 136)$ MeV. Most of all we consider the decay channels involving the production of a scalar meson. We obtain the partial decay rate ($\\Gamma$) for the channel $ H \\rightarrow \\chi_b + \\pi + \\pi $, namely, $ \\Gamma = 3.62(98)$ MeV. All of our results are consistent with those of other researchers. Knowledge of the masses and the decay rates should help us considerably in experimental searches for the hybrid mesons.

Ziwen Fu

2011-03-08T23:59:59.000Z

43

Light-Front Holographic QCD  

SciTech Connect (OSTI)

The relation between the hadronic short-distance constituent quark and gluon particle limit and the long-range confining domain is yet one of the most challenging aspects of particle physics due to the strong coupling nature of Quantum Chromodynamics, the fundamental theory of the strong interactions. The central question is how one can compute hadronic properties from first principles; i.e., directly from the QCD Lagrangian. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time. Lattice numerical results follow from computation of frame-dependent moments of distributions in Euclidean space and dynamical observables in Minkowski spacetime, such as the time-like hadronic form factors, are not amenable to Euclidean lattice computations. The Dyson-Schwinger methods have led to many important insights, such as the infrared fixed point behavior of the strong coupling constant, but in practice, the analyses are limited to ladder approximation in Landau gauge. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. New theoretical tools are thus of primary interest for the interpretation of the results expected at the new mass scale and kinematic regions accessible to the JLab 12 GeV Upgrade Project. The AdS/CFT correspondence between gravity or string theory on a higher-dimensional anti-de Sitter (AdS) space and conformal field theories in physical space-time has led to a semiclassical approximation for strongly-coupled QCD, which provides physical insights into its nonperturbative dynamics. The correspondence is holographic in the sense that it determines a duality between theories in different number of space-time dimensions. This geometric approach leads in fact to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian 'Light-Front Holography'. Light-Front Holography is in fact one of the most remarkable features of the AdS/CFT correspondence. The Hamiltonian equation of motion in the light-front (LF) is frame independent and has a structure similar to eigenmode equations in AdS space. This makes a direct connection of QCD with AdS/CFT methods possible. Remarkably, the AdS equations correspond to the kinetic energy terms of the partons inside a hadron, whereas the interaction terms build confinement and correspond to the truncation of AdS space in an effective dual gravity approximation. One can also study the gauge/gravity duality starting from the bound-state structure of hadrons in QCD quantized in the light-front. The LF Lorentz-invariant Hamiltonian equation for the relativistic bound-state system is P{sub {mu}}P{sup {mu}}|{psi}(P)> = (P{sup +}P{sup -} - P{sub {perpendicular}}{sup 2})|{psi}(P)> = M{sup 2}|{psi}(P)>, P{sup {+-}} = P{sup 0} {+-} P{sup 3}, where the LF time evolution operator P{sup -} is determined canonically from the QCD Lagrangian. To a first semiclassical approximation, where quantum loops and quark masses are not included, this leads to a LF Hamiltonian equation which describes the bound-state dynamics of light hadrons in terms of an invariant impact variable {zeta} which measures the separation of the partons within the hadron at equal light-front time {tau} = x{sup 0} + x{sup 3}. This allows us to identify the holographic variable z in AdS space with an impact variable {zeta}. The resulting Lorentz-invariant Schroedinger equation for general spin incorporates color confinement and is systematically improvable. Light-front holographic methods were originally introduced by matching the electromagnetic current matrix elements in AdS space with the corresponding expression using LF theory in physical space time. It was also shown that one obtains identical holographic mapping using the matrix elements of the energy-momentum tensor by perturbing the AdS metric around its static solution. A gravity dual to QCD is not known, but th

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.

2012-02-16T23:59:59.000Z

44

Nuclear Forces from Lattice Quantum Chromodynamics Martin J. Savage  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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45

ANL/ALCF/ESP-13/11 Lattice Quantum Chromodynamics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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46

Lattice Quantum Chromodynamics Project and SCience Gateway at NERSC  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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47

Flavor independence and the dual superconducting model of QCD  

SciTech Connect (OSTI)

Baker, Ball, and Zachariasen (BBZ) have developed an elegant formulation of the dual superconducting model of quantum chromodynamics (QCD), which allows one to use the field equations to eliminate the gluon and Higgs degrees of freedom and thus to express the interaction between quarks as an effective potential. Carrying out an expansion in inverse powers of the constituent quark masses, these authors succeeded in identifying the central part, the spin-dependent part, and the leading relativistic corrections to the central potential. The potential offers a good account of the energies and splittings of charmonium and the upsilon system. Since all of the flavor dependence of the interaction is presumed to enter through the constituent masses, it is possible to test the potential in other systems. Logical candidates are the heavy B-flavor charmed system and the heavy-light systems, which should be more sensitive to the relativistic corrections. Lattice gauge calculations furnish an additional point of contact for the components of the BBZ potential. Some preliminary calculations of the energies of B and D mesons are presented and the challenge of agreement with experiment is discussed. The spinless Salpeter equation is used to account for the effects of relativistic kinematics. {copyright} {ital 1997} {ital The American Physical Society}

Fulcher, L.P. [Department of Physics and Astronomy, Bowling Green State University, Bowling Green, Ohio 43403 (United States)] [Department of Physics and Astronomy, Bowling Green State University, Bowling Green, Ohio 43403 (United States)

1998-01-01T23:59:59.000Z

48

Silver Blaze Puzzle in 1/Nc Expansions of Cold and Dense QCD Matter  

E-Print Network [OSTI]

We consider quantum chromodynamics (QCD) with Nc colors and Nf quark flavors at finite quark chemical potential mu_q or isospin chemical potential mu_I. We specifically address the nature of the ``Silver Blaze'' behavior in the framework of 1/Nc expansion. Starting with the QCD partition function, we implement Veneziano's Nf/Nc expansion to identify the density onset. We find the baryon mass M_B and the pion mass m_pi appearing from different order of Veneziano's expansion. We argue that the confining properties are responsible for the Silver Blaze in the region of m_pi/2 < mu_q < M_B/Nc. We point out, however, that Veneziano's expansion brings about a puzzling subtlety along the same line as the baryon problem in finite-density quenched simulations. We emphasize that the large-Nc limit can allow for the physical ordering of M_B and m_pi thanks to the similarity to the quenched approximation, while the unphysical ghost quarks contaminate the baryon sector if Nc is finite. We also discuss the ``orientifold'' large-Nc limit that does not quench quark loops.

Adi Armoni; Kenji Fukushima

2014-03-10T23:59:59.000Z

49

Lattice QCD  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Lattice QCD Lattice QCD Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505) 667-5657 Email...

50

The QCD/SM working group: Summary report  

SciTech Connect (OSTI)

Quantum Chromo-Dynamics (QCD), and more generally the physics of the Standard Model (SM), enter in many ways in high energy processes at TeV Colliders, and especially in hadron colliders (the Tevatron at Fermilab and the forthcoming LHC at CERN), First of all, at hadron colliders, QCD controls the parton luminosity, which rules the production rates of any particle or system with large invariant mass and/or large transverse momentum. Accurate predictions for any signal of possible ''New Physics'' sought at hadron colliders, as well as the corresponding backgrounds, require an improvement in the control of uncertainties on the determination of PDF and of the propagation of these uncertainties in the predictions. Furthermore, to fully exploit these new types of PDF with uncertainties, uniform tools (computer interfaces, standardization of the PDF evolution codes used by the various groups fitting PDF's) need to be proposed and developed. The dynamics of colour also affects, both in normalization and shape, various observables of the signals of any possible ''New Physics'' sought at the TeV scale, such as, e.g. the production rate, or the distributions in transverse momentum of the Higgs boson. Last, but not least, QCD governs many backgrounds to the searches for this ''New Physics''. Large and important QCD corrections may come from extra hard parton emission (and the corresponding virtual corrections), involving multi-leg and/or multi-loop amplitudes. This requires complex higher order calculations, and new methods have to be designed to compute the required multi-legs and/or multi-loop corrections in a tractable form. In the case of semi-inclusive observables, logarithmically enhanced contributions coming from multiple soft and collinear gluon emission require sophisticated QCD resummation techniques. Resummation is a catch-all name for efforts to extend the predictive power of QCD by summing the large logarithmic corrections to all orders in perturbation theory. In practice, the resummation formalism depends on the observable at issue, through the type of logarithm to be resummed, and the resummation methods. In parallel with this perturbative QCD-oriented working programme, the implementation of both QCD/SM and New physics in Monte Carlo event generators is confronted with a number of issues which deserve uniformization or improvements. The important issues are: (1) the problem of interfacing partonic event generators to showering Monte-Carlos; (2) an implementation using this interface to calculate backgrounds which are poorly simulated by the showering Monte-Carlos alone; (3) a comparison of the HERWIG and PYTHIA parton shower models with the predictions of soft gluon resummation; (4) studies of the underlying events at hadron colliders to check how well they are modeled by the Monte-Carlo generators.

W. Giele et al.

2004-01-12T23:59:59.000Z

51

A Matrix Model for QCD: QCD Colour is Mixed  

E-Print Network [OSTI]

We use general arguments to show that coloured QCD states when restricted to gauge invariant local observables are mixed. This result has important implications for confinement: a pure colourless state can never evolve into two coloured states by unitary evolution. Furthermore, the mean energy in such a mixed coloured state is infinite. Our arguments are confirmed in a matrix model for QCD that we have developed using the work of Narasimhan and Ramadas and Singer. This model, a $(0+1)$-dimensional quantum mechanical model for gluons free of divergences and capturing important topological aspects of QCD, is adapted to analytical and numerical work. It is also suitable to work on large $N$ QCD. As applications, we show that the gluon spectrum is gapped and also estimate some low-lying levels for $N=2$ and 3 (colors). Incidentally the considerations here are generic and apply to any non-abelian gauge theory.

A. P. Balachandran; Amilcar de Queiroz; Sachindeo Vaidya

2014-08-13T23:59:59.000Z

52

Quantum and stringy corrections to the equation of state of holographic QCD matter and the nature of the chiral transition  

E-Print Network [OSTI]

We consider the finite temperature phase diagram of holographic QCD in the Veneziano limit (Nc large, Nf large with xf=Nf/Nc fixed) and calculate one string-loop corrections to the free energy in certain approximations. Such corrections, especially due to the pion modes are unsuppressed in the Veneziano limit. We find that under some extra assumptions the first order transition following from classical gravity solutions can become second order. If stringy asymptotics are of a special form and there are residual interactions it may even become of third order. Operationally these computations imply modelling the low temperature chiral symmetry breaking phase with a hadron gas containing Nf^2 massless Goldstone bosons and an exponential spectrum of massive hadrons. A third order transition is possible only if repulsive hadron interactions via the excluded volume effect are included.

T. Alho; M. Jarvinen; K. Kajantie; E. Kiritsis; K. Tuominen

2015-03-26T23:59:59.000Z

53

Quantum and stringy corrections to the equation of state of holographic QCD matter and the nature of the chiral transition  

E-Print Network [OSTI]

We consider the finite temperature phase diagram of holographic QCD in the Veneziano limit (Nc large, Nf large with xf=Nf/Nc fixed) and calculate one string-loop corrections to the free energy in certain approximations. Such corrections, especially due to the pion modes are unsuppressed in the Veneziano limit. We find that under some extra assumptions the first order transition following from classical gravity solutions can become second order. If stringy asymptotics are of a special form and there are residual interactions it may even become of third order. Operationally these computations imply modelling the low temperature chiral symmetry breaking phase with a hadron gas containing Nf^2 massless Goldstone bosons and an exponential spectrum of massive hadrons. A third order transition is possible only if repulsive hadron interactions via the excluded volume effect are included.

Alho, T; Kajantie, K; Kiritsis, E; Tuominen, K

2015-01-01T23:59:59.000Z

54

Proceedings of RIKEN BNL Research Center Workshop entitled Hydrodynamics in Heavy Ion Collisions and QCD Equation of State (Volume 88)  

SciTech Connect (OSTI)

The interpretation of relativistic heavy-ion collisions at RHIC energies with thermal concepts is largely based on the relative success of ideal (nondissipative) hydrodynamics. This approach can describe basic observables at RHIC, such as particle spectra and momentum anisotropies, fairly well. On the other hand, recent theoretical efforts indicate that dissipation can play a significant role. Ideally viscous hydrodynamic simulations would extract, if not only the equation of state, but also transport coefficients from RHIC data. There has been a lot of progress with solving relativistic viscous hydrodynamics. There are already large uncertainties in ideal hydrodynamics calculations, e.g., uncertainties associated with initial conditions, freezeout, and the simplified equations of state typically utilized. One of the most sensitive observables to the equation of state is the baryon momentum anisotropy, which is also affected by freezeout assumptions. Up-to-date results from lattice quantum chromodynamics on the transition temperature and equation of state with realistic quark masses are currently available. However, these have not yet been incorporated into the hydrodynamic calculations. Therefore, the RBRC workshop 'Hydrodynamics in Heavy Ion Collisions and QCD Equation of State' aimed at getting a better understanding of the theoretical frameworks for dissipation and near-equilibrium dynamics in heavy-ion collisions. The topics discussed during the workshop included techniques to solve the dynamical equations and examine the role of initial conditions and decoupling, as well as the role of the equation of state and transport coefficients in current simulations.

Karsch,F.; Kharzeev, D.; Molnar, K.; Petreczky, P.; Teaney, D.

2008-04-21T23:59:59.000Z

55

A Matrix Model for QCD  

E-Print Network [OSTI]

Gribov's observation that global gauge fixing is impossible has led to suggestions that there may be a deep connection between gauge-fixing and confinement. We find an unexpected relation between the topological non-triviality of the gauge bundle and coloured states in $SU(N)$ Yang-Mills theory, and show that such states are necessarily impure. We approximate QCD by a rectangular matrix model that captures the essential topological features of the gauge bundle, and demonstrate the impure nature of coloured states explicitly. Our matrix model also allows the inclusion of the QCD $\\theta$-term, as well as to perform explicit computations of low-lying glueball masses. This mass spectrum is gapped. Since an impure state cannot evolve to a pure one by a unitary transformation, our result shows that the solution to the confinement problem in pure QCD is fundamentally quantum information-theoretic.

Balachandran, A P; de Queiroz, Amilcar R

2014-01-01T23:59:59.000Z

56

QCD Thermodynamics  

E-Print Network [OSTI]

Recent results on QCD thermodynamics are presented. The nature of the T>0 transition is determined, which turns out to be an analytic cross-over. The absolute scale for this transition is calculated. The temperature dependent static potential is given. The results were obtained by using a Symanzik improved gauge and stout-link improved fermionic action. In order to approach the continuum limit four different sets of lattice spacings were used with temporal extensions N_t=4, 6, 8 and 10 (they correspond to lattice spacings a \\sim 0.3, 0.2, 0.15 and 0.12 fm). A new technique is presented, which --in contrast to earlier methods-- enables one to determine the equation of state at very large temperatures.

Z. Fodor

2007-11-02T23:59:59.000Z

57

QCD condensates in ADS/QCD  

E-Print Network [OSTI]

This paper focuses on some issues about condensates and renormalization in AdS/QCD models. In particular we consider the consistency of the AdS/QCD approach for scale dependent quantities as the chiral condensate questioned in some recent papers and the 4D meaning of the 5D cosmological constant in a model in which the QCD is dual to a 5D gravity theory. We will be able to give some arguments that the cosmological constant is related to the QCD gluon condensate.

Jacopo Bechi

2009-09-25T23:59:59.000Z

58

QCD landscape?  

E-Print Network [OSTI]

Just comparing with the scenario that the (3+1)-dimensional "real world" of the Calabi-Yau compactification has a tremendous landscape, we conjecture that a (4+1)-dimensional holographic theory may also hold a landscape of its vacua. Unlike the traditional studies of the AdS/CFT phenomenology where the vacua are always constructive, we discuss the proper holographic vacua and their flux compactification, starting from some general compact Einstein manifolds. The proper vacua should be restricted by (i) a consistent worldsheet theory that possesses the superconformal symmetry, (ii) some definite symmetries to keep/break the corresponding symmetries of the dual field theory, (iii) certain brane/flux configurations to cancel anomalies, and (iv) stabilities. We consider diverse fundamental parameters of the dual field theory, fixed by some special vacuum moduli. In an opposite way, if some field theory such as QCD holds an AdS dual, it may also possesses various fundamental parameters by an "landscape" of its vacuum. Different vacua may be adjacent with each other, and divided by domain walls. If the size of a single vacuum region is smaller than the visible universe, it may be testable. We discuss the consequences of this conjecture in the astrophysical environments, include but not limit to: (i) consistency with the critical energy density of the universe, (ii) the behaviors of cosmic rays, (iii) the stability and abundance of deuterons and other nuclei in the big-bang nucleosynthesis and the star burning scenarios, and (iv) the existence of strange/charm stars.

Cong-Xin Qiu

2009-11-23T23:59:59.000Z

59

QCDOC -Quantum Chromodynamics on a Chip at BNL | U.S. DOE Office...  

Office of Science (SC) Website

Nuclear Science Advisory Committee (NSAC) News & Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26Germantown Building 1000 Independence...

60

Murray Gell-Mann, the Eightfold Way, Quarks, and Quantum Chromodynamics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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to obtain the most current and comprehensive results.


61

QCDOC -Quantum Chromodynamics on a Chip at BNL | U.S. DOE Office of Science  

Office of Science (SC) Website

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched5 IndustrialIsadoreConnecticutPhotos of AEC Site UnderProgrammingPuerto

62

Color Glass Condensate in Schwinger–Keldysh QCD  

SciTech Connect (OSTI)

Within the Schwinger–Keldysh representation of many-body QCD, it is shown that the leading quantum corrections to the strong classical color field are “classical” in the sense that the fluctuation field still obeys the classical Jacobi-field equation, while the quantum effects solely reside in the fluctuations of the initial field configurations. Within this context, a systematic derivation of the JIMWLK renormalization group equation is presented. A clear identification of the correct form of gauge transformation rules and the correct form of the matter-field Lagrangian in the Schwinger–Keldysh QCD is also presented. -- Highlights: •Application of the Schwinger–Keldysh formalism to many-body QCD. •Clean separation of classical and quantum degrees of freedom. •Identification of the correct coupling between the gluon field and the color source. •Identification of the correct gauge transformation rules. •Sources of the classicality and quantum corrections to JIMWLK clarified.

Jeon, Sangyong, E-mail: jeon@physics.mcgill.ca

2014-01-15T23:59:59.000Z

63

Nuclear Physics from QCD  

E-Print Network [OSTI]

Effective field theories provide a bridge between QCD and nuclear physics. I discuss light nuclei from this perspective, emphasizing the role of fine-tuning.

U. van Kolck

2008-12-20T23:59:59.000Z

64

QCD results at CDF  

SciTech Connect (OSTI)

Recent QCD measurements from the CDF collaboration at the Tevatron are presented, together with future prospects as the luminosity increases. The measured inclusive jet cross section is compared to pQCD NLO predictions. Precise measurements on jet shapes and hadronic energy flows are compared to different phenomenological models that describe gluon emissions and the underlying event in hadron-hadron interactions.

Norniella, Olga; /Barcelona, IFAE

2005-01-01T23:59:59.000Z

65

Study of hadronic event-shape variables in multijet final states in pp collisions at ?s = 7 TeV  

E-Print Network [OSTI]

Event-shape variables, which are sensitive to perturbative and nonperturbative aspects of quantum chromodynamic (QCD) interactions, are studied in multijet events recorded in proton-proton collisions at ?s = 7 TeV. Events ...

Apyan, Aram

66

QCD (&) event generators  

SciTech Connect (OSTI)

Recent developments in QCD phenomenology have spurred on several improved approaches to Monte Carlo event generation, relative to the post-LEP state of the art. In this brief review, the emphasis is placed on approaches for (1) consistently merging fixed-order matrix element calculations with parton shower descriptions of QCD radiation, (2) improving the parton shower algorithms themselves, and (3) improving the description of the underlying event in hadron collisions.

Skands, Peter Z.; /Fermilab

2005-07-01T23:59:59.000Z

67

Combinatorics of Lattice QCD at Strong Coupling  

E-Print Network [OSTI]

Thermodynamics in the strong coupling limit of lattice QCD has features which may be similar to those of continuum QCD, such as a chiral critical end point and a nuclear liquid gas transition. Here I compare the combinatorics of staggered and Wilson fermions in the strong coupling limit for arbitrary number of colors and flavors. The partition functions can be considered as an expansions in hadronic spatial hoppings from the static limit, where both discretizations can be expressed via formulae with coefficients of distinct combinatorial interpretation. The corresponding multiplicites of hadronic states are evaluated using generalizations of Catalan numbers and Lucas polynomials. I outline how quantum Monte Carlo simulations can be carried out in general, and summarize recent results on the gauge corrections to the strong coupling limit.

Wolfgang Unger

2014-11-17T23:59:59.000Z

68

Quark-antiquark bound-state spectroscopy and QCD  

SciTech Connect (OSTI)

The discussion covers quarks as we know them, the classification of ordinary mesons in terms of constituent quarks, hidden charm states and charmed mesons, bottom quarks, positronium as a model for quarti q, quantum chromodynamics and its foundation in experiment, the charmonium model, the mass of states, fine structure and hyperfine structure, classification, widths of states, rate and multipolarity of gamma transitions, questions about bottom, leptonic widths and the determination of Q/sub b/, the mass splitting of the n/sup 3/S/sub 1/ states, the center of gravity of the masses of the n/sup 3/P; states, n/sup 3/ P; fine structure and classification, branching ratios for upsilon' ..-->.. tau chi/sub 6j/ and the tau cascade reactions, hyperfine splitting, and top. (GHT)

Bloom, E.D.

1982-11-01T23:59:59.000Z

69

Renormalization of Hamiltonian QCD  

SciTech Connect (OSTI)

We study to one-loop order the renormalization of QCD in the Coulomb gauge using the Hamiltonian formalism. Divergences occur which might require counter-terms outside the Hamiltonian formalism, but they can be cancelled by a redefinition of the Yang-Mills electric field.

Andrasi, A. [Rudjer Boskovic Institute, 10000 Zagreb (Croatia)], E-mail: aandrasi@rudjer.irb.hr; Taylor, John C. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge (United Kingdom)], E-mail: J.C.Taylor@damtp.cam.ac.uk

2009-10-15T23:59:59.000Z

70

Exponentially modified QCD coupling  

SciTech Connect (OSTI)

We present a specific class of models for an infrared-finite analytic QCD coupling, such that at large spacelike energy scales the coupling differs from the perturbative one by less than any inverse power of the energy scale. This condition is motivated by the Institute for Theoretical and Experimental Physics operator product expansion philosophy. Allowed by the ambiguity in the analytization of the perturbative coupling, the proposed class of couplings has three parameters. In the intermediate energy region, the proposed coupling has low loop-level and renormalization scheme dependence. The present modification of perturbative QCD must be considered as a phenomenological attempt, with the aim of enlarging the applicability range of the theory of the strong interactions at low energies.

Cvetic, Gorazd [Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso (Chile); Center of Subatomic Studies, UTFSM, Valparaiso (Chile); Valenzuela, Cristian [Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso (Chile)

2008-04-01T23:59:59.000Z

71

Introduction to lattice QCD  

SciTech Connect (OSTI)

The goal of the lectures on lattice QCD (LQCD) is to provide an overview of both the technical issues and the progress made so far in obtaining phenomenologically useful numbers. The lectures consist of three parts. The author`s charter is to provide an introduction to LQCD and outline the scope of LQCD calculations. In the second set of lectures, Guido Martinelli will discuss the progress they have made so far in obtaining results, and their impact on Standard Model phenomenology. Finally, Martin Luescher will discuss the topical subjects of chiral symmetry, improved formulation of lattice QCD, and the impact these improvements will have on the quality of results expected from the next generation of simulations.

Gupta, R.

1998-12-31T23:59:59.000Z

72

Magnetic susceptibility in QCD  

E-Print Network [OSTI]

Magnetic susceptibility in the deconfined phase of QCD is calculated in a closed form using a recent general expression for the quark gas pressure in magnetic field. Quark selfenergies are entering the result via Polyakov line factors and ensure the total paramagnetic effect, increasing with temperature. A generalized form of magnetic susceptibility in nonzero magnetic field suitable for experimental and lattice measurements is derived, showing a good agreement with available lattice data.

V. D. Orlovsky; Yu. A. Simonov

2014-05-12T23:59:59.000Z

73

The Massive Pulsar PSR J1614-2230: Linking Quantum Chromodynamics, Gamma-ray Bursts, and Gravitational Wave Astronomy  

E-Print Network [OSTI]

The recent measurement of the Shapiro delay in the radio pulsar PSR J1614-2230 yielded a mass of 1.97 +/- 0.04 M_sun, making it the most massive pulsar known to date. Its mass is high enough that, even without an accompanying measurement of the stellar radius, it has a strong impact on our understanding of nuclear matter, gamma-ray bursts, and the generation of gravitational waves from coalescing neutron stars. This single high mass value indicates that a transition to quark matter in neutron-star cores can occur at densities comparable to the nuclear saturation density only if the quarks are strongly interacting and are color superconducting. We further show that a high maximum neutron-star mass is required if short duration gamma-ray bursts are powered by coalescing neutron stars and, therefore, this mechanism becomes viable in the light of the recent measurement. Finally, we argue that the low-frequency (<= 500 Hz) gravitational waves emitted during the final stages of neutron-star coalescence encode the properties of the equation of state because neutron stars consistent with this measurement cannot be centrally condensed. This will facilitate the measurement of the neutron star equation of state with Advanced LIGO/Virgo.

Feryal Ozel; Dimitrios Psaltis; Scott Ransom; Paul Demorest; Mark Alford

2010-10-27T23:59:59.000Z

74

QCD and Light-Front Holography  

SciTech Connect (OSTI)

The soft-wall AdS/QCD model, modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics. The model predicts a zero-mass pion for zero-mass quarks and a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number N. Light-Front Holography maps the amplitudes which are functions of the fifth dimension variable z of anti-de Sitter space to a corresponding hadron theory quantized on the light front. The resulting Lorentz-invariant relativistic light-front wave equations are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. The result is to a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryon light-quark bound states, which in turn predict the behavior of the pion and nucleon form factors. The theory implements chiral symmetry in a novel way: the effects of chiral symmetry breaking increase as one goes toward large interquark separation, consistent with spectroscopic data, and the the hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. The soft-wall model also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function which agrees with the effective coupling {alpha}{sub g1} extracted from the Bjorken sum rule. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also reviewed.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.; ,

2010-10-27T23:59:59.000Z

75

Equilibrium Thermodynamics of Lattice QCD  

E-Print Network [OSTI]

Lattice QCD allows us to simulate QCD at non-zero temperature and/or densities. Such equilibrium thermodynamics calculations are relevant to the physics of relativistic heavy-ion collisions. I give a brief review of the field with emphasis on our work.

D. K. Sinclair

2007-02-03T23:59:59.000Z

76

QCD for Postgraduates (1/5)  

ScienceCinema (OSTI)

Modern QCD - Lecture 1 Starting from the QCD Lagrangian we will revisit some basic QCD concepts and derive fundamental properties like gauge invariance and isospin symmetry and will discuss the Feynman rules of the theory. We will then focus on the gauge group of QCD and derive the Casimirs CF and CA and some useful color identities.

None

2011-10-06T23:59:59.000Z

77

QCD Level Density from Maximum Entropy Method  

E-Print Network [OSTI]

We propose a method to calculate the QCD level density directly from the thermodynamic quantities obtained by lattice QCD simulations with the use of the maximum entropy method (MEM). Understanding QCD thermodynamics from QCD spectral properties has its own importance. Also it has a close connection to phenomenological analyses of the lattice data as well as experimental data on the basis of hadronic resonances. Our feasibility study shows that the MEM can provide a useful tool to study QCD level density.

Shinji Ejiri; Tetsuo Hatsuda

2005-09-24T23:59:59.000Z

78

Lattice QCD and Nuclear Physics  

SciTech Connect (OSTI)

A steady stream of developments in Lattice QCD have made it possible today to begin to address the question of how nuclear physics emerges from the underlying theory of strong interactions. Central role in this understanding play both the effective field theory description of nuclear forces and the ability to perform accurate non-perturbative calculations in lo w energy QCD. Here I present some recent results that attempt to extract important low energy constants of the effective field theory of nuclear forces from lattice QCD.

Konstantinos Orginos

2007-03-01T23:59:59.000Z

79

PHENOMENOLOGICAL STUDIES IN QCD RESUMMATION.  

SciTech Connect (OSTI)

We study applications of QCD soft-gluon resummations to electroweak annihilation cross sections. We focus on a formalism that allows to resume logarithmic corrections arising near partonic threshold and at small transverse momentum simultaneously.

KULESZA,A.; STERMAN,G.; VOGELSANG,W.

2002-09-01T23:59:59.000Z

80

Chiral dynamics in the low-temperature phase of QCD  

E-Print Network [OSTI]

We investigate the low-temperature phase of QCD and the crossover region with two light flavors of quarks. The chiral expansion around the point $(T,m=0)$ in the temperature vs. quark-mass plane indicates that a sharp real-time excitation exists with the quantum numbers of the pion. An exact sum rule is derived for the thermal modification of the spectral function associated with the axial charge density; the (dominant) pion pole contribution obeys the sum rule. We determine the two parameters of the pion dispersion relation using lattice QCD simulations and test the applicability of the chiral expansion. The time-dependent correlators are also analyzed using the Maximum Entropy Method, yielding consistent results. Finally, we test the predictions of the chiral expansion around the point $(T=0,m=0)$ for the temperature dependence of static observables.

Bastian B. Brandt; Anthony Francis; Harvey B. Meyer; Daniel Robaina

2014-06-21T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

QCD Thermodynamics on the Lattice: Recent Results  

E-Print Network [OSTI]

I give a brief introduction to the goals, challenges, and technical difficulties of lattice QCD thermodynamics and present some recent results from the HotQCD collaboration for the crossover temperature, equation of state, and other observables.

Carleton DeTar

2010-12-31T23:59:59.000Z

82

Lattice QCD with Domain Decomposition on Intel Xeon Phi Co-Processors  

SciTech Connect (OSTI)

The gap between the cost of moving data and the cost of computing continues to grow, making it ever harder to design iterative solvers on extreme-scale architectures. This problem can be alleviated by alternative algorithms that reduce the amount of data movement. We investigate this in the context of Lattice Quantum Chromodynamics and implement such an alternative solver algorithm, based on domain decomposition, on Intel Xeon Phi co-processor (KNC) clusters. We demonstrate close-to-linear on-chip scaling to all 60 cores of the KNC. With a mix of single- and half-precision the domain-decomposition method sustains 400-500 Gflop/s per chip. Compared to an optimized KNC implementation of a standard solver [1], our full multi-node domain-decomposition solver strong-scales to more nodes and reduces the time-to-solution by a factor of 5.

Heybrock, Simon; Joo, Balint; Kalamkar, Dhiraj D.; Smelyanskiy, Mikhail; Vaidyanathan, Karthikeyan; Wettig, Tilo; Dubey, Pradeep

2014-12-01T23:59:59.000Z

83

Critical QCD in Nuclear Collisions  

E-Print Network [OSTI]

A detailed study of correlated scalars, produced in collisions of nuclei and associated with the $\\sigma$-field fluctuations, $(\\delta \\sigma)^2= $, at the QCD critical point (critical fluctuations), is performed on the basis of a critical event generator (Critical Monte-Carlo) developed in our previous work. The aim of this analysis is to reveal suitable observables of critical QCD in the multiparticle environment of simulated events and select appropriate signatures of the critical point, associated with new and strong effects in nuclear collisions.

N. G. Antoniou; Y. F. Contoyiannis; F. K. Diakonos; G. Mavromanolakis

2005-05-20T23:59:59.000Z

84

Renormalization in Coulomb gauge QCD  

SciTech Connect (OSTI)

Research Highlights: > The Hamiltonian in the Coulomb gauge of QCD contains a non-linear Christ-Lee term. > We investigate the UV divergences from higher order graphs. > We find that they cannot be absorbed by renormalization of the Christ-Lee term. - Abstract: In the Coulomb gauge of QCD, the Hamiltonian contains a non-linear Christ-Lee term, which may alternatively be derived from a careful treatment of ambiguous Feynman integrals at 2-loop order. We investigate how and if UV divergences from higher order graphs can be consistently absorbed by renormalization of the Christ-Lee term. We find that they cannot.

Andrasi, A., E-mail: aandrasi@irb.hr ['Rudjer Boskovic' Institute, Zagreb (Croatia); Taylor, John C., E-mail: J.C.Taylor@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, University of Cambridge (United Kingdom)

2011-04-15T23:59:59.000Z

85

Applications of chiral perturbation theory to lattice QCD  

E-Print Network [OSTI]

These notes contain the written version of lectures given at the 2009 Les Houches Summer School "Modern perspectives in lattice QCD: Quantum field theory and high performance computing." The goal is to provide a pedagogical introduction to the subject, and not a comprehensive review. Topics covered include a general introduction, the inclusion of scaling violations in chiral perturbation theory, partial quenching and mixed actions, chiral perturbation theory with heavy kaons, and the effects of finite volume, both in the p- and epsilon-regimes.

Maarten Golterman

2010-05-06T23:59:59.000Z

86

QCD Spin Physics: Theoretical Overview  

SciTech Connect (OSTI)

We give an overview of some of the current activities and results in QCD spin physics. We focus on the helicity structure of the nucleon, where we highlight the results of a recent first global analysis of the helicity parton distributions, and on single-transverse spin asymmetries.

Vogelsang,W.

2008-11-09T23:59:59.000Z

87

Extremal black disks in QCD  

E-Print Network [OSTI]

We argue that in the high energy QCD a true black disk wave function necessarily contains many quarks. This corresponds to necessity of non-vacuum reggeon loops in formation of a black disk. The result comes from decomposition of the black disk S-matrix in characters on group manifold.

Alexey V. Popov

2008-05-12T23:59:59.000Z

88

Colour transparency: a novel test of QCD in nuclear interactions  

E-Print Network [OSTI]

Colour transparency is a cute and indispensable property of QCD as the gauge theory of strong interaction. CT tests of QCD consist of production of the perturbative small-sized hadronic state and measuring the strngth of its non-perturbative diffraction nteraction in a nuclear matter. The energy depenednce of the final- state interaction in a nuclear matter probes a dynamical evolution from the perturbative small-sized state to the full-sized nonperturbative hadron. QCD observables of CT experiments correspond to a novel mechanism of scanning of hadronic wave functions from the large nonperturbative to the small perturbative size. In these lectures, which are addressed to experimentalists and theorists, I discuss the principle ideas of CT physics and the physics potential of the hadron and electron facilities in the > 10 GeV energy range. The special effort was made to present the material in the pedagigical and self-consistent way, with an emphasis on the underlying rich quantum-mechanical interference phenomena.

N. N. Nikolaev

1993-04-20T23:59:59.000Z

89

The QCD Equation of State  

E-Print Network [OSTI]

Results for the equation of state in 2+1 flavor QCD at zero net baryon density using the Highly Improved Staggered Quark (HISQ) action by the HotQCD collaboration are presented. The strange quark mass was tuned to its physical value and the light (up/down) quark masses fixed to $m_l = 0.05m_s$ corresponding to a pion mass of 160 MeV in the continuum limit. Lattices with temporal extent $N_t=6$, 8, 10 and 12 were used. Since the cutoff effects for $N_t>6$ were observed to be small, reliable continuum extrapolations of the lattice data for the phenomenologically interesting temperatures range $130 \\mathord{\\rm MeV} < T < 400 \\mathord{\\rm MeV}$ could be performed. We discuss statistical and systematic errors and compare our results with other published works.

Tanmoy Bhattacharya; for the HotQCD collaboration

2015-01-30T23:59:59.000Z

90

The QCD Equation of State  

E-Print Network [OSTI]

Results for the equation of state in 2+1 flavor QCD at zero net baryon density using the Highly Improved Staggered Quark (HISQ) action by the HotQCD collaboration are presented. The strange quark mass was tuned to its physical value and the light (up/down) quark masses fixed to $m_l = 0.05m_s$ corresponding to a pion mass of 160 MeV in the continuum limit. Lattices with temporal extent $N_t=6$, 8, 10 and 12 were used. Since the cutoff effects for $N_t>6$ were observed to be small, reliable continuum extrapolations of the lattice data for the phenomenologically interesting temperatures range $130 \\mathord{\\rm MeV} < T < 400 \\mathord{\\rm MeV}$ could be performed. We discuss statistical and systematic errors and compare our results with other published works.

Bhattacharya, Tanmoy

2015-01-01T23:59:59.000Z

91

Transition Radiation in QCD matter  

E-Print Network [OSTI]

In ultrarelativistic heavy ion collisions a finite size QCD medium is created. In this paper we compute radiative energy loss to zeroth order in opacity by taking into account finite size effects. Transition radiation occurs on the boundary between the finite size medium and the vacuum, and we show that it lowers the difference between medium and vacuum zeroth order radiative energy loss relative to the infinite size medium case. Further, in all previous computations of light parton radiation to zeroth order in opacity, there was a divergence caused by the fact that the energy loss is infinite in the vacuum and finite in the QCD medium. We show that this infinite discontinuity is naturally regulated by including the transition radiation.

Magdalena Djordjevic

2005-12-22T23:59:59.000Z

92

FermiQCD: A tool kit for parallel lattice QCD applications  

SciTech Connect (OSTI)

We present here the most recent version of FermiQCD, a collection of C++ classes, functions and parallel algorithms for lattice QCD, based on Matrix Distributed Processing. FermiQCD allows fast development of parallel lattice applications and includes some SSE2 optimizations for clusters of Pentium 4 PCs.

Di Pierro, Massimo

2002-03-01T23:59:59.000Z

93

QCD for Postgraduates (2/5)  

ScienceCinema (OSTI)

Modern QCD - Lecture 2 We will start discussing the matter content of the theory and revisit the experimental measurements that led to the discovery of quarks. We will then consider a classic QCD observable, the R-ratio, and use it to illustrate the appearance of UV divergences and the need to renormalize the coupling constant of QCD. We will then discuss asymptotic freedom and confinement. Finally, we will examine a case where soft and collinear infrared divergences appear, will discuss the soft approximation in QCD and will introduce the concept of infrared safe jets.

None

2011-10-06T23:59:59.000Z

94

Hadronic Final States and QCD: Summary  

SciTech Connect (OSTI)

A summary of new experimental results and recent theoretical developments discussed in the 'Hadronic Final States and QCD' working group is presented.

Gehrmann, Thomas; /Zurich U.; Grindhammer, Guenter; /Munich, Max Planck Inst.; O'Dell, Vivian; /Fermilab; Walczak, Roman; /Oxford U.

2008-08-01T23:59:59.000Z

95

Light-Front Holographic QCD and Emerging Confinement  

E-Print Network [OSTI]

In this report we explore the remarkable connections between light-front dynamics, its holographic mapping to gravity in a higher-dimensional anti-de Sitter (AdS) space, and conformal quantum mechanics. This approach provides new insights into the origin of a fundamental mass scale and the physics underlying confinement dynamics in QCD in the limit of massless quarks. The result is a relativistic light-front wave equation for arbitrary spin with an effective confinement potential derived from a conformal action and its embedding in AdS space. This equation allows for the computation of essential features of hadron spectra in terms of a single scale. The light-front holographic methods described here gives a precise interpretation of holographic variables and quantities in AdS in terms of light-front variables and quantum numbers. This leads to a relation between the AdS wave functions and the boost-invariant light-front wave functions describing the internal structure of hadronic bound states in physical space-time. The pion is massless in the chiral limit and the excitation spectra of relativistic light-quark meson and baryon bound states lie on linear Regge trajectories with identical slopes in the radial and orbital quantum numbers. In the light-front holographic approach described here currents are expressed as an infinite sum of poles, and form factors as a product of poles. At large $q^2$ the form factor incorporates the correct power-law fall-off for hard scattering independent of the specific dynamics and is dictated by the twist. At low $q^2$ the form factor leads to vector dominance. The approach is also extended to include small quark masses. We briefly review in this report other holographic approaches to QCD, in particular top-down and bottom-up models based on chiral symmetry breaking. We also include a discussion of open problems and future applications.

Stanley J. Brodsky; Guy F. de Teramond; Hans Gunter Dosch; Joshua Erlich

2015-02-13T23:59:59.000Z

96

Two-photon collisions and QCD  

SciTech Connect (OSTI)

A critical review of the applications of QCD to low- and high-p/sub T/ interactions of two photons is presented. The advantages of the two-photon high-p/sub T/ tests over corresponding hadronic beam and/or target tests of QCD are given particular emphasis.

Gunion, J.F.

1980-05-01T23:59:59.000Z

97

Lattice QCD and NERSC requirements  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 CERNSemiconductor thinNanocrystallineQCD and

98

Jefferson Lab - QCD Evolution 2015  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFunInfraredJefferson Lab Click on theJames D. effortsOSTI,H19/0 en90/0 enQCD

99

Unconstrained Hamiltonian formulation of low energy QCD  

E-Print Network [OSTI]

Using a generalized polar decomposition of the gauge fields into gauge-rotation and gauge-invariant parts, which Abelianises the Non-Abelian Gauss-law constraints, an unconstrained Hamiltonian formulation of QCD can be achieved. The exact implementation of the Gauss laws reduces the colored spin-1 gluons and spin-1/2 quarks to unconstrained colorless spin-0, spin-1, spin-2 and spin-3 glueball fields and colorless Rarita-Schwinger fields. The obtained physical Hamiltonian naturally admits a systematic strong-coupling expansion in powers of \\lambda=g^{-2/3}, equivalent to an expansion in the number of spatial derivatives. The leading-order term corresponds to non-interacting hybrid-glueballs, whose low-lying spectrum can be calculated with high accuracy by solving the Schr\\"odinger-equation of the Dirac-Yang-Mills quantum mechanics of spatially constant fields (at the moment only for the 2-color case). The discrete glueball excitation spectrum shows a universal string-like behaviour with practically all excitation energy going in to the increase of the strengths of merely two fields, the "constant Abelian fields" corresponding to the zero-energy valleys of the chromomagnetic potential. Inclusion of the fermionic degrees of freedom significantly lowers the spectrum and allows for the study of the sigma meson. Higher-order terms in \\lambda lead to interactions between the hybrid-glueballs and can be taken into account systematically using perturbation theory, allowing for the study of IR-renormalisation and Lorentz invariance. The existence of the generalized polar decomposition used, the position of the zeros of the corresponding Jacobian (Gribov horizons), and the ranges of the physical variables can be investigated by solving a system of algebraic equations. It is exactly solvable for 1 spatial dimension and several numerical solutions can be found for 2 and 3 spatial dimensions.

Hans-Peter Pavel

2014-05-08T23:59:59.000Z

100

Nuclear Force from Lattice QCD  

E-Print Network [OSTI]

The first lattice QCD result on the nuclear force (the NN potential) is presented in the quenched level. The standard Wilson gauge action and the standard Wilson quark action are employed on the lattice of the size 16^3\\times 24 with the gauge coupling beta=5.7 and the hopping parameter kappa=0.1665. To obtain the NN potential, we adopt a method recently proposed by CP-PACS collaboration to study the pi pi scattering phase shift. It turns out that this method provides the NN potentials which are faithful to those obtained in the analysis of NN scattering data. By identifying the equal-time Bethe-Salpeter wave function with the Schroedinger wave function for the two nucleon system, the NN potential is reconstructed so that the wave function satisfies the time-independent Schroedinger equation. In this report, we restrict ourselves to the J^P=0^+ and I=1 channel, which enables us to pick up unambiguously the ``central'' NN potential V_{central}(r). The resulting potential is seen to posses a clear repulsive core of about 500 MeV at short distance (r < 0.5 fm). Although the attraction in the intermediate and long distance regions is still missing in the present lattice set-up, our method is appeared to be quite promising in reconstructing the NN potential with lattice QCD.

Noriyoshi ISHII; Sinya AOKI; Tetsuo HATSUDA

2006-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Recent Progress in Lattice QCD Thermodynamics  

E-Print Network [OSTI]

This review gives a critical assessment of the current state of lattice simulations of QCD thermodynamics and what it teaches us about hot hadronic matter. It outlines briefly lattice methods for studying QCD at nonzero temperature and zero baryon number density with particular emphasis on assessing and reducing cutoff effects. It discusses a variety of difficulties with methods for determining the transition temperature. It uses results reported recently in the literature and at this conference for illustration, especially those from a major study carried out by the HotQCD collaboration.

Carleton DeTar

2008-11-14T23:59:59.000Z

102

Chiral dynamics in the low-temperature phase of QCD  

E-Print Network [OSTI]

We investigate the low-temperature phase of QCD and the crossover region with two light flavors of quarks. The chiral expansion around the point $(T, m_q = 0)$ in the temperature vs. quark-mass plane indicates that a sharp real-time excitation exists with the quantum numbers of the pion. We determine its dispersion relation and test the applicability of the chiral expansion. The time-dependent correlators are also analyzed using the Maximum Entropy Method (MEM), yielding consistent results. Finally, we test the predictions of ordinary chiral perturbation theory around the point $(T = 0, m_q = 0)$ for the temperature dependence of static observables. Around the crossover temperature, we find that all quantities considered depend only mildly on the quark mass in the considered range 8MeV $\\leq \\bar{m}^{\\bar{\\text{MS}}} \\leq$ 15MeV.

Bastian B. Brandt; Anthony Francis; Harvey B. Meyer; Daniel Robaina

2014-10-22T23:59:59.000Z

103

Electroweak Symmetry Breaking via QCD  

E-Print Network [OSTI]

We propose a new mechanism to generate the electroweak scale within the framework of QCD, which is extended to include conformally invariant scalar degrees of freedom belonging to a larger irreducible representation of $SU(3)_c$. The electroweak symmetry breaking is triggered dynamically via the Higgs portal by the condensation of the colored scalar field around 1 TeV. The mass of the colored boson is restricted to be 350 GeV $\\lesssim m_S\\lesssim $ 3 TeV, with the upper bound obtained from perturbative renormalization group evolution. This implies that the colored boson can be produced at LHC. If the colored boson is electrically charged, the branching fraction of the Higgs decaying into two photons can slightly increase, and moreover, it can be produced at future linear colliders. Our idea of non-perturbative EW scale generation can serve as a new starting point for more realistic model building in solving the hierarchy problem.

Jisuke Kubo; Kher Sham Lim; Manfred Lindner

2014-09-01T23:59:59.000Z

104

Nuclear force in Lattice QCD  

E-Print Network [OSTI]

We perform the quenched lattice QCD analysis on the nuclear force (baryon-baryon interactions). We employ $20^3\\times 24$ lattice at $\\beta=5.7$ ($a\\simeq 0.19$ fm) with the standard gauge action and the Wilson quark action with the hopping parameters $\\kappa=0.1600, 0.1625, 0.1650$, and generate about 200 gauge configurations. We measure the temporal correlators of the two-baryon system which consists of heavy-light-light quarks. We extract the inter-baryon force as a function of the relative distance $r$. We also evaluate the contribution to the nuclear force from each ``Feynman diagram'' such as the quark-exchange diagram individually, and single out the roles of Pauli-blocking effects or quark exchanges in the inter-baryon interactions.

T. T. Takahashi; T. Doi; H. Suganuma

2006-01-05T23:59:59.000Z

105

QCD mechanisms for heavy particle production  

SciTech Connect (OSTI)

For very large pair mass, the production of heavy quarks and supersymmetric particles is expected to be governed by ACD fusion subprocesses. At lower mass scales other QCD mechanisms such as prebinding distortion and intrinsic heavy particle Fock states can become important, possibly accounting for the anomalies observed for charm hadroproduction. We emphasize the importance of final-state Coulomb interactions at low relative velocity in QCD and predict the existence of heavy narrow four quark resonances (c c-bar u u-bar) and (cc c-bar c-bar) in ..gamma gamma.. reactions. Coherent QCD contributions are discussed as a contribution to the non-additivity of nuclear structure functions and heavy particle production cross sections. We also predict a new type of amplitude zero for exclusive heavy meson pair production which follows from the tree-graph structure of QCD. 35 refs., 8 figs., 1 tab.

Brodsky, S.J.

1985-09-01T23:59:59.000Z

106

QCD for Postgraduates (4/5)  

ScienceCinema (OSTI)

Modern QCD - Lecture 4 We will consider some processes of interest at the LHC and will discuss the main elements of their cross-section calculations. We will also summarize the current status of higher order calculations.

None

2011-10-06T23:59:59.000Z

107

Reply to Isgur's comments on valence QCD  

SciTech Connect (OSTI)

We reply to Isgur's critique that is directed at some of the conclusions drawn from the lattice simulation of valence QCD, regarding the valence quark model and effective chiral theories. (c) 2000 The American Physical Society.

Liu, K. F. [SLAC, P.O. Box 4349, Stanford, California 94309 (United States) [SLAC, P.O. Box 4349, Stanford, California 94309 (United States); Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Dong, S. J. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)] [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Draper, T. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)] [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Sloan, J. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States) [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Spatial Technology, Boulder, Colorado 80301 (United States); Wilcox, W. [Department of Physics, Baylor University, Waco, Texas 76798 (United States)] [Department of Physics, Baylor University, Waco, Texas 76798 (United States); Woloshyn, R. M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada)] [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada)

2000-06-01T23:59:59.000Z

108

Probing QCD with Rare Charmless $B$ Decays  

SciTech Connect (OSTI)

Rare charmless hadronic B decays are a good testing ground for QCD. In this paper we describe a selection of new measurements made by the BABAR and BELLE collaborations.

Gradl, Wolfgang

2006-07-07T23:59:59.000Z

109

A Bayesian analysis of QCD sum rules  

SciTech Connect (OSTI)

A new technique has recently been developed, in which the Maximum Entropy Method is used to analyze QCD sum rules. This approach has the virtue of being able to directly generate the spectral function of a given operator, without the need of making an assumption about its specific functional form. To investigate whether useful results can be extracted within this method, we have first studied the vector meson channel, where QCD sum rules are traditionally known to provide a valid description of the spectral function. Our results show a significant peak in the region of the experimentally observed {rho}-meson mass, which is in agreement with earlier QCD sum rules studies and suggests that the Maximum Entropy Method is a strong tool for analyzing QCD sum rules.

Gubler, Philipp; Oka, Makoto [Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan)

2011-05-23T23:59:59.000Z

110

QCD as a topologically ordered system  

SciTech Connect (OSTI)

We argue that QCD belongs to a topologically ordered phase similar to many well-known condensed matter systems with a gap such as topological insulators or superconductors. Our arguments are based on an analysis of the so-called “deformed QCD” which is a weakly coupled gauge theory, but nevertheless preserves all the crucial elements of strongly interacting QCD, including confinement, nontrivial ? dependence, degeneracy of the topological sectors, etc. Specifically, we construct the so-called topological “BF” action which reproduces the well known infrared features of the theory such as non-dispersive contribution to the topological susceptibility which cannot be associated with any propagating degrees of freedom. Furthermore, we interpret the well known resolution of the celebrated U(1){sub A} problem where the would be ?{sup ?} Goldstone boson generates its mass as a result of mixing of the Goldstone field with a topological auxiliary field characterizing the system. We then identify the non-propagating auxiliary topological field of the BF formulation in deformed QCD with the Veneziano ghost (which plays the crucial role in resolution of the U(1){sub A} problem). Finally, we elaborate on relation between “string-net” condensation in topologically ordered condensed matter systems and long range coherent configurations, the “skeletons”, studied in QCD lattice simulations. -- Highlights: •QCD may belong to a topologically ordered phase similar to condensed matter (CM) systems. •We identify the non-propagating topological field in deformed QCD with the Veneziano ghost. •Relation between “string-net” condensates in CM systems and the “skeletons” in QCD lattice simulations is studied.

Zhitnitsky, Ariel R., E-mail: arz@physics.ubc.ca

2013-09-15T23:59:59.000Z

111

Thermodynamics of (2+1)-flavor QCD  

E-Print Network [OSTI]

We report on the status of our QCD thermodynamics project. It is performed on the QCDOC machine at Brookhaven National Laboratory and the APEnext machine at Bielefeld University. Using a 2+1 flavor formulation of QCD at almost realistic quark masses we calculated several thermodynamical quantities. In this proceeding we show the susceptibilites of the chiral condensate and the Polyakov loop, the static quark potential and the spatial string tension.

C. Schmidt; T. Umeda

2006-09-21T23:59:59.000Z

112

Recent QCD Studies at the Tevatron  

SciTech Connect (OSTI)

Since the beginning of Run II at the Fermilab Tevatron the QCD physics groups of the CDF and D0 experiments have worked to reach unprecedented levels of precision for many QCD observables. Thanks to the large dataset--over 3 fb{sup -1} of integrated luminosity recorded by each experiment--important new measurements have recently been made public and will be summarized in this paper.

Group, Robert Craig

2008-04-01T23:59:59.000Z

113

QCD and hard diffraction at the LHC  

SciTech Connect (OSTI)

As an introduction to QCD at the LHC the author gives an overview of QCD at the Tevatron, emphasizing the high Q{sup 2} frontier which will be taken over by the LHC. After describing briefly the LHC detectors the author discusses high mass diffraction, in particular central exclusive production of Higgs and vector boson pairs. The author introduces the FP420 project to measure the scattered protons 420m downstream of ATLAS and CMS.

Albrow, Michael G.; /Fermilab

2005-09-01T23:59:59.000Z

114

The origin of mass and the experiments on future high energy accelerators  

E-Print Network [OSTI]

The visible universe - it is the universe of nucleons and electrons. The appearance of nucleon mass is caused by the violation of chiral symmetry in quantum chromodynamics (QCD). For this reason, the experiments on high energy accelerators cannot shed light on the origin of the matter in the visible universe. The origin of the mass of matter will be clarified, when the mechanism of chiral symmetry violation in QCD will be elucidated.

B. L. Ioffe

2006-01-30T23:59:59.000Z

115

Glimpsing Colour in a World of Black and White  

E-Print Network [OSTI]

The past 40 years have taught us that nucleons are built of constituents that carry colour charges with interactions governed by Quantum Chromodynamics (QCD). How experiments (past, present and future) at Jefferson Lab probe colourless nuclei to map out these internal colour degrees of freedom is presented. When combined with theoretical calculations, these will paint a picture of how the confinement of quarks and gluons, and the structure of the QCD vacuum, determine the properties of all (light) strongly interacting states.

M. R. Pennington

2011-10-18T23:59:59.000Z

116

Electromagnetically superconducting phase of QCD vacuum induced by strong magnetic field  

SciTech Connect (OSTI)

In this talk we discuss our recent suggestion that the QCD vacuum in a sufficiently strong magnetic field (stronger than 10{sup 16} Tesla) may undergo a spontaneous transition to an electromagnetically superconducting state. The possible superconducting state is anisotropic (the vacuum exhibits superconductivity only along the axis of the uniform magnetic field) and inhomogeneous (in the transverse directions the vacuum structure shares similarity with the Abrikosov lattice of an ordinary type-II superconductor). The electromagnetic superconductivity of the QCD vacuum is suggested to occur due to emergence of specific quark-antiquark condensates which carry quantum numbers of electrically charged rho mesons. A Lorentz-covariant generalization of the London transport equations for the magnetic-field-induced superconductivity is given.

Chernodub, M. N. [CNRS, Laboratoire de Mathematiques et Physique Theorique, Universite Francois-Rabelais Tours, Federation Denis Poisson, Parc de Grandmont, 37200 Tours (France); Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent (Belgium)

2011-05-23T23:59:59.000Z

117

Bound states in the physical QCD sub 2  

SciTech Connect (OSTI)

Different variants of the physical QCD{sub 2} are analyzed. The role of the chiral background field in the theory is stressed. A massive bound state creating operator in the massless physical QCD{sub 2} is constructed.

Saradzhev, F.M. (Dept. of Matter Structure, Faculty of Physics, Azerbaijan State Univ., Baku 602, Azerbaijan (SU))

1990-07-10T23:59:59.000Z

118

Exploration of nucleon structure in lattice QCD with chiral quarks  

E-Print Network [OSTI]

In this work, we calculate various nucleon structure observables using the fundamental theory of quarks and gluons, QCD, simulated on a lattice. In our simulations, we use the full QCD action including Nf = 2+ 1 dynamical ...

Syritsyn, Sergey Nikolaevich

2010-01-01T23:59:59.000Z

119

The Electron-Ion Collider Science Case  

E-Print Network [OSTI]

For the first time, physicists are in the position to precisely study a fully relativistic quantum field theory: Quantum ChromoDynamics (QCD). QCD is a central element of the Standard Model and provides the theoretical framework for understanding the strong interaction. This demands a powerful new electron microscope to probe the virtual particles of QCD. Ab initio calculations using lattice gauge theory on the world's most powerful supercomputers are essential for comparison with the data. The new accelerator and computing techniques demand aggressive development of challenging, innovative technologies.

Richard G. Milner

2014-05-27T23:59:59.000Z

120

QCD and Light-Front Dynamics  

SciTech Connect (OSTI)

AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its {beta}-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

Brodsky, Stanley J.; de Teramond, Guy F.; /SLAC /Southern Denmark U., CP3-Origins /Costa Rica U.

2011-01-10T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

QCDLAB: Designing Lattice QCD Algorithms with MATLAB  

E-Print Network [OSTI]

This paper introduces QCDLAB, a design and research tool for lattice QCD algorithms. The tool, a collection of MATLAB functions, is based on a ``small-code'' and a ``minutes-run-time'' algorithmic design philosophy. The present version uses the Schwinger model on the lattice, a great simplification, which shares many features and algorithms with lattice QCD. A typical computing project using QCDLAB is characterised by short codes, short run times, and the ability to make substantial changes in a few seconds. QCDLAB 1.0 can be downloaded from the QCDLAB project homepage {\\tt http://phys.fshn.edu.al/qcdlab.html}.

Artan Borici

2006-10-09T23:59:59.000Z

122

Quark mass thresholds in QCD thermodynamics  

E-Print Network [OSTI]

We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high temperature QCD. The indication from leading order that the charm quark plays a visible role at surprisingly low temperatures, is confirmed. We also sketch a way to obtain phenomenological estimates relevant for generic expansion rate computations at temperatures between the QCD and electroweak scales, pointing out where improvements over the current knowledge are particularly welcome.

M. Laine; Y. Schroder

2006-05-05T23:59:59.000Z

123

Experimental Study of Nucleon Structure and QCD  

SciTech Connect (OSTI)

Overview of Experimental Study of Nucleon Structure and QCD, with focus on the spin structure. Nucleon (spin) Structure provides valuable information on QCD dynamics. A decade of experiments from JLab yields these exciting results: (1) valence spin structure, duality; (2) spin sum rules and polarizabilities; (3) precision measurements of g{sub 2} - high-twist; and (4) first neutron transverse spin results - Collins/Sivers/A{sub LT}. There is a bright future as the 12 GeV Upgrade will greatly enhance our capability: (1) Precision determination of the valence quark spin structure flavor separation; and (2) Precision extraction of transversity/tensor charge/TMDs.

Jian-Ping Chen

2012-03-01T23:59:59.000Z

124

Automation of one-loop QCD corrections  

E-Print Network [OSTI]

We present the complete automation of the computation of one-loop QCD corrections, including UV renormalization, to an arbitrary scattering process in the Standard Model. This is achieved by embedding the OPP integrand reduction technique, as implemented in CutTools, into the MadGraph framework. By interfacing the tool so constructed, which we dub MadLoop, with MadFKS, the fully automatic computation of any infrared-safe observable at the next-to-leading order in QCD is attained. We demonstrate the flexibility and the reach of our method by calculating the production rates for a variety of processes at the 7 TeV LHC.

Valentin Hirschi; Rikkert Frederix; Stefano Frixione; Maria Vittoria Garzelli; Fabio Maltoni; Roberto Pittau

2013-05-14T23:59:59.000Z

125

Low-energy holographic models for QCD  

E-Print Network [OSTI]

We consider the bottom-up holographic models for QCD which contain the ultraviolet (UV) cutoff. Such models are supposed to describe exclusively the low-energy sector of QCD. The introduction of UV cutoff in the soft wall model is shown to result in a model with qualitatively different predictions. The ensuing model seems to be able to incorporate the constituent quark mass. It is also demonstrated that in order to reproduce the results of the usual soft wall model for the vector and higher spin mesons in the presence of the UV cutoff one can consider the flat bulk space with a modified dilaton background.

S. S. Afonin

2011-04-09T23:59:59.000Z

126

Exact beta function from the holographic loop equation of large-N QCD_4  

E-Print Network [OSTI]

We construct and study a previously defined quantum holographic effective action whose critical equation implies the holographic loop equation of large-N QCD_4 for planar self-avoiding loops in a certain regularization scheme. We extract from the effective action the exact beta function in the given scheme. For the Wilsonean coupling constant the beta function is exacly one loop and the first coefficient agrees with its value in perturbation theory. For the canonical coupling constant the exact beta function has a NSVZ form and the first two coefficients agree with their value in perturbation theory.

Marco Bochicchio

2007-06-08T23:59:59.000Z

127

Dynamical holographic QCD with area-law confinement and linear Regge trajectories  

SciTech Connect (OSTI)

We construct a new solution of five-dimensional gravity coupled to a dilaton which encodes essential features of holographic QCD backgrounds dynamically. In particular, it implements linear confinement, i.e., the area-law behavior of the Wilson loop, by means of a dynamically deformed anti-de Sitter metric. The predicted square masses of the light-flavored natural-parity mesons and their excitations lie on linear trajectories of an approximately universal slope with respect to both radial and spin quantum numbers and are in satisfactory agreement with experimental data.

Paula, Wayne de; Frederico, Tobias [Departamento de Fisica, Instituto Tecnologico de Aeronautica, 12228-900 Sao Jose dos Campos, Sao Paulo (Brazil); Forkel, Hilmar [Departamento de Fisica, Instituto Tecnologico de Aeronautica, 12228-900 Sao Jose dos Campos, Sao Paulo (Brazil); Institut fuer Theoretische Physik, Universitaet Heidelberg, D-69120 Heidelberg (Germany); Institut fuer Physik, Humboldt-Universitaet zu Berlin, D-12489 Berlin (Germany); Beyer, Michael [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany)

2009-04-01T23:59:59.000Z

128

QCD Evolution of Helicity and Transversity TMDs  

SciTech Connect (OSTI)

We examine the QCD evolution of the helicity and transversity parton distribution functions when including also their dependence on transverse momentum. Using an appropriate definition of these polarized transverse momentum distributions (TMDs), we describe their dependence on the factorization scale and rapidity cutoff, which is essential for phenomenological applications.

Prokudin, Alexei [JLAB, Newport News, VA (United States)

2014-01-01T23:59:59.000Z

129

QCD thermodynamics with dynamical overlap fermions  

E-Print Network [OSTI]

We study QCD thermodynamics using two flavors of dynamical overlap fermions with quark masses corresponding to a pion mass of 350 MeV. We determine several observables on N_t=6 and 8 lattices. All our runs are performed with fixed global topology. Our results are compared with staggered ones and a nice agreement is found.

S. Borsanyi; Y. Delgado; S. Durr; Z. Fodor; S. D. Katz; S. Krieg; T. Lippert; D. Nogradi; K. K. Szabo

2012-08-02T23:59:59.000Z

130

QCD for Postgraduates (3/5)  

ScienceCinema (OSTI)

Modern QCD - Lecture 3 We will introduce processes with initial-state hadrons and discuss parton distributions, sum rules, as well as the need for a factorization scale once radiative corrections are taken into account. We will then discuss the DGLAP equation, the evolution of parton densities, as well as ways in which parton densities are extracted from data.

None

2011-10-06T23:59:59.000Z

131

Performance of machines for lattice QCD simulations  

E-Print Network [OSTI]

We review the architecture of massively parallel machines used for lattice QCD simulations and present benchmarks for the performance of popular algorithms on these platforms. We cover commercial supercomputers, PC clusters, and custom-designed machines. We also speculate on future developments.

Tilo Wettig

2005-09-23T23:59:59.000Z

132

Quark condensate in two-flavor QCD  

E-Print Network [OSTI]

We compute the condensate in QCD with two flavors of dynamical fermions using numerical simulation. The simulations use overlap fermions, and the condensate is extracted by fitting the distribution of low lying eigenvalues of the Dirac operator in sectors of fixed topological charge to the predictions of Random Matrix Theory.

Thomas DeGrand; Zhaofeng Liu; Stefan Schaefer

2006-11-03T23:59:59.000Z

133

Heavy quark thermodynamics in full QCD  

E-Print Network [OSTI]

We analyze the large-distance behaviour of static quark-anti-quark pair correlations in QCD. The singlet free energy is calculated and the entropy contribution to it is identified allowing us to calculate the excess internal energy. The free energy has a sharp drop in the critical region, leading to sharp peaks in both excess entropy and internal energy.

Konstantin Petrov; RBC-Bielefeld Collaboration

2007-01-22T23:59:59.000Z

134

Nonperturbative QCD corrections to electroweak observables  

SciTech Connect (OSTI)

Nonperturbative QCD corrections are important to many low-energy electroweak observables, for example the muon magnetic moment. However, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. Currently, these hadronic contributions are accounted for by a combination of experimental measurements and phenomenological modeling but ideally should be calculated from first principles. Recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice QCD methods. To illustrate this, we will examine the lattice computation of the leading-order QCD corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. We will then continue with several examples that demonstrate the potential impact of the new approach: the leading-order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next-to-leading-order corrections for the muon magnetic moment. Along the way, we will mention applications to the Adler function, the determination of the strong coupling constant and QCD corrections to muonic-hydrogen.

Dru B Renner, Xu Feng, Karl Jansen, Marcus Petschlies

2011-12-01T23:59:59.000Z

135

Infrared Scales and Factorization in QCD  

E-Print Network [OSTI]

Effective field theory methods are used to study factorization of the deep inelastic scattering cross-section. The cross-section is shown to factor in QCD, even though it does not factor in perturbation theory for some choices of the infrared regulator. Messenger modes are not required in soft-collinear effective theory for deep inelastic scattering as x -> 1.

Aneesh V. Manohar

2005-12-14T23:59:59.000Z

136

Recent QCD-related results from ATLAS  

E-Print Network [OSTI]

In this presentation I will give a review of QCD-related results obtained and published by ATLAS. I will cover measurement results constraining parton distribution functions, soft and hard partonic resummation, higher order matrix element calculations, their matching to parton shower, and vector boson plus heavy flavor jets.

Beauchemin, Pierre-Hugues; The ATLAS collaboration

2015-01-01T23:59:59.000Z

137

Visualization Tools for Lattice QCD - Final Report  

SciTech Connect (OSTI)

Our research project is about the development of visualization tools for Lattice QCD. We developed various tools by extending existing libraries, adding new algorithms, exposing new APIs, and creating web interfaces (including the new NERSC gauge connection web site). Our tools cover the full stack of operations from automating download of data, to generating VTK #12;files (topological charge, plaquette, Polyakov lines, quark and meson propagators, currents), to turning the VTK #12;files into images, movies, and web pages. Some of the tools have their own web interfaces. Some Lattice QCD visualization have been created in the past but, to our knowledge, our tools are the only ones of their kind since they are general purpose, customizable, and relatively easy to use. We believe they will be valuable to physicists working in the #12;field. They can be used to better teach Lattice QCD concepts to new graduate students; they can be used to observe the changes in topological charge density and detect possible sources of bias in computations; they can be used to observe the convergence of the algorithms at a local level and determine possible problems; they can be used to probe heavy-light mesons with currents and determine their spatial distribution; they can be used to detect corrupted gauge configurations. There are some indirect results of this grant that will benefit a broader audience than Lattice QCD physicists.

Massimo Di Pierro

2012-03-15T23:59:59.000Z

138

Electron Ion Collider: The Next QCD Frontier  

E-Print Network [OSTI]

Electron Ion Collider: The Next QCD Frontier Executive Summary Understanding the glue that binds us . . . . . . . . . . . . . . . . . . . . 7 1.2.3 Physics Possibilities at the Intensity Frontier . . . . . . . . . . . . . 10 1 charge. This causes the gluons to interact with each other, generating nearly all the mass of the nucleon

Homes, Christopher C.

139

On-Shell Methods in Perturbative QCD  

E-Print Network [OSTI]

We review on-shell methods for computing multi-parton scattering amplitudes in perturbative QCD, utilizing their unitarity and factorization properties. We focus on aspects which are useful for the construction of one-loop amplitudes needed for phenomenological studies at the Large Hadron Collider.

Zvi Bern; Lance J. Dixon; David A. Kosower

2007-05-30T23:59:59.000Z

140

Quantum Simulation  

E-Print Network [OSTI]

Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry and cosmology. Quantum simulation could be implemented using quantum computers, but also with simpler, analog devices that would require less control, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar molecules, electrons in semiconductors, superconducting circuits, nuclear spins and photons have been proposed as quantum simulators. This review outlines the main theoretical and experimental aspects of quantum simulation and emphasizes some of the challenges and promises of this fast-growing field.

I. M. Georgescu; S. Ashhab; Franco Nori

2014-03-13T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Lattice QCD Thermodynamics with Physical Quark Masses  

E-Print Network [OSTI]

Over the past few years new physics methods and algorithms as well as the latest supercomputers have enabled the study of the QCD thermodynamic phase transition using lattice gauge theory numerical simulations with unprecedented control over systematic errors. This is largely a consequence of the ability to perform continuum extrapolations with physical quark masses. Here we review recent progress in lattice QCD thermodynamics, focussing mainly on results that benefit from the use of physical quark masses: the crossover temperature, the equation of state, and fluctuations of the quark number susceptibilities. In addition, we place a special emphasis on calculations that are directly relevant to the study of relativistic heavy ion collisions at RHIC and the LHC.

R. A. Soltz; C. DeTar; F. Karsch; Swagato Mukherjee; P. Vranas

2015-02-08T23:59:59.000Z

142

Hadronization of QCD and effective interactions  

SciTech Connect (OSTI)

An introductory treatment of hadronization through functional integral calculus and bifocal Bose fields is given. Emphasis is placed on the utility of this approach for providing a connection between QCD and effective hadronic field theories. The hadronic interactions obtained by this method are nonlocal due to the QCD substructure, yet, in the presence of an electromagnetic field, maintain the electromagnetic gauge invariance manifest at the quark level. A local chiral model which is structurally consistent with chiral perturbation theory is obtained through a derivative expansion of the nonlocalities with determined, finite coefficients. Tree-level calculations of the pion form factor and {pi} {minus} {pi} scattering, which illustrate the dual constituent-quark-chiral-model nature of this approach, are presented.

Frank, M.R.

1994-07-01T23:59:59.000Z

143

Nuclear physics from strong coupling QCD  

E-Print Network [OSTI]

The strong coupling limit (beta_gauge = 0) of QCD offers a number of remarkable research possibilities, of course at the price of large lattice artifacts. Here, we determine the complete phase diagram as a function of temperature T and baryon chemical potential mu_B, for one flavor of staggered fermions in the chiral limit, with emphasis on the determination of a tricritical point and on the T ~ 0 transition to nuclear matter. The latter is known to happen for mu_B substantially below the baryon mass, indicating strong nuclear interactions in QCD at infinite gauge coupling. This leads us to studying the properties of nuclear matter from first principles. We determine the nucleon-nucleon potential in the strong coupling limit, as well as masses m_A of nuclei as a function of their atomic number A. Finally, we clarify the origin of nuclear interactions at strong coupling, which turns out to be a steric effect.

Michael Fromm; Philippe de Forcrand

2009-12-14T23:59:59.000Z

144

Infrared instability from nonlinear QCD evolution  

E-Print Network [OSTI]

Using the Balitsky-Kovchegov (BK) equation as an explicit example, we show that nonlinear QCD evolution leads to an instability in the propagation toward the infrared of the gluon transverse momentum distribution, if one starts with a state with an infrared cut-off. This effect takes the mathematical form of rapidly moving traveling wave solutions of the BK equation, which we investigate by numerical simulations. These traveling wave solutions are different from those governing the transition to saturation, which propagate towards the ultraviolet. The infrared wave speed, formally infinite for the leading order QCD kernel, is determined by higher order corrections. This mechanism could play a role in the rapid decrease of the mean free path in the Color Glass Condensate scenario for heavy ion collisions.

R. Enberg; R. Peschanski

2006-01-13T23:59:59.000Z

145

MAGNETIC FIELDS FROM QCD PHASE TRANSITIONS  

SciTech Connect (OSTI)

We study the evolution of QCD phase transition-generated magnetic fields (MFs) in freely decaying MHD turbulence of the expanding universe. We consider an MF generation model that starts from basic non-perturbative QCD theory and predicts stochastic MFs with an amplitude of the order of 0.02 {mu}G and small magnetic helicity. We employ direct numerical simulations to model the MHD turbulence decay and identify two different regimes: a 'weakly helical' turbulence regime, when magnetic helicity increases during decay, and 'fully helical' turbulence, when maximal magnetic helicity is reached and an inverse cascade develops. The results of our analysis show that in the most optimistic scenario the magnetic correlation length in the comoving frame can reach 10 kpc with the amplitude of the effective MF being 0.007 nG. We demonstrate that the considered model of magnetogenesis can provide the seed MF for galaxies and clusters.

Tevzadze, Alexander G. [Faculty of Exact and Natural Sciences, Javakhishvili Tbilisi State University, 1 Chavchavadze Avenue, Tbilisi 0128 (Georgia); Kisslinger, Leonard; Kahniashvili, Tina [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Brandenburg, Axel, E-mail: aleko@tevza.org [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)

2012-11-01T23:59:59.000Z

146

Dual superconducting properties of the QCD vacuum  

E-Print Network [OSTI]

A consistent description of the confining QCD vacuum as a dual superconductor requires a determination of fundamental parameters such as the superconductor correlation length $\\xi$ and the field penetration depth $\\lambda$, which determine whether the superconductor is of type I or type II. We illustrate preliminary results of a lattice determination of $\\xi$ for the case of pure Yang-Mills with two colors, obtained by measuring the temporal correlator of a disorder parameter detecting dual superconductivity.

A. D'Alessandro; M. D'Elia

2005-10-27T23:59:59.000Z

147

Electromagnetic and spin polarisabilities in lattice QCD  

E-Print Network [OSTI]

We discuss the extraction of the electromagnetic and spin polarisabilities of nucleons from lattice QCD. We show that the external field method can be used to measure all the electromagnetic and spin polarisabilities including those of charged particles. We then turn to the extrapolations required to connect such calculations to experiment in the context of chiral perturbation theory, finding a strong dependence on the lattice volume and quark masses.

W. Detmold; B. C. Tiburzi; A. Walker-Loud

2006-10-02T23:59:59.000Z

148

Evaluation of QCD sum rules for HADES  

E-Print Network [OSTI]

QCD sum rules are evaluated at finite nucleon densities and temperatures to determine the change of pole mass parameters for the lightest vector mesons $\\rho$, $\\omega$ and $\\phi$ in a strongly interacting medium at conditions relevant for the starting experiments at HADES. The role of the four-quark condensate is highlighted. A few estimates (within a fire ball model and BUU calculations) of dilepton spectra in heavy-ion collisions at 1 AGeV are presented.

S. Zschocke; B. Kampfer; O. P. Pavlenko; Gy. Wolf

2002-02-21T23:59:59.000Z

149

On-shell Recursion Relations for n-point QCD  

E-Print Network [OSTI]

We present on the use of on-shell recursion relations. These can be used not only for calculating tree amplitudes, including those with masses, but also to compute analytically the missing rational terms of one-loop QCD amplitudes. Combined with the cut-containing pieces calculated using a unitarity approach complete one-loop QCD amplitudes can be derived. This approach is discussed in the context of the adjacent 2-minus all-multiplicity QCD gluon amplitude.

Darren Forde

2006-08-03T23:59:59.000Z

150

Full CKM matrix with lattice QCD  

SciTech Connect (OSTI)

The authors show that it is now possible to fully determine the CKM matrix, for the first time, using lattice QCD. |V{sub cd}|, |V{sub cs}|, |V{sub ub}|, |V{sub cb}| and |V{sub us}| are, respectively, directly determined with the lattice results for form factors of semileptonic D {yields} {pi}lv, D {yields} Klv, B {yields} {pi}lv, B {yields} Dlv and K {yields} {pi}lv decays. The error from the quenched approximation is removed by using the MILC unquenced lattice gauge configurations, where the effect of u, d and s quarks is included. The error from the ''chiral'' extrapolation (m{sub l} {yields} m{sub ud}) is greatly reduced by using improved staggered quarks. The accuracy is comparable to that of the Particle Data Group averages. In addition, |V{sub ud}|, |V{sub ts}|, |V{sub ts}| and |V{sub td}| are determined by using unitarity of the CKM matrix and the experimental result for sin (2{beta}). In this way, they obtain all 9 CKM matrix elements, where the only theoretical input is lattice QCD. They also obtain all the Wolfenstein parameters, for the first time, using lattice QCD.

Okamoto, Masataka; /Fermilab

2004-12-01T23:59:59.000Z

151

QCD Factorization for heavy quarkonium production at collider energies  

E-Print Network [OSTI]

In this talk, I briefly review several models of the heavy quarkonium production at collider energies, and discuss the status of QCD factorization for these production models.

Jian-Wei Qiu

2006-10-31T23:59:59.000Z

152

QCD phase diagram from the lattice at strong coupling  

E-Print Network [OSTI]

The phase diagram of lattice QCD in the strong coupling limit can be measured in the full $\\mu$-$T$ plane, also in the chiral limit. In particular, the phase diagram in the chiral limit features a tricritical point at some $(\\mu_c,T_c)$. This point may be related to the critical end point expected in the QCD phase diagram. We discuss the gauge corrections to the phase diagram at strong coupling and compare our findings with various possible scenarios in continuum QCD. We comment on the possibility that the tricritical point at strong coupling is connected to the tricritical point in the continuum, massless QCD.

de Forcrand, Philippe; Unger, Wolfgang

2015-01-01T23:59:59.000Z

153

QCD and High Energy Interactions: Moriond 2014 Theory Summary  

E-Print Network [OSTI]

This article summarizes new theoretical developments, ideas and results that were presented at the 2014 Moriond "QCD and High Energy Interactions".

Thomas Gehrmann

2014-06-20T23:59:59.000Z

154

Lattice analysis for the energy scale of QCD phenomena  

E-Print Network [OSTI]

We formulate a new framework in lattice QCD to study the relevant energy scale of QCD phenomena. By considering the Fourier transformation of link variable, we can investigate the intrinsic energy scale of a physical quantity nonperturbatively. This framework is broadly available for all lattice QCD calculations. We apply this framework for the quark-antiquark potential and meson masses in quenched lattice QCD. The gluonic energy scale relevant for the confinement is found to be less than 1 GeV in the Landau or Coulomb gauge.

Arata Yamamoto; Hideo Suganuma

2008-12-09T23:59:59.000Z

155

Quantum Machines  

E-Print Network [OSTI]

We discuss quantum information processing machines. We start with single purpose machines that either redistribute quantum information or identify quantum states. We then move on to machines that can perform a number of functions, with the function they perform being determined by a program, which is itself a quantum state. Examples of both deterministic and probabilistic programmable machines are given, and we conclude with a discussion of the utility of quantum programs.

Mark Hillery; Vladimir Buzek

2009-03-24T23:59:59.000Z

156

Energy Conservation Constraints on Multiplicity Correlations in QCD Jets  

E-Print Network [OSTI]

We compute analytically the effects of energy conservation on the self-similar structure of parton correlations in QCD jets. The calculations are performed both in the constant and running coupling cases. It is shown that the corrections are phenomenologically sizeable. On a theoretical ground, energy conservation constraints preserve the scaling properties of correlations in QCD jets beyond the leading log approximation.

J. -L. Meunier; R. Peschanski

1996-03-13T23:59:59.000Z

157

heplat/9311002 Full QCD on APE100 Machines.  

E-Print Network [OSTI]

hep­lat/9311002 Full QCD on APE100 Machines. Stefano ANTONELLI, Marco BELLACCI, Andrea DONINI of QCD with two flavours of dynamical Wilson fermions using the Hybrid Monte Carlo Algorithm (HMCA on the lattice by means of Monte Carlo methods have become an important tool to understand and pre­ dict non

Roma "La Sapienza", Università di

158

LATTICE QCD AT FINITE TEMPERATURE AND DENSITY.  

SciTech Connect (OSTI)

With the operation of the RHIC heavy ion program, the theoretical understanding of QCD at finite temperature and density has become increasingly important. Though QCD at finite temperature has been extensively studied using lattice Monte-Carlo simulations over the past twenty years, most physical questions relevant for RHIC (and future) heavy ion experiments remain open. In lattice QCD at finite temperature and density there have been at least two major advances in recent years. First, for the first time calculations of real time quantities, like meson spectral functions have become available. Second, the lattice study of the QCD phase diagram and equation of state have been extended to finite baryon density by several groups. Both issues were extensively discussed in the course of the workshop. A real highlight was the study of the QCD phase diagram in (T, {mu})-plane by Z. Fodor and S. Katz and the determination of the critical end-point for the physical value of the pion mass. This was the first time such lattice calculations at, the physical pion mass have been performed. Results by Z Fodor and S. Katz were obtained using a multi-parameter re-weighting method. Other determinations of the critical end point were also presented, in particular using a Taylor expansion around {mu} = 0 (Bielefeld group, Ejiri et al.) and using analytic continuation from imaginary chemical potential (Ph. de Forcrand and O. Philipsen). The result based on Taylor expansion agrees within errors with the new prediction of Z. Fodor and S. Katz, while methods based on analytic continuation still predict a higher value for the critical baryon density. Most of the thermodynamics studies in full QCD (including those presented at this workshop) have been performed using quite coarse lattices, a = 0.2-0.3 fm. Therefore one may worry about cutoff effects in different thermodynamic quantities, like the transition temperature T{sub tr}. At the workshop U. Heller presented a study of the transition temperature for three different lattice spacings and performed a continuum extrapolation of T{sub tr} for the first time. Lattice calculations of the meson spectral functions were presented by M. Asakawa, S. Datta, E. Laermann and H. Matsufuru. These show that charmonia ground states ({eta}{sub c} and J/{psi}) continue to exist in the plasma at least up to a temperature of 1.7 T{sub tr}. At what temperature charmonia states cease to exist is not yet clear. Calculations presented by M. Asakawa show dissolution of the J/{psi} at T = 1.7 T{sub tr}, while the analysis presented H. Matsufuru provided evidence that ground state charmonia still exist at this temperature. S. Datta argued that the ground state charmonia is likely to dissolve only for temperatures T > 2.25 T{sub tr}, while the P-states are dissociated at, 1.1 T{sub tr}. It is also very interesting that, even in the case of light quarks, meson spectral functions show a resonance-like structure in the plasma phase (talk by E. Laermann). Finally attempts to calculate transport properties in the Quark Gluon Plasma were presented by S. Gupta. The workshop devoted special attention to the finite temperature modification of inter-quark forces and color screening, another area where considerable progress has been made in recent years (talks by 0. Kaczmarek, K. Petrov, O. Philipsen and F. Zantow). Many other new theoretical developments which cannot be discussed here were also presented on the workshop. Altogether the workshop was a great success, for which we thank all the participants.

BLUM,T.; CREUTZ,M.; PETRECZKY,P.

2004-02-24T23:59:59.000Z

159

Neutrinoless double beta decay and QCD corrections  

E-Print Network [OSTI]

We consider one loop QCD corrections and renormalization group running of the neutrinoless double beta decay amplitude focusing on the short-range part of the amplitude (without the light neutrino exchange) and find that these corrections can be sizeable. Depending on the operator under consideration, there can be moderate to large cancellations or significant enhancements. We discuss several specific examples in this context. Such large corrections will lead to significant shifts in the half-life estimates which currently are known to be plagued with the uncertainties due to nuclear physics inputs to the physical matrix elements.

Namit Mahajan

2014-01-30T23:59:59.000Z

160

QCD for Postgraduates (5/5)  

ScienceCinema (OSTI)

Modern QCD - Lecture 5 We will introduce and discuss in some detail the two main classes of jets: cone type and sequential-recombination type. We will discuss their basic properties, as well as more advanced concepts such as jet substructure, jet filtering, ways of optimizing the jet radius, ways of defining the areas of jets, and of establishing the quality measure of the jet-algorithm in terms of discriminating power in specific searches. Finally we will discuss applications for Higgs searches involving boosted particles.

None

2011-10-06T23:59:59.000Z

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161

Pion electric polarizability from lattice QCD  

E-Print Network [OSTI]

Electromagnetic polarizabilities are important parameters for understanding the interaction between photons and hadrons. For pions these quantities are poorly constrained experimentally since they can only be measured indirectly. New experiments at CERN and Jefferson Lab are planned that will measure the polarizabilities more precisely. Lattice QCD can be used to compute these quantities directly in terms of quark and gluons degrees of freedom, using the background field method. We present results for the electric polarizability for two different quark masses, light enough to connect to chiral perturbation theory. These are currently the lightest quark masses used in polarizability studies.

Alexandru, Andrei; Freeman, Walter; Lee, Frank

2015-01-01T23:59:59.000Z

162

Pion electric polarizability from lattice QCD  

E-Print Network [OSTI]

Electromagnetic polarizabilities are important parameters for understanding the interaction between photons and hadrons. For pions these quantities are poorly constrained experimentally since they can only be measured indirectly. New experiments at CERN and Jefferson Lab are planned that will measure the polarizabilities more precisely. Lattice QCD can be used to compute these quantities directly in terms of quark and gluons degrees of freedom, using the background field method. We present results for the electric polarizability for two different quark masses, light enough to connect to chiral perturbation theory. These are currently the lightest quark masses used in polarizability studies.

Andrei Alexandru; Michael Lujan; Walter Freeman; Frank Lee

2015-01-26T23:59:59.000Z

163

QCD on GPUs: cost effective supercomputing  

E-Print Network [OSTI]

The exponential growth of floating point power in graphics processing units (GPUs), together with their low cost, has given rise to an attractive platform upon which to deploy lattice QCD calculations. GPUs are essentially many (O(100)) core chips, that are programmed using a massively threaded environment, and so are representative of the future of high performance computing (HPC). The large ratio of raw floating point operations per second to memory bandwidth that is characteristic of GPUs necessitates that unique algorithmic design choices are made to harness their full potential. We review the progress to date in using GPUs for large scale calculations, and contrast GPUs against more traditional HPC architectures

M. A. Clark

2009-12-20T23:59:59.000Z

164

Quantum robots and quantum computers  

SciTech Connect (OSTI)

Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and systems that carry out experiments. The description of quantum computers is under active development. No description of systems to carry out experiments has been given. A small step in this direction is taken here by giving a description of quantum robots as mobile systems with on board quantum computers that interact with different environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

Benioff, P.

1998-07-01T23:59:59.000Z

165

Quantum Darwinism  

SciTech Connect (OSTI)

Quantum Darwinism - proliferation, in the environment, of multiple records of selected states of the system (its information-theoretic progeny) - explains how quantum fragility of individual state can lead to classical robustness of their multitude.

Zurek, Wojciech H [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

166

Light-Front Quantization and AdS/QCD: An Overview  

SciTech Connect (OSTI)

We give an overview of the light-front holographic approach to strongly coupled QCD, whereby a confining gauge theory, quantized on the light front, is mapped to a higher-dimensional anti de Sitter (AdS) space. The framework is guided by the AdS/CFT correspondence incorporating a gravitational background asymptotic to AdS space which encodes the salient properties of QCD, such as the ultraviolet conformal limit at the AdS boundary at z {yields} 0, as well as modifications of the geometry in the large z infrared region to describe confinement and linear Regge behavior. There are two equivalent procedures for deriving the AdS/QCD equations of motion: one can start from the Hamiltonian equation of motion in physical space time by studying the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. To a first semiclassical approximation, where quantum loops and quark masses are not included, this leads to a light-front Hamiltonian equation which describes the bound state dynamics of light hadrons in terms of an invariant impact variable {zeta} which measures the separation of the partons within the hadron at equal light-front time. Alternatively, one can start from the gravity side by studying the propagation of hadronic modes in a fixed effective gravitational background. Both approaches are equivalent in the semiclassical approximation. This allows us to identify the holographic variable z in AdS space with the impact variable {zeta}. Light-front holography thus allows a precise mapping of transition amplitudes from AdS to physical space-time. The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role.

de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC /Stanford U., Phys. Dept.

2011-08-19T23:59:59.000Z

167

AdS/QCD and Applications of Light-Front Holography  

SciTech Connect (OSTI)

Light-Front Holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space and frame-independent light-front wavefunctions of hadrons in 3 + 1 physical space-time, thus providing a compelling physical interpretation of the AdS/CFT correspondence principle and AdS/QCD, a useful framework which describes the correspondence between theories in a modified AdS5 background and confining field theories in physical space-time. To a first semiclassical approximation, where quantum loops and quark masses are not included, this approach leads to a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time. The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role. We give an overview of the light-front holographic approach to strongly coupled QCD. In particular, we study the photon-to-meson transition form factors (TFFs) F{sub M{gamma}}(Q{sup 2}) for {gamma}{gamma}* {yields} M using light-front holographic methods. The results for the TFFs for the {eta} and {eta}' mesons are also presented. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Cao, Fu-Guang; /Massey U.; de Teramond, Guy F.; /Costa Rica U.

2012-02-16T23:59:59.000Z

168

Charmed bottom baryon spectroscopy from lattice QCD  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We calculate the masses of baryons containing one, two, or three heavy quarks using lattice QCD. We consider all possible combinations of charm and bottom quarks, and compute a total of 36 different states with JP = 1/2+ and JP = 3/2+. We use domain-wall fermions for the up, down, and strange quarks, a relativistic heavy-quark action for the charm quarks, and nonrelativistic QCD for the bottom quarks. Our analysis includes results from two different lattice spacings and seven different pion masses. We perform extrapolations of the baryon masses to the continuum limit and to the physical pion mass using SU(4|2) heavy-hadron chiral perturbation theory including 1/mQ and finite-volume effects. For the 14 singly heavy baryons that have already been observed, our results agree with the experimental values within the uncertainties. We compare our predictions for the hitherto unobserved states with other lattice calculations and quark-model studies.

Brown, Zachary S; Detmold, William; Meinel, Stefan; Orginos, Kostas

2014-11-01T23:59:59.000Z

169

Non-perturbative study of QCD correlators  

E-Print Network [OSTI]

This PhD dissertation is devoted to a non-perturbative study of QCD correlators. The main tool that we use is lattice QCD. We concentrated our efforts on the study of the main correlators of the pure Yang - Mills theory in the Landau gauge, namely the ghost and the gluon propagators. We are particularly interested in determining the $\\Lqcd$ parameter. It is extracted by means of perturbative predictions available up to NNNLO. The related topic is the influence of non-perturbative effects that show up as appearance of power-corrections to the low-momentum behaviour of the Green functions. A new method of removing these power corrections allows a better estimate of $\\Lqcd$. Our result is $\\Lambda^{n_f=0}_{\\ms} = 269(5)^{+12}_{-9}$ MeV. Another question that we address is the infrared behaviour of Green functions, at momenta of order and below $\\Lqcd$. At low energy the momentum dependence of the propagators changes considerably, and this is probably related to confinement. The lattice approach allows to check the predictions of analytical methods because it gives access to non-perturbative correlators. According to our analysis the gluon propagator is finite and non-zero at vanishing momentum, and the power-law behaviour of the ghost propagator is the same as in the free case.

A. Y. Lokhov

2006-07-28T23:59:59.000Z

170

Spin-Orbit Force from Lattice QCD  

E-Print Network [OSTI]

We present a first attempt to determine nucleon-nucleon potentials in the parity-odd sector, which appear in 1P1, 3P0, 3P1, 3P2-3F2 channels, in Nf=2 lattice QCD simulations. These potentials are constructed from the Nambu-Bethe-Salpeter wave functions for J^P=0^-, 1^- and 2^-, which correspond to A1^-, T1^- and T2^- + E^- representation of the cubic group, respectively. We have found a large and attractive spin-orbit potential VLS(r) in the isospin-triplet channel, which is qualitatively consistent with the phenomenological determination from the experimental scattering phase shifts. The potentials obtained from lattice QCD are used to calculate the scattering phase shifts in 1P1, 3P0, 3P1 and 3P2-3F2 channels. The strong attractive spin-orbit force and a weak repulsive central force in spin-triplet P-wave channels lead to an attraction in the 3P2 channel, which is related to the P-wave neutron paring in neutron stars.

K. Murano; N. Ishii; S. Aoki; T. Doi; T. Hatsuda; Y. Ikeda; T. Inoue; H. Nemura; K. Sasaki

2014-06-19T23:59:59.000Z

171

Recent results on QCD thermodynamics: lattice QCD versus Hadron Resonance Gas model  

E-Print Network [OSTI]

We present our most recent investigations on the QCD cross-over transition temperatures with 2+1 staggered flavours and one-link stout improvement [JHEP 1009:073, 2010]. We extend our previous two studies [Phys. Lett. B643 (2006) 46, JHEP 0906:088 (2009)] by choosing even finer lattices ($N_t$=16) and we work again with physical quark masses. All these results are confronted with the predictions of the Hadron Resonance Gas model and Chiral Perturbation Theory for temperatures below the transition region. Our results can be reproduced by using the physical spectrum in these analytic calculations. A comparison with the results of the hotQCD collaboration is also discussed.

Szabolcs Borsanyi; Zoltan Fodor; Christian Hoelbling; Sandor D. Katz; Stefan Krieg; Claudia Ratti; Kalman K. Szabo

2010-12-23T23:59:59.000Z

172

Bound States of (Anti-)Scalar-Quarks in SU(3)c Lattice QCD  

SciTech Connect (OSTI)

Light scalar-quarks {phi} (colored scalar particles or idealized diquarks) and their color-singlet hadronic states are studied with quenched SU(3)c lattice QCD in terms of mass generation. We investigate 'scalar-quark mesons' {phi}{dagger}{phi} and 'scalar-quark baryons' {phi}{phi}{phi} as the bound states of scalar-quarks {phi}. We also investigate the bound states of scalar-quarks {phi} and quarks {psi}, i.e., {phi}{dagger}{psi}, {psi}{psi}{phi} and {phi}{phi}{psi}, which we name 'chimera hadrons'. All the new-type hadrons including {phi} are found to have a large mass due to large quantum corrections by gluons, even for zero bare scalar-quark mass m{phi} = 0 at a-1 {approx} 1GeV. We conjecture that all colored particles generally acquire a large effective mass due to dressed gluon effects.

Iida, H.; Takahashi, T. T. [Yukawa Institute for Theoretical Physics, Kyoto University, Sakyo, Kyoto 606-8502 (Japan); Suganuma, H. [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

2007-06-13T23:59:59.000Z

173

Molecular states with hidden charm and strange in QCD Sum Rules  

E-Print Network [OSTI]

This work uses the QCD Sum Rules to study the masses of the $D_s \\bar{D}_s^*$ and $D_s^* \\bar{D}_s^*$ molecular states with quantum numbers $J^{PC} = 1^{+-}$. Interpolating currents with definite C-parity are employed, and the contributions up to dimension eight in the Operator Product Expansion (OPE) are taken into account. The results indicate that two hidden strange charmonium-like states may exist in the energy ranges of $3.83 \\sim 4.13 $ GeV and $4.22 \\sim 4.54 $ GeV, respectively. The hidden strange charmonium-like states predicted in this work may be accessible in future experiments, e.g. BESIII, BelleII and SuperB. Possible decay modes, which may be useful in further research, are predicted.

Cong-Feng Qiao; Liang Tang

2014-07-08T23:59:59.000Z

174

AdS/QCD and Light Front Holography: A New Approximation to QCD  

SciTech Connect (OSTI)

The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n+L+S/2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.

Brodsky, Stanley J.; de Teramond, Guy

2010-02-15T23:59:59.000Z

175

Electroweak and QCD Results from the Tevatron  

SciTech Connect (OSTI)

The Tevatron collider has been remarkably successful and has so far delivered more than 11 fb{sup -1} of data to both the CDF and D0 experiments. Though the LHC has replaced the Tevatron as the world's most powerful collider, years of detector calibration, the huge size of the dataset and the nature of pp collisions will keep the Tevatron competitive in many selected topics in the near future. More than 10 fb{sup -1} of data has been collected by each experiment. Good understanding of the detector performance has been demonstrated by the high precision W boson mass ({Delta}M{sub W} = 31 MeV) and top quark mass ({Delta}M{sub t} = 1.06 GeV) measurements. We report the latest electroweak and QCD results from both experiments. Most analyses presented here used 4-6 fb{sup -1} of data.

Zhu, Junjie

2011-09-01T23:59:59.000Z

176

QCD thermodynamics using five-dimensional gravity  

SciTech Connect (OSTI)

We calculate the critical temperature and free energy of the gluon plasma using the dilaton potential [B. Galow, E. Megias, J. Nian, and H. J. Pirner, Nucl. Phys. B834, 330 (2010).] in the gravity theory of anti-de Sitter/QCD. The finite temperature observables are calculated in two ways: first, from the Page-Hawking computation of the free energy, and secondly using the Bekenstein-Hawking proportionality of the entropy with the area of the horizon. Renormalization is well defined, because the T=0 theory has asymptotic freedom. We further investigate the change of the critical temperature with the number of flavors induced by the change of the running coupling constant in the quenched theory. The finite temperature behavior of the speed of sound, spatial string tension and vacuum expectation value of the Polyakov loop follow from the corresponding string theory in AdS{sub 5}.

Megias, E.; Veschgini, K. [Institute for Theoretical Physics, University of Heidelberg (Germany); Pirner, H. J. [Institute for Theoretical Physics, University of Heidelberg (Germany); Max Planck Institute for Nuclear Physics, Heidelberg (Germany)

2011-03-01T23:59:59.000Z

177

Feynman rules for Coulomb gauge QCD  

SciTech Connect (OSTI)

The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel. - Highlights: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.

Andrasi, A. [Rudjer Boskovic Institute, Zagreb (Croatia)] [Rudjer Boskovic Institute, Zagreb (Croatia); Taylor, J.C., E-mail: jct@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge (United Kingdom)

2012-10-15T23:59:59.000Z

178

Subcritical String and Large N QCD  

E-Print Network [OSTI]

We pursue the possibility of using subcritical string theory in 4 space-time dimensions to establish a string dual for large N QCD. In particular we study the even G-parity sector of the 4 dimensional Neveu-Schwarz dual resonance model as the natural candidate for this string theory. Our point of view is that the open string dynamics given by this model will {\\it determine} the appropriate subcritical closed string theory, a tree level background of which should describe the sum of planar multi-loop open string diagrams. We examine the one loop open string diagram, which contains information about the closed string spectrum at weak coupling. Higher loop open string diagrams will be needed to determine closed string interactions. We also analyze the field theory limit of the one loop open string diagram and recover the correct running coupling behavior of the limiting gauge theory.

Charles B. Thorn

2010-06-29T23:59:59.000Z

179

Subcritical string and large N QCD  

SciTech Connect (OSTI)

We pursue the possibility of using subcritical string theory in 4 spacetime dimensions to establish a string dual for large N QCD. In particular we study the even G-parity sector of the 4 dimensional Neveu-Schwarz dual resonance model as the natural candidate for this string theory. Our point of view is that the open string dynamics given by this model will determine the appropriate subcritical closed string theory, a tree level background of which should describe the sum of planar multiloop open string diagrams. We examine the one-loop open string diagram, which contains information about the closed string spectrum at weak coupling. Higher loop open string diagrams will be needed to determine closed string interactions. We also analyze the field theory limit of the one-loop open string diagram and recover the correct running coupling behavior of the limiting gauge theory.

Thorn, Charles B. [Institute for Fundamental Theory, Department of Physics, University of Florida, Gainesville Florida 32611 (United States)

2008-10-15T23:59:59.000Z

180

Non-perturbative QCD amplitudes in quenched and eikonal approximations  

SciTech Connect (OSTI)

Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD. - Highlights: • We discuss the physical insight of effective locality to QCD fermionic amplitudes. • We show that an unavoidable delta function goes along with the effective locality property. • The generic structure of QCD fermion amplitudes is obtained through Random Matrix calculus.

Fried, H.M. [Physics Department, Brown University, Providence, RI 02912 (United States); Grandou, T., E-mail: Thierry.Grandou@inln.cnrs.fr [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France); Sheu, Y.-M., E-mail: ymsheu@alumni.brown.edu [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France)

2014-05-15T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Sivers and Boer-Mulders observables from lattice QCD  

E-Print Network [OSTI]

We present a first calculation of transverse momentum-dependent nucleon observables in dynamical lattice QCD employing nonlocal operators with staple-shaped, “process-dependent” Wilson lines. The use of staple-shaped Wilson ...

Musch, B. U.

182

Dual Superconductivity and Chiral Symmetry in Full QCD  

E-Print Network [OSTI]

A disorder parameter detecting dual superconductivity of the vacuum is measured across the chiral phase transition in full QCD with two flavours of dynamical staggered fermions. The observed behaviour is similar to the quenched case.

J. M. Carmona; M. D'Elia; L. Del Debbio; A. Di Giacomo; B. Lucini; G. Paffuti

2001-10-12T23:59:59.000Z

183

Global QCD Analysis and Collider Phenomenology--CTEQ  

E-Print Network [OSTI]

An overview is given of recent progress on a variety of fronts in the global QCD analysis of the parton structure of the nucleon and its implication for collider phenomenology, carried out by various subgroups of the CTEQ collaboration.

Wu-Ki Tung; H. L. Lai; J. Pumplin; P. Nadolsky; C. -P. Yuan

2007-07-02T23:59:59.000Z

184

Infrared Sensitive Physics in QCD and in Electroweak Theory  

E-Print Network [OSTI]

I recall the main ideas about the treatment of QCD infrared physics, as developed in the late seventies, and I outline some novel applications of those ideas to Electroweak Theory.

Marcello Ciafaloni

2006-12-06T23:59:59.000Z

185

QCD effects in Higgs boson production at hadron colliders  

E-Print Network [OSTI]

We present updated predictions for Higgs boson production at the Tevatron and the LHC and we review their corresponding uncertainties. We report on a study of the impact of QCD radiative corrections on the Higgs boson search at the Tevatron.

M. Grazzini

2010-01-21T23:59:59.000Z

186

Light-cone quantized QCD in 1 + 1 dimensions  

SciTech Connect (OSTI)

The QCD light-cone Hamiltonian is diagonalized in a discrete momentum-space basis. The spectra and wavefunctions for various coupling constants, numbers of color, and baryon number are computed. 20 refs., 8 figs.

Hornbostel, K.; Brodsky, S.J.; Pauli, H.C.

1988-10-01T23:59:59.000Z

187

Quantum friction  

E-Print Network [OSTI]

The Brownian motion of a light quantum particle in a heavy classical gas is theoretically described and a new expression for the friction coefficient is obtained for arbitrary temperature. At zero temperature it equals to the de Broglie momentum of the mean free path divided by the mean free path. Alternatively, the corresponding mobility of the quantum particle in the classical gas is equal to the square of the mean free path divided by the Planck constant. The Brownian motion of a quantum particle in a quantum environment is also discussed.

R. Tsekov

2012-03-12T23:59:59.000Z

188

Thermodynamics of QCD at large quark chemical potential  

E-Print Network [OSTI]

We review the existing weak-coupling results on the thermodynamic potential of deconfined QCD at small and large quark chemical potential and compare with results from lattice gauge theory as well as the exactly solvable case of large-N_f QCD. We also discuss the new analytical results on non-Fermi-liquid effects in entropy and specific heat as well as in dispersion laws of quark quasiparticles at large quark chemical potential.

Andreas Gerhold; Andreas Ipp; Anton Rebhan

2005-12-21T23:59:59.000Z

189

Monopole condensation in two-flavour Adjoint QCD  

E-Print Network [OSTI]

In QCD with adjoint fermions (aQCD) the deconfining transition takes place at a lower temperature than the chiral transition. We study the two transitions by use of the Polyakov Loop, the monopole order parameter and the chiral condensate. The deconfining transition is first order, the chiral is a crossover. The order parameters for confinement are not affected by the chiral transition. We conclude that the degrees of freedom relevant to confinement are different from those describing chiral symmetry.

G. Cossu; M. D'Elia; A. Di Giacomo; G. Lacagnina; C. Pica

2008-03-05T23:59:59.000Z

190

Model of the Stochastic Vacuum and QCD Parameters  

E-Print Network [OSTI]

Accounting for the two independent correlation functions of the QCD vacuum, we improve the simple and consistent description given by the model of the stochastic vacuum to the high-energy pp and pbar-p data, with a new determination of parameters of non-perturbative QCD. The increase of the hadronic radii with the energy accounts for the energy dependence of the observables.

Erasmo Ferreira; Flávio Pereira

1997-05-09T23:59:59.000Z

191

Gaussian quantum information  

E-Print Network [OSTI]

The science of quantum information has arisen over the last two decades centered on the manipulation of individual quanta of information, known as quantum bits or qubits. Quantum computers, quantum cryptography, and quantum ...

Weedbrook, Christian

192

Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena  

SciTech Connect (OSTI)

Light-Front Holography is one of the most remarkable features of the AdS/CFT correspondence. In spite of its present limitations it provides important physical insights into the nonperturbative regime of QCD and its transition to the perturbative domain. This novel framework allows hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The model leads to an effective confining light-front QCD Hamiltonian and a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound-state wavefunctions, and thus the fall-off as a function of the invariant mass of the constituents. The soft-wall holographic model modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics - a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryons. The model predicts a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number n. The hadron eigensolutions projected on the free Fock basis provides the complete set of valence and non-valence light-front Fock state wavefunctions {Psi}{sub n/H} (x{sub i}, k{sub {perpendicular}i}, {lambda}{sub i}) which describe the hadron's momentum and spin distributions needed to compute the direct measures of hadron structure at the quark and gluon level, such as elastic and transition form factors, distribution amplitudes, structure functions, generalized parton distributions and transverse momentum distributions. The effective confining potential also creates quark-antiquark pairs from the amplitude q {yields} q{bar q}q. Thus in holographic QCD higher Fock states can have any number of extra q{bar q} pairs. We discuss the relevance of higher Fock-states for describing the detailed structure of space and time-like form factors. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also obtained.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.

2012-02-16T23:59:59.000Z

193

In quantum gravity, summing is refining  

E-Print Network [OSTI]

In perturbative QED, the approximation is improved by summing more Feynman graphs; in non-perturbative QCD, by refining the lattice. Here we observe that in quantum gravity the two procedures may well be the same. We outline the combinatorial structure of spinfoam quantum gravity, define the continuum limit, and show that under general conditions refining foams is the same as summing over them. The conditions bear on the cylindrical consistency of the spinfoam amplitudes and on the presence of appropriate combinatorial factors, related to the implementation of diffeomorphisms invariance. Intuitively, the sites of the lattice are points of space: these are themselves quanta of the gravitational field, and thus a lattice discretization is also a Feynman history of quanta.

Carlo Rovelli; Matteo Smerlak

2011-05-03T23:59:59.000Z

194

Domain wall QCD with physical quark masses  

E-Print Network [OSTI]

We present results for several light hadronic quantities ($f_\\pi$, $f_K$, $B_K$, $m_{ud}$, $m_s$, $t_0^{1/2}$, $w_0$) obtained from simulations of 2+1 flavor domain wall lattice QCD with large physical volumes and nearly-physical pion masses at two lattice spacings. We perform a short, O(3)%, extrapolation in pion mass to the physical values by combining our new data in a simultaneous chiral/continuum `global fit' with a number of other ensembles with heavier pion masses. We use the physical values of $m_\\pi$, $m_K$ and $m_\\Omega$ to determine the two quark masses and the scale - all other quantities are outputs from our simulations. We obtain results with sub-percent statistical errors and negligible chiral and finite-volume systematics for these light hadronic quantities, including: $f_\\pi$ = 130.2(9) MeV; $f_K$ = 155.5(8) MeV; the average up/down quark mass and strange quark mass in the $\\overline {\\rm MS}$ scheme at 3 GeV, 2.997(49) and 81.64(1.17) MeV respectively; and the neutral kaon mixing parameter, $B_K$, in the RGI scheme, 0.750(15) and the $\\overline{\\rm MS}$ scheme at 3 GeV, 0.530(11).

RBC; UKQCD collaborations; :; T. Blum; P. A. Boyle; N. H. Christ; J. Frison; N. Garron; R. J. Hudspith; T. Izubuchi; T. Janowski; C. Jung; A. Juettner; C. Kelly; R. D. Kenway; C. Lehner; M. Marinkovic; R. D. Mawhinney; G. McGlynn; D. J. Murphy; S. Ohta; A. Portelli; C. T. Sachrajda; A. Soni

2014-11-25T23:59:59.000Z

195

Conformality in twelve-flavour QCD  

E-Print Network [OSTI]

The spectrum of twelve-flavor QCD has been studied in details by the LatKMI collaboration. In this proceeding we present our updated results for the spectrum obtained with the HISQ action at two lattice spacings, several volumes and fermion masses. In particular, we emphasize the existence of a flavor-singlet scalar state parametrically light with respect to the rest of the spectrum, first reported in our paper. This feature is expected to be present for theories in the conformal window, but the lattice calculation of such a state is difficult and requires noise-reduction techniques together with large statistics, in order to evaluate disconnected diagrams. Being able to provide a robust observed connection between a light flavor-singlet scalar and (near-)conformality is an important step towards observing a light composite Higgs boson in walking technicolor theories on the lattice. We also show updated results for the mass anomalous dimension $\\gamma_m$ obtained from various spectral quantities, including th...

Aoki, Yasumichi; Bennet, Ed; Kurachi, Masafumi; Maskawa, Toshihide; Miura, Kohtaroh; Nagai, Kei-ichi; Ohki, Hiroshi; Rinaldi, Enrico; Shibata, Akihiro; Yamawaki, Koichi; Yamazaki, Takeshi

2015-01-01T23:59:59.000Z

196

Conformality in twelve-flavour QCD  

E-Print Network [OSTI]

The spectrum of twelve-flavor QCD has been studied in details by the LatKMI collaboration. In this proceeding we present our updated results for the spectrum obtained with the HISQ action at two lattice spacings, several volumes and fermion masses. In particular, we emphasize the existence of a flavor-singlet scalar state parametrically light with respect to the rest of the spectrum, first reported in our paper. This feature is expected to be present for theories in the conformal window, but the lattice calculation of such a state is difficult and requires noise-reduction techniques together with large statistics, in order to evaluate disconnected diagrams. Being able to provide a robust observed connection between a light flavor-singlet scalar and (near-)conformality is an important step towards observing a light composite Higgs boson in walking technicolor theories on the lattice. We also show updated results for the mass anomalous dimension $\\gamma_m$ obtained from various spectral quantities, including the string tension, under the assumption that the theory is inside the conformal window.

Yasumichi Aoki; Tatsumi Aoyama; Ed Bennett; Masafumi Kurachi; Toshihide Maskawa; Kohtaroh Miura; Kei-ichi Nagai; Hiroshi Ohki; Enrico Rinaldi; Akihiro Shibata; Koichi Yamawaki; Takeshi Yamazaki

2015-01-29T23:59:59.000Z

197

Maximum Entropy Analysis of the Spectral Functions in Lattice QCD  

E-Print Network [OSTI]

First principle calculation of the QCD spectral functions (SPFs) based on the lattice QCD simulations is reviewed. Special emphasis is placed on the Bayesian inference theory and the Maximum Entropy Method (MEM), which is a useful tool to extract SPFs from the imaginary-time correlation functions numerically obtained by the Monte Carlo method. Three important aspects of MEM are (i) it does not require a priori assumptions or parametrizations of SPFs, (ii) for given data, a unique solution is obtained if it exists, and (iii) the statistical significance of the solution can be quantitatively analyzed. The ability of MEM is explicitly demonstrated by using mock data as well as lattice QCD data. When applied to lattice data, MEM correctly reproduces the low-energy resonances and shows the existence of high-energy continuum in hadronic correlation functions. This opens up various possibilities for studying hadronic properties in QCD beyond the conventional way of analyzing the lattice data. Future problems to be studied by MEM in lattice QCD are also summarized.

M. Asakawa; T. Hatsuda; Y. Nakahara

2001-02-26T23:59:59.000Z

198

Conditional quantum distinguishability and pure quantum communication  

E-Print Network [OSTI]

I design a simple way of distinguishing non-orthogonal quantum states with perfect reliability using only quantum control-not gates in one condition. In this way, we can implement pure quantum communication in directly sending classical information, Ekert quantum cryptography and quantum teleportation without the help of classical communications channel.

Tian-Hai Zeng

2005-09-14T23:59:59.000Z

199

Search for the pentaquark resonance signature in lattice QCD  

SciTech Connect (OSTI)

Claims concerning the possible discovery of the $\\Theta^+$ pentaquark, with minimal quark content $uudd\\bar{s}$, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various pentaquark interpolating fields in the literature and create a new candidate ideal for lattice QCD simulations. Using these interpolating fields we attempt to isolate a signal for a five-quark resonance. Calculations are performed using improved actions on a large $20^{3} \\times 40$ lattice in the quenched approximation. The standard lattice resonance signal of increasing attraction between baryon constituents for increasing quark mass is not observed for spin-1/2 pentaquark states. We conclude that evidence supporting the existence of a spin-1/2 pentaquark resonance does not exist in quenched QCD.

B. G. Lasscock; J. Hedditch; D. B. Leinweber; W. Melnitchouk; A. W. Thomas; A. G. Williams; R. D. Young; J. M. Zanotti

2005-03-01T23:59:59.000Z

200

Light-Front Holography: A First Approximation to QCD  

SciTech Connect (OSTI)

Starting from the Hamiltonian equation of motion in QCD, we identify an invariant light-front coordinate {zeta} which allows the separation of the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single variable light-front Schroedinger equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-J modes on anti-de Sitter (AdS) space. This allows us to establish formally a gauge/gravity correspondence between an effective gravity theory defined on AdS5 and light front QCD.

de Teramond, Guy F.; Brodsky, Stanley J.

2008-10-03T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Monopole condensation in two-flavour Adjoint QCD  

E-Print Network [OSTI]

Two distinct phase transitions occur at different temperatures in QCD with adjoint fermions (aQCD): deconfinement and chiral symmetry restoration. In this model, quarks do no explicitely break the center Z(3) symmetry and therefore the Polyakov loop is a good order parameter for the deconfinement transition. We study monopole condensation by inspecting the expectation value of an operator which creates a monopole. Such a quantity is expected to be an order parameter for the deconfinement transition as in the case of fundamental fermions.

G. Cossu; M. D'Elia; A. Di Giacomo; G. Lacagnina; C. Pica

2006-09-26T23:59:59.000Z

202

A Stable Magnetic Background in SU(2) QCD  

E-Print Network [OSTI]

Motivated by the instability of the Savvidy-Nielsen-Olesen (SNO) vacuum we make a systematic search for a stable magnetic background in pure SU(2) QCD. It is shown that Wu-Yang monopole-antimonopole pair is unstable under vacuum fluctuations. However, it is shown that a pair of axially symmetric monopole-antimonopole string configuration is stable, provided the distance between the two strings is small enough (less than a critical value). The existence of a stable monopole-antimonopole string background strongly supports that a magnetic condensation of monopole-antimonopole pairs can indeed generate a dynamical symmetry breaking, and thus a desired magnetic confinement of color, in QCD.

Y. M. Cho; D. G. Pak

2005-10-24T23:59:59.000Z

203

A New Fracture Function Approach to QCD Initial State Radiation  

E-Print Network [OSTI]

Ordinary fracture functions, describing hadrons production in the deep inelastic scattering target fragmentation region, are generalized to account for the production of hadrons in arbitrary number, thus offering a renewed framework for dealing with QCD initial state radiation. We also propose a new jet-like observable which measures beam remnants and low-$p_{\\perp}$ scattering fragments and derive its QCD evolution equations by using Jet Calculus. Possible implications for semi-inclusive deep inelastic scattering and hadron-hadron reactions are shortly discussed.

Federico A. Ceccopieri; Luca Trentadue

2007-05-16T23:59:59.000Z

204

Nuclear Energy Density Functionals Constrained by Low-Energy QCD  

E-Print Network [OSTI]

A microscopic framework of nuclear energy density functionals is reviewed, which establishes a direct relation between low-energy QCD and nuclear structure, synthesizing effective field theory methods and principles of density functional theory. Guided by two closely related features of QCD in the low-energy limit: a) in-medium changes of vacuum condensates, and b) spontaneous breaking of chiral symmetry; a relativistic energy density functional is developed and applied in studies of ground-state properties of spherical and deformed nuclei.

Dario Vretenar

2008-02-06T23:59:59.000Z

205

Twisted mass QCD for the pion electromagnetic form factor  

SciTech Connect (OSTI)

The pion form factor is computed using quenched twisted mass QCD and the GMRES-DR matrix inverter. The momentum averaging procedure of Frezzotti and Rossi is used to remove leading lattice spacing artifacts, and numerical results for the form factor show the expected improvement with respect to the standard Wilson action. Although some matrix inverters are known to fail when applied to twisted mass QCD, GMRES-DR is found to be a viable and powerful option. Results obtained for the pion form factor are consistent with the published results from other O(a) improved actions and are also consistent with the available experimental data.

Abdel-Rehim, Abdou M.; Lewis, Randy [Department of Physics, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada)

2005-01-01T23:59:59.000Z

206

Thermodynamics of strong interaction matter from lattice QCD and the hadron resonance gas model  

E-Print Network [OSTI]

We compare recent lattice QCD calculations of higher order cumulants of net-strangeness fluctuations with hadron resonance gas (HRG) model calculations. Up to the QCD transition temperature Tc=( 154 +/- 9) MeV we find good agreement between QCD and HRG model calculations of second and fourth order cumulants, even when subtle aspects of net-baryon number, strangeness and electric charge fluctuations are probed. In particular, the fourth order cumulants indicate that also in the strangeness sector of QCD the failure of HRG model calculations sets in quite abruptly in the vicinity of the QCD transition temperature and is apparent in most observables for T > 160 MeV.

Frithjof Karsch

2013-12-30T23:59:59.000Z

207

Quantum Biology  

E-Print Network [OSTI]

A critical assessment of the recent developments of molecular biology is presented. The thesis that they do not lead to a conceptual understanding of life and biological systems is defended. Maturana and Varela's concept of autopoiesis is briefly sketched and its logical circularity avoided by postulating the existence of underlying {\\it living processes}, entailing amplification from the microscopic to the macroscopic scale, with increasing complexity in the passage from one scale to the other. Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces, is criticized. It is suggested that the correct interpretation of quantum dispersion forces (van der Waals, hydrogen bonding, and so on) as quantum coherence effects hints at the necessity of including long-ranged forces (or mechanisms for them) in condensed matter theories of biological processes. Some quantum effects in biology are reviewed and quantum mechanics is acknowledged as conceptually important to biology since without it most (if not all) of the biological structures and signalling processes would not even exist. Moreover, it is suggested that long-range quantum coherent dynamics, including electron polarization, may be invoked to explain signal amplification process in biological systems in general.

Alessandro Sergi

2009-07-11T23:59:59.000Z

208

QCD sum-rule results for heavy-light meson decay constants and comparison with lattice QCD  

E-Print Network [OSTI]

Updated predictions for the decay constants of the D, Ds, B and Bs mesons obtained from Borel QCD sum rules for heavy-light currents are presented and compared with the recent lattice averages performed by the Flavor Lattice Averaging Group. An excellent agreement is obtained in the charm sector, while some tension is observed in the bottom sector. Moreover, available lattice and QCD sum-rule calculations of the decay constants of the vector D*, Ds*, B* and Bs* mesons are compared. Again some tension in the bottom sector is observed.

W. Lucha; D. Melikhov; S. Simula

2014-11-14T23:59:59.000Z

209

QCD sum-rule results for heavy-light meson decay constants and comparison with lattice QCD  

E-Print Network [OSTI]

Updated predictions for the decay constants of the D, Ds, B and Bs mesons obtained from Borel QCD sum rules for heavy-light currents are presented and compared with the recent lattice averages performed by the Flavor Lattice Averaging Group. An excellent agreement is obtained in the charm sector, while some tension is observed in the bottom sector. Moreover, available lattice and QCD sum-rule calculations of the decay constants of the vector D*, Ds*, B* and Bs* mesons are compared. Again some tension in the bottom sector is observed.

Lucha, W; Simula, S

2014-01-01T23:59:59.000Z

210

Quark-gluon plasma phenomenology from anisotropic lattice QCD  

E-Print Network [OSTI]

The FASTSUM collaboration has been carrying out simulations of N_f=2+1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics.

Jon-Ivar Skullerud; Gert Aarts; Chris Allton; Alessandro Amato; Yannis Burnier; P. Wynne M. Evans; Pietro Giudice; Simon Hands; Tim Harris; Aoife Kelly; Seyong Kim; Maria Paola Lombardo; Mehmet B. Oktay; Alexander Rothkopf; Sinéad M. Ryan

2014-12-30T23:59:59.000Z

211

INT Summer School Proposal Lattice QCD for Nuclear Physics  

E-Print Network [OSTI]

INT Summer School Proposal Lattice QCD for Nuclear Physics Organizers Huey-Wen Lin Department of Nuclear Physics, Johann-Joachim-Becher-Weg 45 55099 Mainz, Germany meyerh@kph.uni-mainz.de David Richards techniques to the study of nuclear physics. The goal of this summer school is to educate and prepare the next

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

212

Singlet Free Energies and Renormalized Polyakov Loop in full QCD  

E-Print Network [OSTI]

We calculate the free energy of a static quark anti-quark pair and the renormalized Polyakov loop in 2+1- and 3- flavor QCD using $16^3 \\times 4$ and $16^3 \\times 6$ lattices and improved staggered p4 action. We also compare the renormalized Polyakov loop with the results of our earlier studies.

K. Petrov

2006-10-05T23:59:59.000Z

213

Matching NLO QCD computations with PYTHIA using MC@NLO  

E-Print Network [OSTI]

We present the matching between a next-to-leading order computation in QCD and the PYTHIA parton shower Monte Carlo, according to the MC@NLO formalism. We study the case of initial-state radiation, and consider in particular single vector boson hadroproduction.

Paolo Torrielli; Stefano Frixione

2010-05-05T23:59:59.000Z

214

Quark number susceptibility of high temperature and finite density QCD  

E-Print Network [OSTI]

We utilize lattice simulations of the dimensionally reduced effective field theory (EQCD) to determine the quark number susceptibility of QCD at high temperature ($T>2T_c$). We also use analytic continuation to obtain results at finite density. The results extrapolate well from known perturbative expansion (accurate in extremely high temperatures) to 4d lower temperature lattice data

Ari Hietanen; Kari Rummukainen

2007-10-26T23:59:59.000Z

215

Quark-gluon plasma phenomenology from anisotropic lattice QCD  

E-Print Network [OSTI]

The FASTSUM collaboration has been carrying out simulations of N_f=2+1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics.

Skullerud, Jon-Ivar; Allton, Chris; Amato, Alessandro; Burnier, Yannis; Evans, P Wynne M; Giudice, Pietro; Hands, Simon; Harris, Tim; Kelly, Aoife; Kim, Seyong; Lombardo, Maria Paola; Oktay, Mehmet B; Rothkopf, Alexander; Ryan, Sinéad M

2015-01-01T23:59:59.000Z

216

The QCD string spectrum and conformal field theory  

SciTech Connect (OSTI)

The low energy excitation spectrum of the critical Wilson surface is discussed between the roughening transition and the continuum limit of lattice QCD. The fine structure of the spectrum is interpreted within the framework of two-dimensional conformal field theory.

Keisuke Jimmy Juge; Julius Kuti; Colin Morningstar

2002-12-19T23:59:59.000Z

217

Study of Bc->KK decay with perturbative QCD approach  

E-Print Network [OSTI]

In the framework of the perturbative QCD approach, we study the charmless pure weak annihilation Bc->KK decay and find that the branching ratio BR(Bc->KK) O(10^-7). This prediction is so tiny that the Bc->KK decay might be unmeasurable at the Large Hadron Collider.

Yue-Ling Yang; Jun-Feng Sun; Na Wang

2010-04-16T23:59:59.000Z

218

Optimization of Lattice QCD codes for the AMD Opteron processor  

E-Print Network [OSTI]

We report our experience of the optimization of the lattice QCD codes for the new Opteron cluster at DESY Hamburg, including benchmarks. Details of the optimization using SSE/SSE2 instructions and the effective use of prefetch instructions are discussed.

Miho Koma

2005-10-05T23:59:59.000Z

219

Polyakov loop, Hadron Resonance Gas Model and Thermodynamics of QCD  

E-Print Network [OSTI]

We summarize recent results on the hadron resonance gas description of QCD. In particular, we apply this approach to describe the equation of state and the vacuum expectation value of the Polyakov loop in several representations. Ambiguities related to exactly which states should be included are discussed.

E. Megias; E. Ruiz Arriola; L. L. Salcedo

2013-10-11T23:59:59.000Z

220

On-Shell Unitarity Bootstrap for QCD Amplitudes  

E-Print Network [OSTI]

We describe the recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD. The method combines the unitarity method with loop-level on-shell recursion. The unitarity method is used to compute cut-containing parts of amplitudes, and on-shell recursion is used for the remaining rational terms.

Carola F. Berger; Zvi Bern; Lance J. Dixon; Darren Forde; David A. Kosower

2006-10-16T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Small Quarkonium states in an anisotropic QCD plasma  

E-Print Network [OSTI]

We determine the hard-loop resummed propagator in an anisotropic QCD plasma in general covariant gauges and define a potential between heavy quarks from the Fourier transform of its static limit. We find that the potential exhibits angular dependence and that binding of very small quarkonium states is stronger than in an isotropic plasma.

Yun Guo

2008-05-16T23:59:59.000Z

222

Quantum Cavitation  

E-Print Network [OSTI]

We consider the theoretical setting of a superfluid like 3He in a rotating container, which is set between the two layers of a type-II superconductor. We describe the superfluid vortices as a 2-dimensional Ising-like model on a triangular lattice in presence of local magnetic fields. The interaction term of the superfluid vortices with the Abrikosov vortices of the superconductor appears then as a symmetry breaking term in the free energy. Such a term gives a higher probability of quantum tunnelling across the potential barrier for bubbles nucleation, thus favouring quantum cavitation.

Paola Zizzi; Eliano Pessa; Fabio Cardone

2010-06-05T23:59:59.000Z

223

General Algorithm For Improved Lattice Actions on Parallel Computing Architectures  

E-Print Network [OSTI]

Quantum field theories underlie all of our understanding of the fundamental forces of nature. The are relatively few first principles approaches to the study of quantum field theories [such as quantum chromodynamics (QCD) relevant to the strong interaction] away from the perturbative (i.e., weak-coupling) regime. Currently the most common method is the use of Monte Carlo methods on a hypercubic space-time lattice. These methods consume enormous computing power for large lattices and it is essential that increasingly efficient algorithms be developed to perform standard tasks in these lattice calculations. Here we present a general algorithm for QCD that allows one to put any planar improved gluonic lattice action onto a parallel computing architecture. High performance masks for specific actions (including non-planar actions) are also presented. These algorithms have been successfully employed by us in a variety of lattice QCD calculations using improved lattice actions on a 128 node Thinking Machines CM-5. {\\underline{Keywords}}: quantum field theory; quantum chromodynamics; improved actions; parallel computing algorithms.

F. D. R. Bonnet; Derek B. Leinweber; Anthony G. Williams

2001-02-09T23:59:59.000Z

224

Quantum++ - A C++11 quantum computing library  

E-Print Network [OSTI]

Quantum++ is a general-purpose multi-threaded quantum computing library written in C++11 and composed solely of header files. The library is not restricted to qubit systems or specific quantum information processing tasks, being capable of simulating arbitrary quantum processes. The main design factors taken in consideration were ease of use, portability, and performance.

Vlad Gheorghiu

2014-12-15T23:59:59.000Z

225

Quantum arithmetic with the Quantum Fourier Transform  

E-Print Network [OSTI]

The Quantum Fourier Transform offers an interesting way to perform arithmetic operations on a quantum computer. We review existing Quantum Fourier Transform adders and multipliers and propose some modifications that extend their capabilities. Among the new circuits, we propose a quantum method to compute the weighted average of a series of inputs in the transform domain.

Lidia Ruiz-Perez; Juan Carlos Garcia-Escartin

2014-11-21T23:59:59.000Z

226

Quantum Geometry and Quantum Gravity  

E-Print Network [OSTI]

The purpose of this contribution is to give an introduction to quantum geometry and loop quantum gravity for a wide audience of both physicists and mathematicians. From a physical point of view the emphasis will be on conceptual issues concerning the relationship of the formalism with other more traditional approaches inspired in the treatment of the fundamental interactions in the standard model. Mathematically I will pay special attention to functional analytic issues, the construction of the relevant Hilbert spaces and the definition and properties of geometric operators: areas and volumes.

J. Fernando Barbero G.

2008-04-23T23:59:59.000Z

227

Quantum Error Correction for Quantum Memories  

E-Print Network [OSTI]

Active quantum error correction using qubit stabilizer codes has emerged as a promising, but experimentally challenging, engineering program for building a universal quantum computer. In this review we consider the formalism of qubit stabilizer and subsystem stabilizer codes and their possible use in protecting quantum information in a quantum memory. We review the theory of fault-tolerance and quantum error-correction, discuss examples of various codes and code constructions, the general quantum error correction conditions, the noise threshold, the special role played by Clifford gates and the route towards fault-tolerant universal quantum computation. The second part of the review is focused on providing an overview of quantum error correction using two-dimensional (topological) codes, in particular the surface code architecture. We discuss the complexity of decoding and the notion of passive or self-correcting quantum memories. The review does not focus on a particular technology but discusses topics that will be relevant for various quantum technologies.

Barbara M. Terhal

2015-01-20T23:59:59.000Z

228

Quantum Heat Engines Using Superconducting Quantum Circuits  

E-Print Network [OSTI]

We propose a quantum analog of the internal combustion engine used in most cars. Specifically, we study how to implement the Otto-type quantum heat engine (QHE) with the assistance of a Maxwell's demon. Three steps are required: thermalization, quantum measurement, and quantum feedback controlled by the Maxwell demon. We derive the positive-work condition of this composite QHE. Our QHE can be constructed using superconducting quantum circuits. We explicitly demonstrate the essential role of the demon in this macroscopic QHE.

H. T. Quan; Y. D. Wang; Yu-xi Liu; C. P. Sun; Franco Nori

2006-09-14T23:59:59.000Z

229

Higher Moments of Net-Baryon Distribution as Probes of QCD Critical Point  

E-Print Network [OSTI]

It is crucially important to find an observable which is independent on the acceptance and late collision process, in order to search for the possible Critical Point predicted by QCD. By utilizing A Multi-Phase Transport (AMPT) model and Ultra Relativistic Quantum Molecular Dynamics (UrQMD) model, we study the centrality and evolution time dependence of higher moments of net-baryon distribution in Au + Au collisions at $\\sqrt{s_{NN}}=17.3$ GeV. The results suggest that Kurtosis and Skewness are less sensitive to the acceptance effect and late collision process. Thus, they should be good observables providing the information of the early stage of heavy ion collision. In addition, our study shows that the Kurtosis times $\\sigma^{2}$ of net-proton distribution are quite different to that of net-baryon when collisions energy is lower than $\\sqrt{s_{NN}}$ = 20 GeV, the Monte Calor calculations on Kurtosis$\\cdot\\sigma^{2}$ have a deviation from the theoretical predictions.

Y. Zhou; S. S. Shi; K. Xiao; K. J. Wu; F. Liu

2010-04-15T23:59:59.000Z

230

Quantum nonlocality  

SciTech Connect (OSTI)

It is argued that the validity of the predictions of quantum theory in certain spin-correlation experiments entails a violation of Einstein's locality idea that no causal influence can act outside the forward light cone. First, two preliminary arguments suggesting such a violation are reviewed. They both depend, in intermediate stages, on the idea that the results of certain unperformed experiments are physically determinate. The second argument is entangled also with the problem of the meaning of physical reality. A new argument having neither of these characteristics is constructed. It is based strictly on the orthodox ideas of Bohr and Heisenberg, and has no realistic elements, or other ingredients, that are alien to orthodox quantum thinking.

Stapp, H.P.

1988-04-01T23:59:59.000Z

231

Quantum Information Science | ornl.gov  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Geographic Information Science and Technology Quantum Information Science Quantum Communication and Security Quantum-Enhanced Sensing Quantum Computing Supercomputing and...

232

Quantum Thermometry  

E-Print Network [OSTI]

In this review article we revisit and spell out the details of previous work on how Berry phase can be used to construct a precision quantum thermometer. An important advantage of such a scheme is that there is no need for the thermometer to acquire thermal equilibrium with the sample. This reduces measurement times and avoids precision limitations. We also review how such methods can be used to detect the Unruh effect.

Robert B. Mann; Eduardo Martin-Martinez

2014-05-22T23:59:59.000Z

233

More on the renormalization group limit cycle in QCD  

SciTech Connect (OSTI)

We present a detailed study of the recently conjectured infrared renormalization group limit cycle in QCD using chiral effective field theory. We show that small increases in the up and down quark masses, corresponding to a pion mass around 200 MeV, can move QCD to the critical renormalization group trajectory for an infrared limit cycle in the three-nucleon system. At the critical values of the quark masses, the binding energies of the deuteron and its spin-singlet partner are tuned to zero and the triton has infinitely many excited states with an accumulation point at the three-nucleon threshold. At next-to-leading order in the chiral counting, we find three parameter sets where this effect occurs. For one of them, we study the structure of the three-nucleon system using both chiral and contact effective field theories in detail. Furthermore, we calculate the influence of the limit cycle on scattering observables.

Evgeny Epelbaum; Hans-Werner Hammer; Ulf-G. Meissner; Andreas Nogga

2006-02-26T23:59:59.000Z

234

Gauge Configurations for Lattice QCD from The Gauge Connection  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

The Gauge Connection is an experimental archive for lattice QCD and a repository of gauge configurations made freely available to the community. Contributors to the archive include the Columbia QCDSP collaboration, the MILC collaboration, and others. Configurations are stored in QCD archive format, consisting of an ASCII header which defines various parameters, followed by binary data. NERSC has also provided some utilities and examples that will aid users in handling the data. Users may browse the archive, but are required to register for a password in order to download data. Contents of the archive are organized under four broad headings: Quenched (more than 1200 configurations); Dynamical, Zero Temperature (more than 300 configurations); MILC Improved Staggered Asqtad Lattices (more than 7000 configurations); and Dynamical, Finite Temperature (more than 1200 configurations)

235

Heavy hybrid mesons in the QCD sum rule  

E-Print Network [OSTI]

We study the spectra of the hybrid mesons containing one heavy quark ($q\\bar{Q}g$) within the framework of QCD sum rules in the heavy quark limit. The derived sum rules are stable with the variation of the Borel parameter within their corresponding working ranges. The extracted binding energy for the heavy hybrid doublets $H(S)$ and $M(T)$ is almost degenerate. We also calculate the pionic couplings between these heavy hybrid and the conventional heavy meson doublets using the light-cone QCD sum rule method. The extracted coupling constants are rather small as a whole. With these couplings we make a rough estimate of the partial widths of these pionic decay channels.

Peng-Zhi Huang; Shi-Lin Zhu

2011-03-03T23:59:59.000Z

236

Analytic Perturbation Theory Model for QCD and Upsilon Decay  

E-Print Network [OSTI]

An elegant and more precise formula for the 3-loop perturbative QCD coupling is discussed. It improves the common expression (e.g., canonized by PDG) in few GeV region. On its base, we propose simple analytic Model for ghost-free QCD running couplings and their effective powers within the Analytic Perturbation Theory, in both the space-like (Euclidean) and time-like (Minkowskian) regions, very accurate in the range above 1 GeV. Effectiveness of the new Model is illustrated by the example of Upsilon(1S) decay where the standard analysis gives $\\alpha_s(M_{\\Ups})=0.170\\pm 0.004$ value that is inconsistent with the bulk of data. Instead, we obtain $\\alpha_s(M_{\\Ups})=0.185\\pm 0.005$ that corresponds to $\\alpha_s(M_Z)=0.120\\pm 0.002 $ that is close to the world average.

Shirkov, D V

2006-01-01T23:59:59.000Z

237

Quantum Locality?  

SciTech Connect (OSTI)

Robert Griffiths has recently addressed, within the framework of a ‘consistent quantum theory’ (CQT) that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues, on the basis of his examination of certain arguments that claim to demonstrate the existence of such nonlocal influences, that such influences do not exist. However, his examination was restricted mainly to hidden-variable-based arguments that include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by attributing to the system properties alien to that system. Hence Griffiths’ rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his ‘consistent quantum theory’ shows that the cited proof is valid within that restrictive framework. This necessary existence, within the ‘consistent’ framework, of long range essentially instantaneous influences refutes the claim made by Griffiths that his ‘consistent’ framework is superior to the orthodox quantum theory of von Neumann because it does not entail instantaneous influences. An added section responds to Griffiths’ reply, which cites a litany of ambiguities that seem to restrict, devastatingly, the scope of his CQT formalism, apparently to buttress his claim that my use of that formalism to validate the nonlocality theorem is flawed. But the vagaries that he cites do not upset the proof in question. It is show here in detail why the precise statement of this theorem justifies the specified application of CQT. It is also shown, in response to his challenge, why a putative proof of locality that he has proposed is not valid.

Stapp, Henry

2011-11-10T23:59:59.000Z

238

Transverse momentum dependent quark densities from Lattice QCD  

SciTech Connect (OSTI)

We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simpli?ed operator geometry show visible dipole de- formations of spin-dependent quark momentum densities. We discuss the basic concepts of the method, including renormalization of the gauge link, and an ex- tension to a more elaborate operator geometry that would allow us to analyze process-dependent TMDs such as the Sivers-function.

Bernhard Musch,Philipp Hagler,John Negele,Andreas Schafer

2011-02-01T23:59:59.000Z

239

Transverse momentum distributions inside the nucleon from Lattice QCD  

SciTech Connect (OSTI)

We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities. We discuss the basic concepts of the method, including renormalization of the gauge link, and an extension to a more elaborate operator geometry that would allow us to analyze process-dependent TMDs such as the Sivers-function.

Bernhard Musch, Philipp Hagler, John Negele, Andreas Schafer

2010-06-01T23:59:59.000Z

240

QCD Thermodynamics with an almost realistic quark mass spectrum  

E-Print Network [OSTI]

We will report on the status of a new large scale calculation of thermodynamic quantities in QCD with light up and down quarks corresponding to an almost physical light quark mass value and a heavier strange quark mass. These calculations are currently being performed on the QCDOC Teraflops computers at BNL. We will present new lattice calculations of the transition temperature and various susceptibilities reflecting properties of the chiral transition. All these quantities are of immediate interest for heavy ion phenomenology.

C. Schmidt

2006-01-25T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

The Additional Interpolators Method for Variational Analysis in Lattice QCD  

E-Print Network [OSTI]

In this paper, I describe the Additional Interpolators Method, a new technique for variational analysis in lattice QCD. It is shown to be an excellent method which uses additional interpolators to remove backward in time running states that would otherwise contaminate the signal. The proof of principle, which also makes use of the Time-Shift Trick (Generalized Pencil-of-Functions method), will be delivered at an example on a $64^4$ lattice close to the physical pion mass.

Rainer W. Schiel

2015-03-09T23:59:59.000Z

242

Two-Color QCD with Chiral Chemical Potential  

E-Print Network [OSTI]

The phase diagram of two-color QCD with a chiral chemical potential is studied on the lattice. The focus is on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulations are carried out with dynamical staggered fermions without rooting. The dependence of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented.

V. V. Braguta; V. A. Goy; E. -M. Ilgenfritz; A. Yu. Kotov; A. V. Molochkov; M. Muller-Preussker; B. Petersson; A. Schreiber

2014-11-19T23:59:59.000Z

243

QCD Jet Rates with the Inclusive Generalized kt Algorithms  

E-Print Network [OSTI]

We derive generating functions, valid to next-to-double logarithmic accuracy, for QCD jet rates according to the inclusive forms of the kt, Cambridge/Aachen and anti-kt algorithms, which are equivalent at this level of accuracy. We compare the analytical results with jet rates and average jet multiplicities from the SHERPA event generator, and study the transition between Poisson-like and staircase-like behaviour of jet ratios.

Erik Gerwick; Ben Gripaios; Steffen Schumann; Bryan Webber

2013-04-15T23:59:59.000Z

244

Light-Front Holography and Non-Perturbative QCD  

SciTech Connect (OSTI)

The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n + L + S = 2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.

Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

2009-12-09T23:59:59.000Z

245

A QCD Sum Rules Approach to Mixing of Hadrons  

SciTech Connect (OSTI)

A method for the calculation of the hadronic mixing angles using QCD sum rules is proposed. This method is then applied to predict the mixing angle between the heavy cascade hyperons {Xi}{sub Q} and {Xi}{sub Q}{sup '} where Q = c or Q = b. It is obtained the {theta}{sub b} = 6.4 deg. {+-}1.8 deg. and {theta}{sub c} = 5.5 deg. {+-}1.8 deg.

Aliev, T. M. [Physics Department, Middle East Technical University, Ankara (Turkey); Permanent institute: Institute of Physics, Baku (Azerbaijan); Ozpineci, A. [Physics Department, Middle East Technical University, Ankara (Turkey); Zamiralov, V. S. [Institute of Nuclear Physics, M. V. Lomonosov MSU, Moscow (Russian Federation)

2010-12-28T23:59:59.000Z

246

Spectrum of quenched twisted mass lattice QCD at maximal twist  

SciTech Connect (OSTI)

Hadron masses are computed from quenched twisted mass lattice QCD for a degenerate doublet of up and down quarks with the twist angle set to {pi}/2, since this maximally-twisted theory is expected to be free of linear discretization errors. Two separate definitions of the twist angle are used, and the hadron masses for these two cases are compared. The flavor breaking, that can arise due to twisting, is discussed in the context of mass splittings within the {delta}(1232) multiplet.

Abdel-Rehim, Abdou M.; Lewis, Randy; Woloshyn, R.M. [Department of Physics, University of Regina, Regina, SK, S4S 0A2 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada)

2005-05-01T23:59:59.000Z

247

Quantum Learning Machine  

E-Print Network [OSTI]

We propose a novel notion of a quantum learning machine for automatically controlling quantum coherence and for developing quantum algorithms. A quantum learning machine can be trained to learn a certain task with no a priori knowledge on its algorithm. As an example, it is demonstrated that the quantum learning machine learns Deutsch's task and finds itself a quantum algorithm, that is different from but equivalent to the original one.

Jeongho Bang; James Lim; M. S. Kim; Jinhyoung Lee

2008-03-20T23:59:59.000Z

248

QCD and QED dynamics in the EMC effect  

E-Print Network [OSTI]

Applying exact QCD sum rules for the baryon charge and energy momentum conservation we demonstrate that if the only degrees of freedom in nuclei were nucleons, nuclear pdfs would be the additive sum of the nucleon pdfs at the same Bjorken x=AQ^2/2(p_A q) 0.1. Hence QCD implies that the proper quantity to reveal violation of the additivity due to presence of nonnucleonic degrees of freedom in nuclei is the ratio R_A(x,Q)=(2/A)F_{2A}(x,Q)/F_{2D}(x,Q). Use of variable x_p=Q^2/2q_0m_p in the experimental studies instead of x leads to the deviation of R_A(x_p,Q) from one even if the nucleus would consist only of nucleons with small momenta.Implementation of QCD dynamics and contribution of equivalent photons accounts for at least a half of the deviation of R_A(x_p,Q) from one for x0.6 posing a serious challenge for most of the proposed models of the EMC effect. The data are consistent with a scenario in which the hadronic EMC effect reflects suppression of rare quark-gluon configurations in nucleons belonging to S...

Frankfurt, Leonid

2012-01-01T23:59:59.000Z

249

Elementary quantum cloning machines  

E-Print Network [OSTI]

The task of reception of a copy of an arbitrary quantum state with use of a minimum quantity of quantum operations is considered.

V. N. Dumachev

2006-02-03T23:59:59.000Z

250

Resonant conversions of QCD axions into hidden axions and suppressed isocurvature perturbations  

E-Print Network [OSTI]

We study in detail MSW-like resonant conversions of QCD axions into hidden axions, including cases where the adiabaticity condition is only marginally satisfied, and where anharmonic effects are non-negligible. When the resonant conversion is efficient, the QCD axion abundance is suppressed by the hidden and QCD axion mass ratio. We find that, when the resonant conversion is incomplete due to a weak violation of the adiabaticity, the CDM isocurvature perturbations can be significantly suppressed, while non-Gaussianity of the isocurvature perturbations generically remain unsuppressed. The isocurvature bounds on the inflation scale can therefore be relaxed by the partial resonant conversion of the QCD axions into hidden axions.

Naoya Kitajima; Fuminobu Takahashi

2014-11-17T23:59:59.000Z

251

E-Print Network 3.0 - anisotropic lattice qcd Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Department of Applied Science Collection: Environmental Sciences and Ecology 72 Romanian Reports in Physics, Vol. 58, No. 1, P. 1317, 2006 PHASES OF QCD: LATTICE...

252

E-Print Network 3.0 - anisotropic qcd plasma Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Group - Neutron Beta Decay Time Reversal Invariance Test Collection: Physics 53 Romanian Reports in Physics, Vol. 58, No. 1, P. 1317, 2006 PHASES OF QCD: LATTICE...

253

Perturbative QCD, a universal QCD scale, long-range spin-orbit potential, and the properties of heavy quarkonia  

SciTech Connect (OSTI)

A modified version of Richardson's potential is used to calculate the energies, fine-structure splittings, leptonic widths, and dipole transition rates of charmonium and the {Upsilon} system. The effects of the perturbative color-magnetic (spin-dependent) potentials are included to the full radiative one-loop level. The question of the consistency of the data with a universal QCD scale and its expression in the central and spin-dependent potentials is addressed.

Fulcher, L.P. (Department of Physics and Astronomy, Bowling Green State University, Bowling Green, Ohio (USA))

1991-10-01T23:59:59.000Z

254

Quantum coherence and correlations in quantum system  

E-Print Network [OSTI]

Criteria of measure quantifying quantum coherence, a unique property of quantum system, are proposed recently. In this paper, we firstly give an uncertainty-like expression relating the coherence and the entropy of quantum system. Then, we obtain three trade-offs among the coherence, the discord and the deficit in the bipartite quantum system.As a consequence, we obtain that the relative entropy of coherence satisfies the super-additivity. Finally, we discuss the relations between the entanglement and the coherence.

Zhengjun Xi; Yongming Li; Heng Fan

2014-12-24T23:59:59.000Z

255

Ground State Quantum Computation  

E-Print Network [OSTI]

We formulate a novel ground state quantum computation approach that requires no unitary evolution of qubits in time: the qubits are fixed in stationary states of the Hamiltonian. This formulation supplies a completely time-independent approach to realizing quantum computers. We give a concrete suggestion for a ground state quantum computer involving linked quantum dots.

Ari Mizel; M. W. Mitchell; Marvin L. Cohen

1999-08-11T23:59:59.000Z

256

Localized quantum walks as secured quantum memory  

E-Print Network [OSTI]

We show that a quantum walk process can be used to construct and secure quantum memory. More precisely, we show that a localized quantum walk with temporal disorder can be engineered to store the information of a single, unknown qubit on a compact position space and faithfully recover it on demand. Since the localization occurss with a finite spread in position space, the stored information of the qubit will be naturally secured from the simple eavesdropper. Our protocol can be adopted to any quantum system for which experimental control over quantum walk dynamics can be achieved.

C. M. Chandrashekar; Th. Busch

2015-04-21T23:59:59.000Z

257

Hybrid quantum devices and quantum engineering  

E-Print Network [OSTI]

We discuss prospects of building hybrid quantum devices involving elements of atomic and molecular physics, quantum optics and solid state elements with the attempt to combine advantages of the respective systems in compatible experimental setups. In particular, we summarize our recent work on quantum hybrid devices and briefly discuss recent ideas for quantum networks. These include interfacing of molecular quantum memory with circuit QED, and using nanomechanical elements strongly coupled to qubits represented by electronic spins, as well as single atoms or atomic ensembles.

Margareta Wallquist; Klemens Hammerer; Peter Rabl; Mikhail Lukin; Peter Zoller

2009-11-19T23:59:59.000Z

258

Nuclear Theory Group, University of Washington recent and planned research. [Annual report, April 1992--April 1993  

SciTech Connect (OSTI)

The work of the five staff members is presented individually in turn. (1) Nonperturbative aspects of quantum chromodynamics and its implication for phenomena involving nucleon structure, nuclear structure, and relativistic heavy-ion collisions. (2) Symmetries and the connection of the quark-gluon description of nucleons and nuclei with the nucleon-meson degrees of freedom-parity nonconservation, time reversal invariance, chiral symmetry and charge symmetry, QCD sum rules. (3) The relation between nuclear physics and quantum chromodynamics-physics of color transparency, fundamental symmetries, physics of confinement and hadronic form factors, EMC effect. (4) Chirally invariant chromo-dielectric soliton model, many-nucleon system in models of QCD, flux tube dynamics, {anti p}-p to {anti {Lambda}}-{Lambda} and {anti {Lambda}}-{Sigma} collisions, isotopic effects in atomic parity nonconservation, quantum molecular dynamics. (5) Numerical work related to lattice QCD simulations, and analytical work related to model studies of hadronic phenomenology and the development and understanding of new methods.

Not Available

1993-11-01T23:59:59.000Z

259

Hybrid Quantum Cloning Machine  

E-Print Network [OSTI]

In this work, we introduce a special kind of quantum cloning machine called Hybrid quantum cloning machine. The introduced Hybrid quantum cloning machine or transformation is nothing but a combination of pre-existing quantum cloning transformations. In this sense it creates its own identity in the field of quantum cloners. Hybrid quantum cloning machine can be of two types: (i) State dependent and (ii) State independent or Universal. We study here the above two types of Hybrid quantum cloning machines. Later we will show that the state dependent hybrid quantum-cloning machine can be applied on only four input states. We will also find in this paper another asymmetric universal quantum cloning machine constructed from the combination of optimal universal B-H quantum cloning machine and universal anti-cloning machine. The fidelities of the two outputs are different and their values lie in the neighborhood of ${5/6} $

Satyabrata Adhikari; A. K. Pati; Indranil Chakrabarty; B. S. Choudhury

2007-05-04T23:59:59.000Z

260

Quantum optical waveform conversion  

E-Print Network [OSTI]

Currently proposed architectures for long-distance quantum communication rely on networks of quantum processors connected by optical communications channels [1,2]. The key resource for such networks is the entanglement of matter-based quantum systems with quantum optical fields for information transmission. The optical interaction bandwidth of these material systems is a tiny fraction of that available for optical communication, and the temporal shape of the quantum optical output pulse is often poorly suited for long-distance transmission. Here we demonstrate that nonlinear mixing of a quantum light pulse with a spectrally tailored classical field can compress the quantum pulse by more than a factor of 100 and flexibly reshape its temporal waveform, while preserving all quantum properties, including entanglement. Waveform conversion can be used with heralded arrays of quantum light emitters to enable quantum communication at the full data rate of optical telecommunications.

D Kielpinski; JF Corney; HM Wiseman

2010-10-11T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Quantum Ice : a quantum Monte Carlo study  

E-Print Network [OSTI]

Ice states, in which frustrated interactions lead to a macroscopic ground-state degeneracy, occur in water ice, in problems of frustrated charge order on the pyrochlore lattice, and in the family of rare-earth magnets collectively known as spin ice. Of particular interest at the moment are "quantum spin ice" materials, where large quantum fluctuations may permit tunnelling between a macroscopic number of different classical ground states. Here we use zero-temperature quantum Monte Carlo simulations to show how such tunnelling can lift the degeneracy of a spin or charge ice, stabilising a unique "quantum ice" ground state --- a quantum liquid with excitations described by the Maxwell action of 3+1-dimensional quantum electrodynamics. We further identify a competing ordered "squiggle" state, and show how both squiggle and quantum ice states might be distinguished in neutron scattering experiments on a spin ice material.

Nic Shannon; Olga Sikora; Frank Pollmann; Karlo Penc; Peter Fulde

2011-12-13T23:59:59.000Z

262

Quantum Thermodynamic Cycles and quantum heat engines  

E-Print Network [OSTI]

In order to describe quantum heat engines, here we systematically study isothermal and isochoric processes for quantum thermodynamic cycles. Based on these results the quantum versions of both the Carnot heat engine and the Otto heat engine are defined without ambiguities. We also study the properties of quantum Carnot and Otto heat engines in comparison with their classical counterparts. Relations and mappings between these two quantum heat engines are also investigated by considering their respective quantum thermodynamic processes. In addition, we discuss the role of Maxwell's demon in quantum thermodynamic cycles. We find that there is no violation of the second law, even in the existence of such a demon, when the demon is included correctly as part of the working substance of the heat engine.

H. T. Quan; Yu-xi Liu; C. P. Sun; Franco Nori

2007-04-03T23:59:59.000Z

263

Quantum Bootstrapping via Compressed Quantum Hamiltonian Learning  

E-Print Network [OSTI]

Recent work has shown that quantum simulation is a valuable tool for learning empirical models for quantum systems. We build upon these results by showing that a small quantum simulators can be used to characterize and learn control models for larger devices for wide classes of physically realistic Hamiltonians. This leads to a new application for small quantum computers: characterizing and controlling larger quantum computers. Our protocol achieves this by using Bayesian inference in concert with Lieb-Robinson bounds and interactive quantum learning methods to achieve compressed simulations for characterization. Whereas Fisher information analysis shows that current methods which employ short-time evolution are suboptimal, interactive quantum learning allows us to overcome this limitation. We illustrate the efficiency of our bootstrapping protocol by showing numerically that an 8-qubit Ising model simulator can be used to calibrate and control a 50 qubit Ising simulator while using only about 750 kilobits of experimental data.

Nathan Wiebe; Christopher Granade; David G. Cory

2015-03-30T23:59:59.000Z

264

Four-point vector correlators and AdS/QCD correspondence  

E-Print Network [OSTI]

We derive the four-point vector correlators in QCD from AdS/QCD correspondence. It is shown that meson poles are correctly reproduced. The final expression also suggests a nonzero amplitude in the limit of zero virtuality of two longitudinal gluons. This fact does not mean that one can produce, absorb or scatter real longitudinal gluons.

Konyushikhin, Maxim

2009-01-01T23:59:59.000Z

265

Extremal quantum protocols  

E-Print Network [OSTI]

Generalized quantum instruments correspond to measurements where the input and output are either states or more generally quantum circuits. These measurements describe any quantum protocol including games, communications, and algorithms. The set of generalized quantum instruments with a given input and output structure is a convex set. Here we investigate the extremal points of this set for the case of finite dimensional quantum systems and generalized instruments with finitely many outcomes. We derive algebraic necessary and sufficient conditions for extremality.

Giacomo Mauro D'Ariano; Paolo Perinotti; Michal Sedlak

2011-01-25T23:59:59.000Z

266

A Framework for Lattice QCD Calculations on GPUs  

E-Print Network [OSTI]

Computing platforms equipped with accelerators like GPUs have proven to provide great computational power. However, exploiting such platforms for existing scientific applications is not a trivial task. Current GPU programming frameworks such as CUDA C/C++ require low-level programming from the developer in order to achieve high performance code. As a result porting of applications to GPUs is typically limited to time-dominant algorithms and routines, leaving the remainder not accelerated which can open a serious Amdahl's law issue. The lattice QCD application Chroma allows to explore a different porting strategy. The layered structure of the software architecture logically separates the data-parallel from the application layer. The QCD Data-Parallel software layer provides data types and expressions with stencil-like operations suitable for lattice field theory and Chroma implements algorithms in terms of this high-level interface. Thus by porting the low-level layer one can effectively move the whole application in one swing to a different platform. The QDP-JIT/PTX library, the reimplementation of the low-level layer, provides a framework for lattice QCD calculations for the CUDA architecture. The complete software interface is supported and thus applications can be run unaltered on GPU-based parallel computers. This reimplementation was possible due to the availability of a JIT compiler (part of the NVIDIA Linux kernel driver) which translates an assembly-like language (PTX) to GPU code. The expression template technique is used to build PTX code generators and a software cache manages the GPU memory. This reimplementation allows us to deploy an efficient implementation of the full gauge-generation program with dynamical fermions on large-scale GPU-based machines such as Titan and Blue Waters which accelerates the algorithm by more than an order of magnitude.

F. T. Winter; M. A. Clark; R. G. Edwards; B. Joó

2014-08-25T23:59:59.000Z

267

TMD Parton Distribution and Fragmentation Functions with QCD Evolution  

E-Print Network [OSTI]

We assess the current phenomenological status of transverse momentum dependent (TMD) parton distribution functions (PDFs) and fragmentation functions (FFs) and study the effect of consistently including perturbative QCD (pQCD) evolution. Our goal is to initiate the process of establishing reliable, QCD-evolved parametrizations for the TMD PDFs and TMD FFs that can be used both to test TMD-factorization and to search for evidence of the breakdown of TMD-factorization that is expected for certain processes. In this article, we focus on spin-independent processes because they provide the simplest illustration of the basic steps and can already be used in direct tests of TMD-factorization. Our calculations are based on the Collins-Soper-Sterman (CSS) formalism, supplemented by recent theoretical developments which have clarified the precise definitions of the TMD PDFs and TMD FFs needed for a valid TMD-factorization theorem. Starting with these definitions, we numerically generate evolved TMD PDFs and TMD FFs using as input existing parametrizations for the collinear PDFs, collinear FFs, non-perturbative factors in the CSS factorization formalism, and recent fixed-scale fits. We confirm that evolution has important consequences, both qualitatively and quantitatively, and argue that it should be included in future phenomenological studies of TMD functions. Our analysis is also suggestive of extensions to processes that involve spin-dependent functions such as the Boer-Mulders, Sivers, or Collins functions, which we intend to pursue in future publications. At our website we have made available the tables and calculations needed to obtain the TMD parametrizations presented herein.

S. Mert Aybat; Ted C. Rogers

2011-06-15T23:59:59.000Z

268

A Framework for Lattice QCD Calculations on GPUs  

SciTech Connect (OSTI)

Computing platforms equipped with accelerators like GPUs have proven to provide great computational power. However, exploiting such platforms for existing scientific applications is not a trivial task. Current GPU programming frameworks such as CUDA C/C++ require low-level programming from the developer in order to achieve high performance code. As a result porting of applications to GPUs is typically limited to time-dominant algorithms and routines, leaving the remainder not accelerated which can open a serious Amdahl's law issue. The lattice QCD application Chroma allows to explore a different porting strategy. The layered structure of the software architecture logically separates the data-parallel from the application layer. The QCD Data-Parallel software layer provides data types and expressions with stencil-like operations suitable for lattice field theory and Chroma implements algorithms in terms of this high-level interface. Thus by porting the low-level layer one can effectively move the whole application in one swing to a different platform. The QDP-JIT/PTX library, the reimplementation of the low-level layer, provides a framework for lattice QCD calculations for the CUDA architecture. The complete software interface is supported and thus applications can be run unaltered on GPU-based parallel computers. This reimplementation was possible due to the availability of a JIT compiler (part of the NVIDIA Linux kernel driver) which translates an assembly-like language (PTX) to GPU code. The expression template technique is used to build PTX code generators and a software cache manages the GPU memory. This reimplementation allows us to deploy an efficient implementation of the full gauge-generation program with dynamical fermions on large-scale GPU-based machines such as Titan and Blue Waters which accelerates the algorithm by more than an order of magnitude.

Winter, Frank; Clark, M.A.; Edwards, Robert G.; Joo, Balint

2014-08-01T23:59:59.000Z

269

Quantum loop programs  

E-Print Network [OSTI]

Loop is a powerful program construct in classical computation, but its power is still not exploited fully in quantum computation. The exploitation of such power definitely requires a deep understanding of the mechanism of quantum loop programs. In this paper, we introduce a general scheme of quantum loops and describe its computational process. The notions of termination and almost termination are proposed for quantum loops, and the function computed by a quantum loop is defined. To show their expressive power, quantum loops are applied in describing quantum walks. Necessary and sufficient conditions for termination and almost termination of a general quantum loop on any mixed input state are presented. A quantum loop is said to be (almost) terminating if it (almost) terminates on any input state. We show that a quantum loop is almost terminating if and only if it is uniformly almost terminating. It is observed that a small disturbance either on the unitary transformation in the loop body or on the measurement in the loop guard can make any quantum loop (almost) terminating. Moreover, a representation of the function computed by a quantum loop is given in terms of finite summations of matrices. To illustrate the notions and results obtained in this paper, two simplest classes of quantum loop programs, one qubit quantum loops, and two qubit quantum loops defined by controlled gates, are carefully examined.

Mingsheng Ying; Yuan Feng

2007-01-04T23:59:59.000Z

270

Dynamical model for longitudinal wave functions in light-front holographic QCD  

SciTech Connect (OSTI)

We construct a Schrödinger-like equation for the longitudinal wave function of a meson in the valence qq{sup -bar} sector, based on the ’t Hooft model for large-N two-dimensional QCD, and combine this with the usual transverse equation from light-front holographic QCD, to obtain a model for mesons with massive quarks. The computed wave functions are compared with the wave function ansatz of Brodsky and de Téramond and used to compute decay constants and parton distribution functions. The basis functions used to solve the longitudinal equation may be useful for more general calculations of meson states in QCD. -- Highlights: •Provide relativistic quark model based on light-front holographic QCD. •Incorporate dependence on quark mass. •Consistent with the Brodsky–de Téramond quark-wave-function ansatz. •Compute meson decay constants and parton distribution functions. •Illustrate use of basis functions that could be convenient for more general numerical calculations in light-front QCD.

Chabysheva, Sophia S.; Hiller, John R., E-mail: jhiller@d.umn.edu

2013-10-15T23:59:59.000Z

271

Spectroscopy of triply charmed baryons from lattice QCD  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

The spectrum of excitations of triply-charmed baryons is computed using lattice QCD including dynamical light quark fields. The spectrum obtained has baryonic states with well-defined total spin up to 7/2 and the low-lying states closely resemble the expectation from models with an SU(6)x O(3) symmetry. Energy splittings between extracted states, including those due to spin-orbit coupling in the heavy quark limit are computed and compared against data at other quark masses.

Padmanath, M; Edwards, Robert G; Mathur, Nilmani; Peardon, Michael

2014-10-01T23:59:59.000Z

272

The K+ K+ scattering length from Lattice QCD  

SciTech Connect (OSTI)

The K+K+ scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the MILC asqtad-improved gauge configurations with fourth-rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation theory at next-to-leading order, which includes the leading effects of the finite lattice spacing, is used to extrapolate the results of the lattice calculation to the physical value of mK + /fK + . We find mK^+ aK^+ K^+ = â~0.352 ± 0.016, where the statistical and systematic errors have been combined in quadrature.

Silas Beane; Thomas Luu; Konstantinos Orginos; Assumpta Parreno; Martin Savage; Aaron Torok; Andre Walker-Loud

2007-09-11T23:59:59.000Z

273

Elliptic flow from pQCD + saturation + hydro model  

E-Print Network [OSTI]

We have previously predicted multiplicities and transverse momentum spectra of hadrons for the most central LHC Pb+Pb collisions at $\\sqrt{s_{NN}}=5.5$ TeV using initial state for hydrodynamic evolution from pQCD + final state saturation model. By considering binary collision and wounded nucleon profiles we extend these studies to non-central collisions, and predict the $p_{T}$ dependence of minimum bias $v_{2}$ for pions at the LHC. For protons we also show how the $p_{T}$ dependence of $v_2$ changes from RHIC to the LHC.

K. J. Eskola; H. Niemi; P. V. Ruuskanen

2007-05-15T23:59:59.000Z

274

Viscous Quark-Gluon Plasma Model Through Fluid QCD Approach  

E-Print Network [OSTI]

A Lagrangian density for viscous quark-gluon plasma has been constructed within the fluid-like QCD framework. Gauge symmetry is preserved for all terms inside the Lagrangian, except for the viscous term. The transition mechanism from point particle field to fluid field, and vice versa, is discussed. The energy momentum tensor that is relevant for the gluonic plasma having the nature of fluid bulk of gluon sea is derived within the model. By imposing conservation law in the energy momentum tensor, shear viscosity appears as extractable from the equation.

T. P. Djun; B. Soegijono; T. Mart; L. T. Handoko

2014-10-14T23:59:59.000Z

275

PLQCD library for Lattice QCD on multi-core machines  

E-Print Network [OSTI]

PLQCD is a stand-alone software library developed under PRACE for lattice QCD. It provides an implementation of the Dirac operator for Wilson type fermions and few efficient linear solvers. The library is optimized for multi-core machines using a hybrid parallelization with OpenMP+MPI. The main objectives of the library is to provide a scalable implementation of the Dirac operator for efficient computation of the quark propagator. In this contribution, a description of the PLQCD library is given together with some benchmark results.

A. Abdel-Rehim; C. Alexandrou; N. Anastopoulos; G. Koutsou; I. Liabotis; N. Papadopoulou

2014-05-04T23:59:59.000Z

276

Infrared exponents of gluon and ghost propagators from Lattice QCD  

E-Print Network [OSTI]

The compatibility of the pure power law infrared solution of QCD Dyson-Schwinger equations (DSE) and lattice data for the gluon and ghost propagators in Landau gauge is discussed. For the gluon propagator, the lattice data is compatible with the DSE infrared solution with an exponent $\\kappa\\sim0.53$, measured using a technique that suppresses finite volume effects and allows to model these corrections to the lattice data. For the ghost propagator, the lattice data does not seem to follow the infrared DSE power law solution.

O. Oliveira; P. J. Silva

2007-10-02T23:59:59.000Z

277

An estimate for the location of QCD critical end point  

E-Print Network [OSTI]

It is proposed that a study of the ratio of shear viscosity to entropy density $\\frac{\\eta}{s}$ as a function of the baryon chemical potential $\\mu_B$, and temperature T, provides a dynamic probe for the critical end point (CEP) in hot and dense QCD matter. An initial estimate from an elliptic flow excitation function gives $\\mu^{\\text{cep}}_B \\sim 150-180$ MeV and $T_{\\text{cep}} \\sim 165 - 170$ MeV for the location of the the CEP. These values place the CEP in the range for "immediate" validation at RHIC.

Roy A. Lacey; N. N. Ajitanand; J. M. Alexander; P. Chung; J. Jia; A. Taranenko; P. Danielewicz

2007-08-27T23:59:59.000Z

278

An estimate for the location of QCD critical end point  

E-Print Network [OSTI]

It is proposed that a study of the ratio of shear viscosity to entropy density $\\frac{\\eta}{s}$ as a function of the baryon chemical potential $\\mu_B$, and temperature T, provides a dynamic probe for the critical end point (CEP) in hot and dense QCD matter. An initial estimate from an elliptic flow excitation function gives $\\mu^c_B \\sim 150-180$ MeV and $T_c \\sim 165$ MeV for the location of the the CEP. These values place the CEP in the range for "immediate" observation at RHIC.

Lacey, Roy A; Alexander, J M; Chung, P; Jia, J; Taranenko, A; Danielewicz, P

2007-01-01T23:59:59.000Z

279

Flavor singlet physics in lattice QCD with background fields  

SciTech Connect (OSTI)

We show that hadronic matrix elements can be extracted from lattice simulations with background fields that arise from operator exponentiation. Importantly, flavor-singlet matrix elements can be evaluated without requiring the computation of disconnected diagrams, thus facilitating a calculation of the quark contribution to the spin of the proton and the singlet axial coupling, g{sub A}{sup 0}. In the two-nucleon sector, a background field approach will allow calculation of the magnetic and quadrupole moments of the deuteron and an investigation of the EMC effect directly from lattice QCD. Matrix elements between states of differing momenta are also analyzed in the presence of background fields.

Detmold, W. [Department of Physics, University of Washington, Box 351560, Seattle, Washington 98195 (United States)

2005-03-01T23:59:59.000Z

280

QCD plasma instability and thermalisation at heavy ion collisions  

E-Print Network [OSTI]

Under suitable non-equilibrium conditions QCD plasma can develop plasma instabilities, where some modes of the plasma grow exponentially. It has been argued that these instabilities can play a significant role in the thermalisation of the plasma in heavy-ion collision experiments. We study the instability in SU(2) plasmas using the hard thermal loop effective lattice theory, which is suitable for studying real-time evolution of long wavelength modes in the plasma. We observe that under suitable conditions the plasma can indeed develop an instability which can grow to a very large magnitude, necessary for the rapid thermalisation in heavy-ion collisions.

Dietrich Bodeker; Kari Rummukainen

2007-11-13T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Excited nucleon spectrum from lattice QCD with maximum entropy method  

E-Print Network [OSTI]

We study excited states of the nucleon in quenched lattice QCD with the spectral analysis using the maximum entropy method. Our simulations are performed on three lattice sizes $16^3\\times 32$, $24^3\\times 32$ and $32^3\\times 32$, at $\\beta=6.0$ to address the finite volume issue. We find a significant finite volume effect on the mass of the Roper resonance for light quark masses. After removing this systematic error, its mass becomes considerably reduced toward the direction to solve the level order puzzle between the Roper resonance $N'(1440)$ and the negative-parity nucleon $N^*(1535)$.

K. Sasaki; S. Sasaki; T. Hatsuda; M. Asakawa

2003-09-29T23:59:59.000Z

282

Evolved QCD predictions for the meson-photon transition form factors: beyond the semiclassical AdS/QCD approximation  

SciTech Connect (OSTI)

The QCD evolution of the pion distribution amplitude (DA) {phi}{sub {pi}} (x, Q{sup 2}) is computed for several commonly used models. Our analysis includes the nonperturbative form predicted by lightfront holographic QCD, thus combining the nonperturbative bound state dynamics of the pion with the perturbative ERBL evolution of the pion distribution amplitude. We calculate the meson-photon transition form factors for the {pi}{sup 0}, {eta} and {eta}' using the hard-scattering formalism. We point out that a widely-used approximation of replacing {phi} (x; (1 - x)Q) with {phi} (x;Q) in the calculations will unjustifiably reduce the predictions for the meson-photon transition form factors. It is found that the four models of the pion DA discussed give very different predictions for the Q{sup 2} dependence of the meson-photon transition form factors in the region of Q{sup 2} > 30 GeV{sup 2}. More accurate measurements of these transition form factors at the large Q{sup 2} region will be able to distinguish the four models of the pion DA. The rapid growth of the large Q{sup 2} data for the pion-photon transition form factor reported by the BABAR Collaboration is difficult to explain within the current framework of QCD. If the BABAR data for the meson-photon transition form factor for the {pi}{sup 0} is confirmed, it could indicate physics beyond-the-standard model, such as a weakly-coupled elementary C = + axial vector or pseudoscalar z{sup 0} in the few GeV domain, an elementary field which would provide the coupling {gamma}{sup *}{gamma} {yields} z{sup 0} {yields} {pi}{sup 0} at leading twist. Our analysis thus indicates the importance of additional measurements of the pion-photon transition form factor at large Q{sup 2}.

Brodsky, Stanley J.; /SLAC; Cao, Fu-Guang; /Massey U. /Beijing Normal U.; de Teramond, Guy F.; /Costa Rica U.

2011-11-04T23:59:59.000Z

283

The Forbidden Quantum Adder  

E-Print Network [OSTI]

Addition plays a central role in mathematics and physics, while adders are ubiquitous devices in computation and electronics. In this sense, usual sum operations can be realized by classical Turing machines and also, with a suitable algorithm, by quantum Turing machines. Moreover, the sum of state vectors in the same Hilbert space, known as quantum superposition, is at the core of quantum physics. In fact, entanglement and the promised exponential speed-up of quantum computing are based on such superpositions. Here, we consider the existence of a quantum adder, defined as a unitary operation mapping two unknown quantum states encoded in different quantum systems onto their sum codified in a single one. The surprising answer is that this quantum adder is forbidden and it has the quantum cloning machine as a special case. This no-go result is of fundamental nature and its deep implications should be further studied.

U. Alvarez-Rodriguez; M. Sanz; L. Lamata; E. Solano

2014-11-14T23:59:59.000Z

284

Scalar-Quark Systems and Chimera Hadrons in SU(3)_c Lattice QCD  

E-Print Network [OSTI]

Light scalar-quarks \\phi (colored scalar particles or idealized diquarks) and their color-singlet hadronic states are studied with quenched SU(3)_c lattice QCD in terms of mass generation in strong interaction without chiral symmetry breaking. We investigate ``scalar-quark mesons'' \\phi^\\dagger \\phi and ``scalar-quark baryons'' \\phi\\phi\\phi which are the bound states of scalar-quarks \\phi. We also investigate the bound states of scalar-quarks \\phi and quarks \\psi, i.e., \\phi^\\dagger \\psi, \\psi\\psi\\phi and \\phi\\phi\\psi, which we name ``chimera hadrons''. All the new-type hadrons including \\phi are found to have a large mass even for zero bare scalar-quark mass m_\\phi=0 at a^{-1}\\simeq 1GeV. We find that the constituent scalar-quark and quark picture is satisfied for all the new-type hadrons. Namely, the mass of the new-type hadron composed of m \\phi's and n \\psi's, M_{{m}\\phi+{n}\\psi}, satisfies M_{{m}\\phi+{n}\\psi}\\simeq {m} M_\\phi +{n} M_\\psi, where M_\\phi and M_\\psi are the constituent scalar-quark and quark mass, respectively. M_\\phi at m_\\phi=0 estimated from these new-type hadrons is 1.5-1.6GeV, which is larger than that of light quarks, M_\\psi\\simeq 400{\\rm MeV}. Therefore, in the systems of scalar-quark hadrons and chimera hadrons, scalar-quarks acquire large mass due to large quantum corrections by gluons. Together with other evidences of mass generations of glueballs and charmonia, we conjecture that all colored particles generally acquire a large effective mass due to dressed gluon effects.

H. Iida; H. Suganuma; T. T. Takahashi

2007-05-28T23:59:59.000Z

285

Stochastic propagators for multi-pion correlation functions in lattice QCD with GPUs  

E-Print Network [OSTI]

Motivated by the application of L\\"uscher's finite volume method to the study of the lightest scalar resonance in the $\\pi\\pi \\to \\pi\\pi$ isoscalar channel, in this article we describe our studies of multi-pion correlation functions computed using stochastic propagators in quenched lattice QCD, harnessing GPUs for acceleration. We consider two methods for constructing the correlation functions. One "outer product" approach becomes quite expensive at large lattice extent $L$, having an ${\\cal O}(L^7)$ scaling. The other "stochastic operator" approach scales as ${\\cal O}(N_r^2 L^4)$, where $N_r$ is the number of random sources. It would become more efficient if variance reduction techniques are used and the volume is fairly large. It is also found that correlations between stochastic propagators appearing in the same diagram, when a single set of random source vectors is used, lead to much larger errors than if separate random sources are used for each propagator. The calculations involve states with quantum numbers of the vacuum, so all-to-all propagators must be computed. For this reason, GPUs are ideally suited to accelerating the calculation. For this work we have integrated the Columbia Physics System (CPS) and QUDA GPU inversion library, in the case of clover fermions. Finally, we show that the completely quark disconnected diagram is crucial to the results, and that neglecting it would lead to answers which are far from the true value for the effective mass in this channel. This is unfortunate, because as we also show, this diagram has very large errors, and in fact dominates the error budget.

Joel Giedt; Dean Howarth

2014-08-11T23:59:59.000Z

286

Proposal for feasible experiments of cold-atom quantum simulator of U(1) lattice gauge-Higgs model  

E-Print Network [OSTI]

Lattice gauge theory has provided us with a crucial non-perturbative method in studying canonical models in high-energy physics such as quantum chromodynamics. Among other models of lattice gauge theory, the lattice gauge-Higgs model is a quite important one because it describes wide variety of phenomena/models related to the Anderson-Higgs mechanism such as superconductivity, the standard model of particle physics, and inflation process of the early universe. In this paper, to realize a quantum simulator of the U(1) lattice gauge-Higgs model on an optical lattice filled by cold atoms, we propose two feasible methods: (i) Wannier states in the excited bands and (ii) dipolar atoms in a multilayer optical lattice. We pay attentions to respect the constraint of Gauss's law and avoid nonlocal gauge interactions. Numerical simulations of the time development of an electric flux by using the Gross-Pitaevskii equations reveal some interesting characteristics of dynamical aspect of the model.

Yoshihito Kuno; Kenichi Kasamatsu; Yoshiro Takahashi; Ikuo Ichinose; Tetsuo Matsui

2014-12-24T23:59:59.000Z

287

WIMP Dark Matter and the QCD Equation of State  

E-Print Network [OSTI]

Weakly Interacting Massive Particles (WIMPs) of mass m freeze out at a temperature T_f ~ m/25, i.e. in the range 400 MeV -- 40 GeV for a particle in the typical mass range 10 -- 1000 GeV. The WIMP relic density, which depends on the effective number of relativistic degrees of freedom at T_f, may be measured to better than 1% by Planck, warranting comparable theoretical precision. Recent theoretical and experimental advances in the understanding of high temperature QCD show that the quark gluon plasma departs significantly from ideal behaviour up to temperatures of several GeV, necessitating an improvement of the cosmological equation of state over those currently used. We discuss how this increases the relic density by approximately 1.5 -- 3.5% in benchmark mSUGRA models, with an uncertainly in the QCD corrections of 0.5 -- 1 %. We point out what further work is required to achieve a theoretical accuracy comparable with the expected observational precision, and speculate that the effective number of degrees of freedom at T_f may become measurable in the foreseeable future.

Mark Hindmarsh; Owe Philipsen

2005-01-25T23:59:59.000Z

288

QCD phase diagram at finite baryon and isospin chemical potentials  

SciTech Connect (OSTI)

The phase structure of two-flavor QCD is explored for thermal systems with finite baryon- and isospin-chemical potentials, {mu}{sub B} and {mu}{sub iso}, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. The PNJL model with the scalar-type eight-quark interaction can reproduce lattice QCD data at not only {mu}{sub iso}={mu}{sub B}=0, but also {mu}{sub iso}>0 and {mu}{sub B}=0. In the {mu}{sub iso}-{mu}{sub B}-T space, where T is temperature, the critical endpoint of the chiral phase transition in the {mu}{sub B}-T plane at {mu}{sub iso}=0 moves to the tricritical point of the pion-superfluidity phase transition in the {mu}{sub iso}-T plane at {mu}{sub B}=0 as {mu}{sub iso} increases. The thermodynamics at small T is controlled by {radical}({sigma}{sup 2}+{pi}{sup 2}) defined by the chiral and pion condensates, {sigma} and {pi}.

Sasaki, Takahiro; Sakai, Yuji; Yahiro, Masanobu [Department of Physics, Graduate School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Kouno, Hiroaki [Department of Physics, Saga University, Saga 840-8502 (Japan)

2010-12-01T23:59:59.000Z

289

Impact of Dynamical Fermions on QCD Vacuum Structure  

E-Print Network [OSTI]

We examine how dynamical fermions affect both the UV and infrared structure of the QCD vacuum. We consider large $28^3 \\times 96$ lattices from the MILC collaboration, using a gluonic definition of the topological charge density, founded on a new over-improved stout-link smearing algorithm. The algorithm reproduces established results from the overlap formalism and is designed to preserve nontrivial topological objects including instantons. At short distances we focus on the topological charge correlator, $$, where negative values at small $x$ reveal a sign-alternating layered structure to the topological-charge density of the QCD vacuum. We find that the magnitudes of the negative dip in the $$ correlator and the positive $$ contact term are both increased with the introduction of dynamical fermion degrees of freedom. This is in accord with expectations based on charge renormalization and the vanishing of the topological susceptibility in the chiral limit. At large distances we examine the extent to which instanton-like objects are found on the lattice, and how their distributions vary between quenched and dynamical gauge fields. We show that dynamical gauge fields contain more instanton-like objects with an average size greater than in the quenched vacuum. Finally, we directly visualize the topological charge density in order to investigate the effects of dynamical sea-quark degrees of freedom on topology.

Peter J. Moran; Derek B. Leinweber

2008-01-14T23:59:59.000Z

290

QCD sum rules on the complex Borel plane  

E-Print Network [OSTI]

Borel transformed QCD sum rules conventionally use a real valued parameter (the Borel mass) for specifying the exponential weight over which hadronic spectral functions are averaged. In this paper, it is shown that the Borel mass can be generalized to have complex values and that new classes of sum rules can be derived from the resulting averages over the spectral functions. The real and imaginary parts of these novel sum rules turn out to have damped oscillating kernels and potentially contain a larger amount of information on the hadronic spectrum than the real valued QCD sum rules. As a first practical test, we have formulated the complex Borel sum rules for the phi meson channel and have analyzed them using the maximum entropy method, by which we can extract the most probable spectral function from the sum rules without strong assumptions on its functional form. As a result, it is demonstrated that, compared to earlier studies, the complex valued sum rules allow us to extract the spectral function with a significantly improved resolution and thus to study more detailed structures of the hadronic spectrum than previously possible.

Ken-Ji Araki; Keisuke Ohtani; Philipp Gubler; Makoto Oka

2014-03-25T23:59:59.000Z

291

Equation of state and QCD transition at finite temperature  

SciTech Connect (OSTI)

We calculate the equation of state in 2+1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent N{sub {tau}} = 8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 actions. Overall, we find good agreement between results obtained with these two O(a{sup 2}) improved staggered fermion discretization schemes. A comparison with earlier calculations on coarser lattices is performed to quantify systematic errors in current studies of the equation of state. We also present results for observables that are sensitive to deconfining and chiral aspects of the QCD transition on N{sub {tau}} = 6 and 8 lattices. We find that deconfinement and chiral symmetry restoration happen in the same narrow temperature interval. In an Appendix we present a simple parametrization of the equation of state that can easily be used in hydrodynamic model calculations. In this parametrization we also incorporated an estimate of current uncertainties in the lattice calculations which arise from cutoff and quark mass effects. We estimate these systematic effects to be about 10 MeV.

Bazavov, A; Bhattacharya, T; Cheng, M; Christ, N H; DeTar, C; Ejiri, S; Gottlieb, S; Gupta, R; Heller, U M; Huebner, K; Jung, C; Karsch, F; Laermann, E; Levkova, L; Miao, C; Mawhinney, R D; Petreczky, P; Schmidt, C; Soltz, R A; Soeldner, W; Sugar, R; Toussaint, D; Vranas, P

2009-03-25T23:59:59.000Z

292

Quantum chimera states  

E-Print Network [OSTI]

We study a theoretical model of closed quasi-hermitian chain of spins which exhibits quantum analogues of chimera states, i.e. long life classical states for which a part of an oscillator chain presents an ordered dynamics whereas another part presents a disordered chaotic dynamics. For the quantum analogue, the chimera behavior deals with the entanglement between the spins of the chain. We discuss the entanglement properties, quantum chaos, quantum disorder and semi-classical similarity of our quantum chimera system. The quantum chimera concept is novel and induces new perspectives concerning the entanglement of multipartite systems.

David Viennot; Lucile Aubourg

2014-11-19T23:59:59.000Z

293

Efficient Quantum Filtering for Quantum Feedback Control  

E-Print Network [OSTI]

We discuss an efficient numerical scheme for the recursive filtering of diffusive quantum stochastic master equations. We show that the resultant quantum trajectory is robust and may be used for feedback based on inefficient measurements. The proposed numerical scheme is amenable to approximation, which can be used to further reduce the computational burden associated with calculating quantum trajectories and may allow real-time quantum filtering. We provide a two-qubit example where feedback control of entanglement may be within the scope of current experimental systems.

Pierre Rouchon; Jason F. Ralph

2015-01-06T23:59:59.000Z

294

Feasible quantum engineering of quantum multiphoton superpositions  

E-Print Network [OSTI]

We examine an experimental setup implementing a family of quantum non-Gaussian filters. The filters can be applied to an arbitrary two-mode input state. We assume realistic photodetection in the filtering process and explore two different models of inefficient detection: a beam splitter of a small reflectivity located in front of a perfect detector and a Weierstrass transform applied to the unperturbed measurement outcomes. We explicitly give an operator which describes the coherent action of the filters in the realistic experimental conditions. The filtered states may find applications in quantum metrology, quantum communication and other quantum tasks.

Magdalena Stobi?ska

2014-09-03T23:59:59.000Z

295

An Upgrade Proposal from the PHENIX Collaboration  

E-Print Network [OSTI]

In this document the PHENIX collaboration proposes a major upgrade to the PHENIX detector at the Relativistic Heavy Ion Collider. This upgrade, sPHENIX, enables an extremely rich jet and beauty quarkonia physics program addressing fundamental questions about the nature of the strongly coupled quark-gluon plasma (QGP), discovered experimentally at RHIC to be a perfect fluid. The startling dynamics of the QGP on fluid-like length scales is an emergent property of quantum chromodynamics (QCD), seemingly implicit in the Lagrangian but stubbornly hidden from view. QCD is an asymptotically free theory, but how QCD manifests as a strongly coupled fluid with specific shear viscosity near $T_C$, as low as allowed by the uncertainty principle, is as fundamental an issue as that of how confinement itself arises.

Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Akimoto, R; Alexander, J; Aoki, K; Apadula, N; Asano, H; Atomssa, E T; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Bai, X; Bandara, N; Bannier, B; Barish, K N; Baron, O; Bassalleck, B; Bathe, S; Baublis, V; Baumgart, S; Bazilevsky, A; Beaumier, M; Beckman, S; Belmont, R; Benjamin, G; Berdnikov, A; Berdnikov, Y; Blackburn, J; Blau, D S; Bobrek, M; Bok, J; Boose, S; Boyle, K; Britton,, C L; Brooks, M L; Bryslawskyj, J; Bumazhnov, V; Butler, C; Butsyk, S; Campbell, S; Carollo, A; Chai, J -S; Chen, C -H; Chernichenko, S; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choi, S; Chollet, S; Christiansen, P; Chujo, T; Cianciolo, V; Citron, Z; Cole, B A; Cronin, N; Crossett, N; Csanád, M; D'Orazio, L; Dairaku, S; Danley, D; Datta, A; Daugherity, M S; David, G; DeBlasio, K; Debraine, A; Dehmelt, K; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Ding, L; Dion, A; Diss, P B; Do, J H; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Eberle, L; Efremenko, Y V; Engelmore, T; Enokizono, A; Esumi, S; Eyser, K O; Fadem, B; Feege, N; Fields, D E; Finger, M; FingerJr., M; Fleuret, F; Fokin, S L; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fusayasu, T; Gainey, K; Gal, C; Gallus, P; Garg, P; Garishvili, A; Garishvili, I; Gastaldi, F; Ge, H; Giannotti, P; Giordarno, F; Glenn, A; Gong, X; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Perdekamp, M Grosse; Gu, Y; Gunji, T; Guragain, H; Hachiya, T; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamilton, H F; Han, S Y; Hanks, J; Hasegawa, S; Haseler, T O S; Hashimoto, K; Hayano, R; Hayashi, S; He, X; Hemmick, T K; Hester, T; Hill, J C; Hoefferkamp, M; Hollis, R S; Homma, K; Hong, B; Hori, Y; Hoshino, T; Huang, J; Huang, S; Hutchins, J R; Ichihara, T; Ikeda, Y; Imai, K; Imazu, Y; Imrek, J; Inaba, M; Iordanova, A; Isenhower, D; Isinhue, A; Isupov, A; Ivanischev, D; Ivanov, V; Jacak, B V; Jeon, S J; Jezghani, M; Jia, J; Jiang, X; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kamin, J; Kanda, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kawall, D; Kazantsev, A V; Kehayias, H -J; Key, J A; Khachatryan, V; Khandai, P K; Khanzadeev, A; Kijima, K M; Kim, C; Kim, D H; Kim, D J; Kim, E -J; Kim, H J; Kim, K -B; Kim, M; Kim, Y -J; Kim, Y K; Kimelman, B; Kiss, Á; Kistenev, E; Kitamura, R; Klatsky, J; Kleinjan, D; Kline, P; Koblesky, T; Kochenda, L; Kofarago, M; Komatsu, Y; Komkov, B; Koster, J; Kotchetkov, D; Kotov, D; Kravtsov, P; Krizek, F; Kurita, K; Kuriyama, M; Kurosawa, M; Kwon, Y; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, G H; Lee, J; Lee, K B; Lee, K S; Lee, S; Lee, S H; Lefferts, R; Leitch, M J; Leite, M A L; Leitgab, M; Lewis, B; Li, X; Lim, S H; Lipski, A; Litvinenko, A; Liu, M X; Love, B; Lynch, D; Lynch, M; Maguire, C F; Makdisi, Y I; Makek, M; Malakhov, A; Manion, A; Manko, V I; Mannel, E; Maruyama, T; Masumoto, S; McCumber, M; McGaughey, P L; McGlinchey, D; McKay, R; McKinney, C; Meles, A; Mendoza, M; Menegasso, R; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Milov, A; Mishra, D K; Mitchell, J T; Miyasaka, S; Mizuno, S; Mohanty, A K; Montuenga, P; Moon, T; Morrison, D P; Moskowitz, M; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Mwai, A; Nagae, T; Nagamiya, S; Nagashima, K; Nagle, J L; Nagy, M I; Nakagawa, I; Nakagomi, H; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nattrass, C; Nederlof, A; Netrakanti, P K; Nihashi, M; Niida, T; Ninomiya, K; Nishimura, S; Northacker, D; Nouicer, R; Novak, T; Novitzky, N; Nukariya, A; Nyanin, A S; O'Brien, E; Ogilvie, C A; Oide, H; Okada, K; Koop, J D Orjuela; Osborn, J D; Oskarsson, A; Österman, L; Ozawa, K; Pancake, C; Pantuev, V; Papavassiliou, V; Park, I H; Park, J S; Park, S; Park, S K; Pate, S F; Patel, L; Patel, M; Peng, J -C; Perepelitsa, D; Perera, G D N; Peresedov, V; Peressounko, D Yu; Perry, J; Petti, R; Pinkenburg, C; Pinson, R; Pisani, R P; Popule, J; Purschke, M L; Qu, H; Radhakrishnan, S; Rak, J; Ramson, B J; Ravinovich, I; Read, K F; Reynolds, D; Reynolds, R; Riabov, V; Riabov, Y; Richardson, E; Rinn, T; Riveli, N; Roach, D; Rolnick, S D; Rosati, M; Roschin, E; Rowan, Z; Rubin, J G; Rukoyatkin, P; Ryu, M S; Safonov, A; Sahlmueller, B; Saito, N; Sakaguchi, T; Sako, H; Samsonov, V; Sano, M; Sarsour, M; Sato, S; Sawada, S; Schaefer, B; Schmoll, B K; Sedgwick, K; Seele, J; Seidl, R; Sekiguchi, Y; Sen, A; Seto, R; Sett, P; Sexton, A; Shafto, E; Sharma, D; Shaver, A; Shein, I; Shibata, T -A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sicho, P; Sickles, A; Silva, C L; Silvermyr, D; Singh, B K; Singh, C P; Singh, V; Sippach, F W; Skolnik, M; Snowball, M; Solano, S; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Soumya, M; Sourikova, I V; Stankus, P W; Steinberg, P; Stenlund, E; Stepanov, M; Ster, A; Stevens, L; Stoll, S P; Stone, M R; Sugitate, T; Sukhanov, A; Sumita, T; Sun, J; Sziklai, J; Takagui, E M

2015-01-01T23:59:59.000Z

296

An Upgrade Proposal from the PHENIX Collaboration  

E-Print Network [OSTI]

In this document the PHENIX collaboration proposes a major upgrade to the PHENIX detector at the Relativistic Heavy Ion Collider. This upgrade, sPHENIX, enables an extremely rich jet and beauty quarkonia physics program addressing fundamental questions about the nature of the strongly coupled quark-gluon plasma (QGP), discovered experimentally at RHIC to be a perfect fluid. The startling dynamics of the QGP on fluid-like length scales is an emergent property of quantum chromodynamics (QCD), seemingly implicit in the Lagrangian but stubbornly hidden from view. QCD is an asymptotically free theory, but how QCD manifests as a strongly coupled fluid with specific shear viscosity near $T_C$, as low as allowed by the uncertainty principle, is as fundamental an issue as that of how confinement itself arises.

A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; R. Akimoto; J. Alexander; K. Aoki; N. Apadula; H. Asano; E. T. Atomssa; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; X. Bai; N. Bandara; B. Bannier; K. N. Barish; O. Baron; B. Bassalleck; S. Bathe; V. Baublis; S. Baumgart; A. Bazilevsky; M. Beaumier; S. Beckman; R. Belmont; G. Benjamin; A. Berdnikov; Y. Berdnikov; J. Blackburn; D. S. Blau; M. Bobrek; J. Bok; S. Boose; K. Boyle; C. L. Britton, Jr.; M. L. Brooks; J. Bryslawskyj; V. Bumazhnov; C. Butler; S. Butsyk; S. Campbell; A. Carollo; J. -S. Chai; C. -H. Chen; S. Chernichenko; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; S. Choi; S. Chollet; P. Christiansen; T. Chujo; V. Cianciolo; Z. Citron; B. A. Cole; N. Cronin; N. Crossett; M. Csanád; L. D'Orazio; S. Dairaku; D. Danley; A. Datta; M. S. Daugherity; G. David; K. DeBlasio; A. Debraine; K. Dehmelt; A. Denisov; A. Deshpande; E. J. Desmond; O. Dietzsch; L. Ding; A. Dion; P. B. Diss; J. H. Do; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; J. M. Durham; A. Durum; L. Eberle; Y. V. Efremenko; T. Engelmore; A. Enokizono; S. Esumi; K. O. Eyser; B. Fadem; N. Feege; D. E. Fields; M. Finger; M. FingerJr.; F. Fleuret; S. L. Fokin; J. E. Frantz; A. Franz; A. D. Frawley; Y. Fukao; T. Fusayasu; K. Gainey; C. Gal; P. Gallus; P. Garg; A. Garishvili; I. Garishvili; F. Gastaldi; H. Ge; P. Giannotti; F. Giordarno; A. Glenn; X. Gong; M. Gonin; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; M. Grosse Perdekamp; Y. Gu; T. Gunji; H. Guragain; T. Hachiya; J. S. Haggerty; K. I. Hahn; H. Hamagaki; H. F. Hamilton; S. Y. Han; J. Hanks; S. Hasegawa; T. O. S. Haseler; K. Hashimoto; R. Hayano; S. Hayashi; X. He; T. K. Hemmick; T. Hester; J. C. Hill; M. Hoefferkamp; R. S. Hollis; K. Homma; B. Hong; Y. Hori; T. Hoshino; J. Huang; S. Huang; J. R. Hutchins; T. Ichihara; Y. Ikeda; K. Imai; Y. Imazu; J. Imrek; M. Inaba; A. Iordanova; D. Isenhower; A. Isinhue; A. Isupov; D. Ivanischev; V. Ivanov; B. V. Jacak; S. J. Jeon; M. Jezghani; J. Jia; X. Jiang; B. M. Johnson; K. S. Joo; D. Jouan; D. S. Jumper; J. Kamin; S. Kanda; B. H. Kang; J. H. Kang; J. S. Kang; J. Kapustinsky; K. Karatsu; D. Kawall; A. V. Kazantsev; H. -J. Kehayias; J. A. Key; V. Khachatryan; P. K. Khandai; A. Khanzadeev; K. M. Kijima; C. Kim; D. H. Kim; D. J. Kim; E. -J. Kim; H. J. Kim; K. -B. Kim; M. Kim; Y. -J. Kim; Y. K. Kim; B. Kimelman; Á. Kiss; E. Kistenev; R. Kitamura; J. Klatsky; D. Kleinjan; P. Kline; T. Koblesky; L. Kochenda; M. Kofarago; Y. Komatsu; B. Komkov; J. Koster; D. Kotchetkov; D. Kotov; P. Kravtsov; F. Krizek; K. Kurita; M. Kuriyama; M. Kurosawa; Y. Kwon; R. Lacey; Y. S. Lai; J. G. Lajoie; A. Lebedev; G. H. Lee; J. Lee; K. B. Lee; K. S. Lee; S. Lee; S. H. Lee; R. Lefferts; M. J. Leitch; M. A. L. Leite; M. Leitgab; B. Lewis; X. Li; S. H. Lim; A. Lipski; A. Litvinenko; M. X. Liu; B. Love; D. Lynch; M. Lynch; C. F. Maguire; Y. I. Makdisi; M. Makek; A. Malakhov; A. Manion; V. I. Manko; E. Mannel; T. Maruyama; S. Masumoto; M. McCumber; P. L. McGaughey; D. McGlinchey; R. McKay; C. McKinney; A. Meles; M. Mendoza; R. Menegasso; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; A. Milov; D. K. Mishra; J. T. Mitchell; S. Miyasaka; S. Mizuno; A. K. Mohanty; P. Montuenga; T. Moon; D. P. Morrison; M. Moskowitz; S. Motschwiller; T. V. Moukhanova; T. Murakami; J. Murata; A. Mwai; T. Nagae; S. Nagamiya; K. Nagashima; J. L. Nagle; M. I. Nagy; I. Nakagawa; H. Nakagomi; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; C. Nattrass; A. Nederlof; P. K. Netrakanti; M. Nihashi; T. Niida; K. Ninomiya; S. Nishimura; D. Northacker; R. Nouicer; T. Novak; N. Novitzky; A. Nukariya; A. S. Nyanin; E. O'Brien; C. A. Ogilvie; H. Oide; K. Okada; J. D. Orjuela Koop; J. D. Osborn; A. Oskarsson; L. Österman; K. Ozawa; C. Pancake; V. Pantuev; V. Papavassiliou; I. H. Park; J. S. Park; S. Park; S. K. Park; S. F. Pate; L. Patel; M. Patel; J. -C. Peng; D. Perepelitsa; G. D. N. Perera; V. Peresedov; D. Yu. Peressounko; J. Perry; R. Petti; C. Pinkenburg; R. Pinson; R. P. Pisani; J. Popule; M. L. Purschke; H. Qu; S. Radhakrishnan; J. Rak; B. J. Ramson; I. Ravinovich; K. F. Read; D. Reynolds; R. Reynolds; V. Riabov; Y. Riabov; E. Richardson; T. Rinn; N. Riveli; D. Roach; S. D. Rolnick; M. Rosati; E. Roschin; Z. Rowan; J. G. Rubin; P. Rukoyatkin; M. S. Ryu; A. Safonov; B. Sahlmueller; N. Saito; T. Sakaguchi; H. Sako; V. Samsonov; M. Sano; M. Sarsour; S. Sato; S. Sawada; B. Schaefer; B. K. Schmoll; K. Sedgwick; J. Seele; R. Seidl; Y. Sekiguchi; A. Sen; R. Seto; P. Sett; A. Sexton; E. Shafto; D. Sharma; A. Shaver; I. Shein; T. -A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; P. Sicho; A. Sickles; C. L. Silva; D. Silvermyr; B. K. Singh; C. P. Singh; V. Singh; F. W. Sippach; M. Skolnik; M. Snowball; S. Solano; A. Soldatov; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; M. Soumya; I. V. Sourikova; P. W. Stankus

2015-01-25T23:59:59.000Z

297

Quantum-Space Attacks  

E-Print Network [OSTI]

Theoretical quantum key distribution (QKD) protocols commonly rely on the use of qubits (quantum bits). In reality, however, due to practical limitations, the legitimate users are forced to employ a larger quantum (Hilbert) space, say a quhexit (quantum six-dimensional) space, or even a much larger quantum Hilbert space. Various specific attacks exploit of these limitations. Although security can still be proved in some very special cases, a general framework that considers such realistic QKD protocols, as well as} attacks on such protocols, is still missing. We describe a general method of attacking realistic QKD protocols, which we call the `quantum-space attack'. The description is based on assessing the enlarged quantum space actually used by a protocol, the `quantum space of the protocol'. We demonstrate these new methods by classifying various (known) recent attacks against several QKD schemes, and by analyzing a novel attack on interferometry-based QKD.

Ran Gelles; Tal Mor

2007-11-25T23:59:59.000Z

298

Generalized concatenated quantum codes  

E-Print Network [OSTI]

We discuss the concept of generalized concatenated quantum codes. This generalized concatenation method provides a systematical way for constructing good quantum codes, both stabilizer codes and nonadditive codes. Using ...

Grassl, Markus

299

Efficient distributed quantum computing  

E-Print Network [OSTI]

We provide algorithms for efficiently moving and addressing quantum memory in parallel. These imply that the standard circuit model can be simulated with a low overhead by a more realistic model of a distributed quantum ...

Beals, Robert

300

Search for the QCD Critical Point: Higher Moments of Net-proton Multiplicity Distributions  

E-Print Network [OSTI]

Higher moments of event-by-event net-proton multiplicity distributions have been applied to search for the QCD critical point. Model results are used to provide a baseline for this search. The measured moment products, $\\kappa\\sigma^2$ and $S\\sigma$ of net-proton distributions, which are directly connected to the thermodynamical baryon number susceptibility ratio in Lattice QCD and Hadron Resonance Gas (HRG) model, are compared to the transport and thermal model results. We argue that a non-monotonic dependence of $\\kappa \\sigma^2$ and $S \\sigma$ as a function of beam energy can be used to search for the QCD critical point.

Xiaofeng Luo; Bedangadas Mohanty; Hans Georg Ritter; Nu Xu

2011-05-25T23:59:59.000Z

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301

Free energy of static quarks and the renormalized Polyakov loop in full QCD  

E-Print Network [OSTI]

We present results from a detailed study of singlet free energies in full QCD with realistic quark masses. An improved scheme for the non-perturbative renormalization of the Polyakov loop is used and we compare its temperature dependence for QCD with different flavor content. We also analyze screening masses extracted from singlet free energies at various temperatures close to and above the QCD transition temperature. We conclude that the temperature dependence of screening masses is well described by perturbation theory up to a non-perturbative pre-factor. An effective running coupling has been determined for all temperature values giving additional insight into screening phenomena at high temperature.

K. Petrov; for the RBC-Bielefeld Collaboration

2007-10-23T23:59:59.000Z

302

Lattice QCD and Hydro/Cascade Model of Heavy Ion Collisions  

E-Print Network [OSTI]

We report here on a recent lattice study of the QCD transition region at finite temperature and zero chemical potential using domain wall fermions (DWF). We also present a parameterization of the QCD equation of state obtained from lattice QCD that is suitable for use in hydrodynamics studies of heavy ion collisions. Finally, we show preliminary results from a multi-stage hydrodynamics/hadron cascade model of a heavy ion collision, in an attempt to understand how well the experimental data (e.g. particle spectra, elliptic flow, and HBT radii) can constrain the inputs (e.g. initial temperature, freezeout temperature, shear viscosity, equation of state) of the theoretical model.

Michael Cheng

2010-05-11T23:59:59.000Z

303

Susceptibilities in the PNJL model with 8q interactions and comparison with lQCD  

E-Print Network [OSTI]

We present some results pertaining quantities which are regarded as good indicators of the pseudo-critical temperatures for the deconfinement and partial chiral restoration transitions using a polynomial form for the Polyakov potential part and an extended version of the NJL model which includes 6 and 8 quark interaction terms. Some comparisons with results from the lattice formulation of QCD (lQCD) are performed and results for the location of the critical endoint in the phase diagram are also presented. It is shown that the comparison with lQCD results favors a moderately strong OZI-violating 8 quark interaction term.

João Moreira; Brigitte Hiller; Alexander Osipov; Alex Blin

2013-02-06T23:59:59.000Z

304

A dynamical model for longitudinal wave functions in light-front holographic QCD  

E-Print Network [OSTI]

We construct a Schrodinger-like equation for the longitudinal wave function of a meson in the valence qq-bar sector, based on the 't Hooft model for large-N two-dimensional QCD, and combine this with the usual transverse equation from light-front holographic QCD, to obtain a model for mesons with massive quarks. The computed wave functions are compared with the wave function ansatz of Brodsky and De Teramond and used to compute decay constants and parton distribution functions. The basis functions used to solve the longitudinal equation may be useful for more general calculations of meson states in QCD.

S. S. Chabysheva; J. R. Hiller

2013-07-14T23:59:59.000Z

305

Nonequilibrium quantum kinetics  

SciTech Connect (OSTI)

This paper contains viewgraphs on non-equilibrium quantum kinetics of nuclear reactions at the intermediate and high energy ranges.

Danielewicz, P.

1997-09-22T23:59:59.000Z

306

Changing quantum reference frames  

E-Print Network [OSTI]

We consider the process of changing reference frames in the case where the reference frames are quantum systems. We find that, as part of this process, decoherence is necessarily induced on any quantum system described relative to these frames. We explore this process with examples involving reference frames for phase and orientation. Quantifying the effect of changing quantum reference frames serves as a first step in developing a relativity principle for theories in which all objects including reference frames are necessarily quantum.

Matthew C. Palmer; Florian Girelli; Stephen D. Bartlett

2014-05-21T23:59:59.000Z

307

Generalized Concatenated Quantum Codes  

E-Print Network [OSTI]

We introduce the concept of generalized concatenated quantum codes. This generalized concatenation method provides a systematical way for constructing good quantum codes, both stabilizer codes and nonadditive codes. Using this method, we construct families of new single-error-correcting nonadditive quantum codes, in both binary and nonbinary cases, which not only outperform any stabilizer codes for finite block length, but also asymptotically achieve the quantum Hamming bound for large block length.

Markus Grassl; Peter Shor; Graeme Smith; John Smolin; Bei Zeng

2009-01-09T23:59:59.000Z

308

Quantum money from knots  

E-Print Network [OSTI]

Quantum money is a cryptographic protocol in which a mint can produce a quantum state, no one else can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint. We present a concrete quantum money scheme based on superpositions of diagrams that encode oriented links with the same Alexander polynomial. We expect our scheme to be secure against computationally bounded adversaries.

Edward Farhi; David Gosset; Avinatan Hassidim; Andrew Lutomirski; Peter Shor

2010-04-28T23:59:59.000Z

309

Quantum chaos in quantum Turing machines  

E-Print Network [OSTI]

We investigate a 2-spin quantum Turing architecture, in which discrete local rotations \\alpha_m of the Turing head spin alternate with quantum controlled NOT-operations. We demonstrate that a single chaotic parameter input \\alpha_m leads to a chaotic dynamics in the entire Hilbert-space.

Ilki Kim; Guenter Mahler

1999-10-18T23:59:59.000Z

310

Stephen Hawking Quantum Gravity  

E-Print Network [OSTI]

Stephen Hawking and Quantum Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 4 Nov 2000 #12; Stephen Hawking and Quantum Gravity Abstract: Through research, Stephen Hawking has captured a place in the popular imagina- tion. Quantum gravity in its various

Visser, Matt

311

Quantum Circuits Architecture  

E-Print Network [OSTI]

We present a method for optimizing quantum circuits architecture. The method is based on the notion of "quantum comb", which describes a circuit board in which one can insert variable subcircuits. The method allows one to efficiently address novel kinds of quantum information processing tasks, such as storing-retrieving, and cloning of channels.

Giulio Chiribella; Giacomo Mauro D'Ariano; Paolo Perinotti

2007-12-09T23:59:59.000Z

312

Quantum money from knots  

E-Print Network [OSTI]

Quantum money is a cryptographic protocol in which a mint can produce a quantum state, no one else can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint. We present a concrete ...

Farhi, Edward

313

Fractional electric charge and quark confinement  

E-Print Network [OSTI]

Owing to their fractional electric charges, quarks are blind to transformations that combine a color center phase with an appropriate electromagnetic one. Such transformations are part of a global $Z_6$-like center symmetry of the Standard Model that is lost when quantum chromodynamics (QCD) is treated as an isolated theory. This symmetry and the corresponding topological defects may be relevant to non-perturbative phenomena such as quark confinement, much like center symmetry and ordinary center vortices are in pure SU($N$) gauge theories. Here we report on our investigations of an analogous symmetry in a 2-color model with dynamical Wilson quarks carrying half-integer electric charge.

Sam R. Edwards; André Sternbeck; Lorenz von Smekal

2012-02-07T23:59:59.000Z

314

Chemical freeze-out parameters in Beam Energy Scan Program of STAR at RHIC  

E-Print Network [OSTI]

The STAR experiment at RHIC has completed its first phase of the Beam Energy Scan (BES-I) program to understand the phase structure of the quantum chromodynamics (QCD). The bulk properties of the system formed in Au+Au collisions at different center of mass energy $\\sqrt{s_{NN}} = $ 7.7, 11.5, 19.6, 27, and 39 GeV have been studied from the data collected in the year 2010 and 2011. The centrality and energy dependence of mid-rapidity ($|y|$ chemical freeze-out parameters are extracted using measured particle ratios within the framework of a statistical model.

Sabita Das

2014-12-01T23:59:59.000Z

315

The beam energy dependence of collective flow in heavy ion collisions  

E-Print Network [OSTI]

The major goals of heavy ion research are to explore the phase diagram of quantum chromodynamics (QCD) and to investigate the properties of the quark gluon plasma (QGP), a new state of matter created at high temperatures and/or densities. Collective anisotropic flow is one of the most promising observables to gain insights about the properties of the system created in relativistic heavy ion reactions. The current status of the beam energy dependence of the first three Fourier coefficients of the azimuthal distribution of the produced particles $v_1$ to $v_3$ within hybrid transport plus hydrodynamics approaches are summarized.

Petersen, Hannah; Auvinen, Jussi; Bleicher, Marcus

2015-01-01T23:59:59.000Z

316

The beam energy dependence of collective flow in heavy ion collisions  

E-Print Network [OSTI]

The major goals of heavy ion research are to explore the phase diagram of quantum chromodynamics (QCD) and to investigate the properties of the quark gluon plasma (QGP), a new state of matter created at high temperatures and/or densities. Collective anisotropic flow is one of the most promising observables to gain insights about the properties of the system created in relativistic heavy ion reactions. The current status of the beam energy dependence of the first three Fourier coefficients of the azimuthal distribution of the produced particles $v_1$ to $v_3$ within hybrid transport plus hydrodynamics approaches are summarized.

Hannah Petersen; Jan Steinheimer; Jussi Auvinen; Marcus Bleicher

2015-03-11T23:59:59.000Z

317

Search for the decay (B)over-bar(0) -> D*(0)gamma  

E-Print Network [OSTI]

? B 0 ! D H115690 g (and its charge conjugate state). In the SM framework this decay pro- ceeds via W exchange between b and ? d quarks (Fig. 1). Naively, this transition is suppressed by helicity effects and quantum chromodynamic (QCD) color... was replaced by a silicon vertex detector [10] and the argon-ethane gas of the main drift chamber was changed to a helium-propane mixture. This upgrade led to improved resolutions in momentum and specific ionization energy loss (dEH20862dx). The response...

Ammar, Raymond G.; Bean, Alice; Besson, David Zeke; Davis, Robin E. P.; Kwak, Nowhan; Zhao, X.

2000-05-01T23:59:59.000Z

318

Toward the excited isoscalar meson spectrum from lattice QCD  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We report on the extraction of an excited spectrum of isoscalar mesons using lattice QCD. Calculations on several lattice volumes are performed with a range of light quark masses corresponding to pion masses down to about ~400 MeV. The distillation method enables us to evaluate the required disconnected contributions with high statistical precision for a large number of meson interpolating fields. We find relatively little mixing between light and strange in most JPC channels; one notable exception is the pseudoscalar sector where the approximate SU(3)F octet, singlet structure of the ?, ?' is reproduced. We extract exotic JPC states, identified as hybrid mesons in which an excited gluonic field is coupled to a color-octet qqbar pair, along with non-exotic hybrid mesons embedded in a qqbar-like spectrum.

Edwards, Robert G. [JLAB; Dudek, Jozef J. [JLAB, Old Dominion U.; Thomas, Christopher Edward [Trinity College, Dublin; Guo, Peng [Indiana U.

2013-11-01T23:59:59.000Z

319

QCD thermodynamics with continuum extrapolated Wilson fermions II  

E-Print Network [OSTI]

We continue our investigation of 2+1 flavor QCD thermodynamics using dynamical Wilson fermions in the fixed scale approach. Two additional pion masses, approximately 440 MeV and 285 MeV, are added to our previous work at 545 MeV. The simulations were performed at 3 or 4 lattice spacings at each pion mass. The renormalized chiral condensate, strange quark number susceptibility and Polyakov loop is obtained as a function of the temperature and we observe a decrease in the light chiral pseudo-critical temperature as the pion mass is lowered while the pseudo-critical temperature associated with the strange quark number susceptibility or the Polyakov loop is only mildly sensitive to the pion mass. These findings are in agreement with previous continuum results obtained in the staggered formulation.

Szabolcs Borsanyi; Stephan Durr; Zoltan Fodor; Christian Holbling; Sandor D. Katz; Stefan Krieg; Daniel Nogradi; Kalman K. Szabo; Balint C. Toth; Norbert Trombitas

2015-04-14T23:59:59.000Z

320

QCD thermodynamics with continuum extrapolated Wilson fermions II  

E-Print Network [OSTI]

We continue our investigation of 2+1 flavor QCD thermodynamics using dynamical Wilson fermions in the fixed scale approach. Two additional pion masses, approximately 440 MeV and 285 MeV, are added to our previous work at 545 MeV. The simulations were performed at 3 or 4 lattice spacings at each pion mass. The renormalized chiral condensate, strange quark number susceptibility and Polyakov loop is obtained as a function of the temperature and we observe a decrease in the light chiral pseudo-critical temperature as the pion mass is lowered while the pseudo-critical temperature associated with the strange quark number susceptibility or the Polyakov loop is only mildly sensitive to the pion mass. These findings are in agreement with previous continuum results obtained in the staggered formulation.

Borsanyi, Szabolcs; Fodor, Zoltan; Holbling, Christian; Katz, Sandor D; Krieg, Stefan; Nogradi, Daniel; Szabo, Kalman K; Toth, Balint C; Trombitas, Norbert

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Magnetic catalysis and inverse magnetic catalysis in QCD  

E-Print Network [OSTI]

We investigate the effects of strong magnetic fields on the QCD phase structure at vanishing density by solving the gluon and quark gap equations, and by studying the dynamics of the quark scattering with the four-fermi coupling. The chiral crossover temperature as well as the chiral condensate are computed. For asymptotically large magnetic fields we find magnetic catalysis, while we find inverse magnetic catalysis for intermediate magnetic fields. Moreover, for large magnetic fields the chiral phase transition for massless quarks turns into a crossover. The underlying mechanisms are then investigated analytically within a few simplifications of the full numerical analysis. We find that a combination of gluon screening effects and the weakening of the strong coupling is responsible for the phenomenon of inverse catalysis. In turn, the magnetic catalysis at large magnetic field is already indicated by simple arguments based on dimensionality.

Niklas Mueller; Jan M. Pawlowski

2015-02-27T23:59:59.000Z

322

Nuclear matter to strange matter transition in holographic QCD  

E-Print Network [OSTI]

We construct a simple holographic QCD model to study nuclear matter to strange matter transition. The interaction of dense medium and hadrons is taken care of by imposing the force balancing condition for stable D4/D6/D6 configuration. By considering the intermediate and light flavor branes interacting with baryon vertex homogeneously distributed along R^3 space and requesting the energy minimization, we find that there is a well defined transition density as a function of current quark mass. We also find that as density goes up very high, intermediate (or heavy) and light quarks populate equally as expected from the Pauli principle. In this sense, the effect of the Pauli principle is realized as dynamics of D-branes.

Youngman Kim; Yunseok Seo; Sang-Jin Sin

2009-11-19T23:59:59.000Z

323

The infrared behavior of lattice QCD Green's functions  

E-Print Network [OSTI]

We investigate different aspects of lattice QCD in Landau gauge using Monte Carlo simulations. In particular, we focus on the low momentum behavior of gluon and ghost propagators. The gauge group is SU(3). Different systematic effects on the gluon and ghost propagators are studied, e.g. the dependence on the choice of Gribov copies or the influence of dynamical Wilson fermions. We compare our data with results from studies of Dyson-Schwinger equations for the gluon and ghost propagators. We demonstrate that the infrared behavior of both propagators, as found in this thesis, is consistent with different criteria for confinement. However, the running coupling constant, given as a renormalization-group-invariant combination of the gluon and ghost dressing functions, does not expose a finite infrared fixed point. We also report on a first nonperturbative computation of the SU(3) ghost-gluon-vertex renormalization constant and on an investigation of the spectral properties of the Faddeev-Popov operator.

Andre Sternbeck

2006-09-08T23:59:59.000Z

324

Transverse momentum-dependent parton distribution functions in lattice QCD  

SciTech Connect (OSTI)

A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.

Engelhardt, Michael G. [New Mexico State University; Musch, Bernhard U. [Tech. University Munich; Haegler, Philipp G. [Tech. University Munich; Negele, John W. [MIT; Schaefer, Andreas [Regensburg

2013-08-01T23:59:59.000Z

325

The Emerging QCD Frontier: The Electron Ion Collider  

E-Print Network [OSTI]

The self-interactions of gluons determine all the unique features of QCD and lead to a dominant abundance of gluons inside matter already at moderate $x$. Despite their dominant role, the properties of gluons remain largely unexplored. Tantalizing hints of saturated gluon densities have been found in $e$+p collisions at HERA, and in d+Au and Au+Au collisions at RHIC. Saturation physics will have a profound influence on heavy-ion collisions at the LHC. But unveiling the collective behavior of dense assemblies of gluons under conditions where their self-interactions dominate will require an Electron-Ion Collider (EIC): a new facility with capabilities well beyond those In this paper I outline the compelling physics case for $e$+A collisions at an EIC and discuss briefly the status of machine design concepts. of any existing accelerator.

Thomas Ullrich

2008-05-31T23:59:59.000Z

326

Contact Term, its Holographic Description in QCD and Dark Energy  

E-Print Network [OSTI]

In this work we study the well known contact term, which is the key element in resolving the so-called $U(1)_A$ problem in QCD. We study this term using the dual Holographic Description. We argue that in the dual picture the contact term is saturated by the D2 branes which can be interpreted as the tunnelling events in Minkowski space-time. We quote a number of direct lattice results supporting this identification. We also argue that the contact term receives a Casimir -like correction $\\sim (\\Lqcd R)^{-1}$ rather than naively expected $\\exp(-\\Lqcd R)$ when the Minkowski space-time ${\\cal R}_{3,1}$ is replaced by a large but finite manifold with a size $R$. Such a behaviour is consistent with other QFT-based computations when power like corrections are due to nontrivial properties of topological sectors of the theory. In holographic description such a behaviour is due to massless Ramond-Ramond (RR) field living in the bulk of multidimensional space when power like corrections is a natural outcome of massless RR field. In many respects the phenomenon is similar to the Aharonov -Casher effect when the "modular electric field" can penetrate into a superconductor where the electric field is exponentially screened. The role of "modular operator" from Aharonov -Casher effect is played by large gauge transformation operator $\\cal{T}$ in 4d QCD, resulting the transparency of the system to topologically nontrivial pure gauge configurations. We discuss some profound consequences of our findings. In particular, we speculate that a slow variation of the contact term in expanding universe might be the main source of the observed Dark Energy.

Ariel R. Zhitnitsky

2012-08-01T23:59:59.000Z

327

Discovering the QCD Axion with Black Holes and Gravitational Waves  

E-Print Network [OSTI]

Advanced LIGO will be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant above the GUT scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom." Through the superradiance process, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. Axions transitioning between levels of the gravitational atom and axions annihilating to gravitons produce observable gravitational wave signals. The signals are long-lasting, monochromatic, and can be distinguished from ordinary astrophysical sources. We estimate up to O(1) transition events at aLIGO for an axion between 10^-11 and 10^-10 eV and up to 10^4 annihilation events for an axion between 10^-13 and 10^-11 eV. In the event of a null search, aLIGO can constrain the axion mass as a function of the formation rate of rapidly spinning black holes. Axion annihilations are also promising for much lighter masses at future lower-frequency gravitational wave observatories, where we expect as many as $10^5$ events. Our projections for aLIGO are robust against perturbations from the black hole environment and account for our updated exclusion on the QCD axion of 6 * 10^-13 eV < ma < 2 * 10^-11 eV suggested by stellar black hole spin measurements.

Asimina Arvanitaki; Masha Baryakhtar; Xinlu Huang

2014-12-15T23:59:59.000Z

328

AdS/CFT and Exclusive Processes in QCD  

E-Print Network [OSTI]

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. One can use holography to map the amplitude describing the hadronic state in the fifth dimension of Anti-de Sitter space to the light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons in QCD at the amplitude level. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable zeta which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. New relativistic light-front equations in ordinary space-time can then be derived which reproduce the results obtained using the 5-dimensional theory. The effective light-front equations possess elegant algebraic structures and integrability properties. This connection between the AdS and the light-front representations allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties and allow the computation of decay constants, form factors, deeply virtual Compton scattering, exclusive heavy hadron decays and other exclusive scattering amplitudes. As specific examples we compute the pion coupling constant and study the behavior of the pion form factor in the space and time-like regions. We also determine the Dirac form factors of the proton and neutron in the space-like region.

Stanley J. Brodsky; Guy F. de Teramond

2007-09-13T23:59:59.000Z

329

Extended quantum color coding  

SciTech Connect (OSTI)

The quantum color coding scheme proposed by Korff and Kempe [e-print quant-ph/0405086] is easily extended so that the color coding quantum system is allowed to be entangled with an extra auxiliary quantum system. It is shown that in the extended scheme we need only {approx}2{radical}(N) quantum colors to order N objects in large N limit, whereas {approx}N/e quantum colors are required in the original nonextended version. The maximum success probability has asymptotics expressed by the Tracy-Widom distribution of the largest eigenvalue of a random Gaussian unitary ensemble (GUE) matrix.

Hayashi, A.; Hashimoto, T.; Horibe, M. [Department of Applied Physics, Fukui University, Fukui 910-8507 (Japan)

2005-01-01T23:59:59.000Z

330

Hierarchical quantum communication  

E-Print Network [OSTI]

A general approach to study the hierarchical quantum information splitting (HQIS) is proposed and the same is used to systematically investigate the possibility of realizing HQIS using different classes of 4-qubit entangled states that are not connected by SLOCC. Explicit examples of HQIS using 4-qubit cluster state and 4-qubit |\\Omega> state are provided. Further, the proposed HQIS scheme is generalized to introduce two new aspects of hierarchical quantum communication. To be precise, schemes of probabilistic hierarchical quantum information splitting and hierarchical quantum secret sharing are obtained by modifying the proposed HQIS scheme. A number of practical situations where hierarchical quantum communication would be of use are also presented.

Chitra Shukla; Anirban Pathak

2013-01-03T23:59:59.000Z

331

Quantum Physics and Nanotechnology  

E-Print Network [OSTI]

Experimental studies of infinite (unrestricted at least in one direction) quantum particle motion using probe nanotechnologies have revealed the necessity of revising previous concepts of their motion. Particularly, quantum particles transfer quantum motion nonlocality energy beside classical kinetic energy, in other words, they are in two different kinds of motion simultaneously. The quantum component of the motion energy may be quite considerable under certain circumstances. Some new effects were predicted and proved experimentally in terms of this phenomenon. A new prototype refrigerating device was tested, its principle of operation being based on the effect of transferring the quantum component of the motion energy.

Vladimir K. Nevolin

2011-06-06T23:59:59.000Z

332

Quantum ballistic evolution in quantum mechanics: Application to quantum computers  

SciTech Connect (OSTI)

Quantum computers are important examples of processes whose evolution can be described in terms of iterations of single-step operators or their adjoints. Based on this, Hamiltonian evolution of processes with associated step operators {ital T} is investigated here. The main limitation of this paper is to processes which evolve quantum ballistically, i.e., motion restricted to a collection of nonintersecting or distinct paths on an arbitrary basis. The main goal of this paper is proof of a theorem which gives necessary and sufficient conditions that {ital T} must satisfy so that there exists a Hamiltonian description of quantum ballistic evolution for the process, namely, that {ital T} is a partial isometry and is orthogonality preserving and stable on some basis. Simple examples of quantum ballistic evolution for quantum Turing machines with one and with more than one type of elementary step are discussed. It is seen that for nondeterministic machines the basis set can be quite complex with much entanglement present. It is also proven that, given a step operator {ital T} for an arbitrary {ital deterministic} quantum Turing machine, it is decidable if {ital T} is stable and orthogonality preserving, and if quantum ballistic evolution is possible. The proof fails if {ital T} is a step operator for a {ital nondeterministic} machine. It is an open question if such a decision procedure exists for nondeterministic machines. This problem does not occur in classical mechanics. Also the definition of quantum Turing machines used here is compared with that used by other authors. {copyright} {ital 1996 The American Physical Society.}

Benioff, P. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

1996-08-01T23:59:59.000Z

333

Explorations of the quark substructure of the nucleon in lattice QCD  

E-Print Network [OSTI]

Lattice gauge theory is a valuable tool for understanding how properties of the nucleon arise from the fundamental interactions of QCD. Numerical computations on the lattice can be used not only for first principles ...

Bratt, Jonathan D. (Jonathan Daniel)

2009-01-01T23:59:59.000Z

334

Decays of excited baryons in the large Nc expansion of QCD  

SciTech Connect (OSTI)

We present the analysis of the decay widths of excited baryons in the framework of the 1/Nc expansion of QCD. These studies are performed up to order 1/Nc and include both positive and negative parity excited baryons.

Jose Goity; Norberto Scoccola

2006-05-06T23:59:59.000Z

335

Reconciling the analytic QCD with the ITEP operator product expansion philosophy  

E-Print Network [OSTI]

Analytic QCD models are those versions of QCD in which the running coupling parameter a(Q^2) has the same analytic properties as the spacelike physical quantities, i.e., no singularities in the complex Q^2 plane except on the timelike semiaxis. In such models, a(Q^2) usually differs from its perturbative analog by power terms ~(Lambda^2/Q^2)^k for large momenta, introducing thus nonperturbative terms in spacelike physical quantities whose origin is the UV regime. Consequently, it contradicts the ITEP-OPE philosophy which states that such terms can come only from the IR regimes. We investigate whether it is possible to construct analytic QCD models which respect the ITEP-OPE philosophy and, at the same time, reproduce not just the high-energy QCD observables, but also the low-energy ones, among them the well-measured semihadronic tau decay ratio.

Gorazd Cvetic; Reinhart Koegerler; Cristian Valenzuela

2010-06-22T23:59:59.000Z

336

Collimation of energy in medium-modified QCD jets Redamy Perez-Ramos 1  

E-Print Network [OSTI]

energy is found to broaden in QCD media. 1 e-mail: redamy.perez@uv.es 2 e-mail: vincent, it has been confirmed that highly virtual partons produced in such reactions suffer an energy degradation

337

Magnetic and electric contributions to the energy loss in a dynamical QCD medium  

E-Print Network [OSTI]

The computation of radiative energy loss in a finite size QCD medium with dynamical constituents is a key ingredient for obtaining reliable predictions for jet quenching in ultra-relativistic heavy ion collisions. It was previously shown that energy loss in dynamical QCD medium is significantly higher compared to static QCD medium. To understand this difference, we here analyze magnetic and electric contributions to energy loss in dynamical QCD medium. We find that the significantly higher energy loss in the dynamical case is entirely due to appearance of magnetic contribution in the dynamical medium. While for asymptotically high energies, the energy loss in static and dynamical medium approach the same value, we find that the physical origin of the energy loss in these two cases is different.

Magdalena Djordjevic

2011-05-21T23:59:59.000Z

338

Nuclear physics in soft-wall AdS/QCD: deuteron electromagnetic form factors  

E-Print Network [OSTI]

We present a calculation of the deuteron electromagnetic form factors in a soft-wall AdS/QCD approach. The power scaling of the deuteron form factors is consistent with quark counting rules.

Gutsche, Thomas; Schmidt, Ivan; Vega, Alfredo

2015-01-01T23:59:59.000Z

339

Perturbative renormalization of proton observables in lattice QCD using domain wall fermions  

E-Print Network [OSTI]

Deep inelastic scattering unambiguously measures hadron observables characterizing the quark-gluon structure of hadrons. The only way to calculate these observables from first principles is lattice QCD. Experiments measure ...

Bistrović , Bojan

2005-01-01T23:59:59.000Z

340

Determination of the ?(1232) axial and pseudoscalar form factors from lattice QCD  

E-Print Network [OSTI]

We present a lattice QCD calculation of the ?(1232) matrix elements of the axial-vector and pseudoscalar currents. The decomposition of these matrix elements into the appropriate Lorentz invariant form factors is carried ...

Alexandrou, Constantia

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Exploration of the role of diquarks in hadrons using lattice QCD  

E-Print Network [OSTI]

We perform a number of measurements relevant to nuclear and particle physics by using the tools of lattice QCD. We verify our lattice calculations by reproducing published meson masses. We then study the light quark ...

Varilly, Patrick S

2006-01-01T23:59:59.000Z

342

Adiabatic Quantum Transistors  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We describe a many-body quantum system that can be made to quantum compute by the adiabatic application of a large applied field to the system. Prior to the application of the field, quantum information is localized on one boundary of the device, and after the application of the field, this information propagates to the other side of the device, with a quantum circuit applied to the information. The applied circuit depends on the many-body Hamiltonian of the material, and the computation takes place in a degenerate ground space with symmetry-protected topological order. Such “adiabatic quantum transistors” are universal adiabatic quantum computing devices that have the added benefit of being modular. Here, we describe this model, provide arguments for why it is an efficient model of quantum computing, and examine these many-body systems in the presence of a noisy environment.

Bacon, Dave; Flammia, Steven T.; Crosswhite, Gregory M.

2013-06-01T23:59:59.000Z

343

Trajectories without quantum uncertainties  

E-Print Network [OSTI]

A common knowledge suggests that trajectories of particles in quantum mechanics always have quantum uncertainties. These quantum uncertainties set by the Heisenberg uncertainty principle limit precision of measurements of fields and forces, and ultimately give rise to the standard quantum limit in metrology. With the rapid developments of sensitivity of measurements these limits have been approached in various types of measurements including measurements of fields and acceleration. Here we show that a quantum trajectory of one system measured relatively to the other "reference system" with an effective negative mass can be quantum uncertainty--free. The method crucially relies on the generation of an Einstein-Podolsky-Rosen entangled state of two objects, one of which has an effective negative mass. From a practical perspective these ideas open the way towards force and acceleration measurements at new levels of sensitivity far below the standard quantum limit.

Eugene S. Polzik; Klemens Hammerer

2014-05-13T23:59:59.000Z

344

Adiabatic topological quantum computing  

E-Print Network [OSTI]

Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.

Chris Cesare; Andrew J. Landahl; Dave Bacon; Steven T. Flammia; Alice Neels

2014-06-10T23:59:59.000Z

345

Quantum Thermodynamic Cycles and Quantum Heat Engines (II)  

E-Print Network [OSTI]

We study the quantum mechanical generalization of force or pressure, and then we extend the classical thermodynamic isobaric process to quantum mechanical systems. Based on these efforts, we are able to study the quantum version of thermodynamic cycles that consist of quantum isobaric process, such as quantum Brayton cycle and quantum Diesel cycle. We also consider the implementation of quantum Brayton cycle and quantum Diesel cycle with some model systems, such as single particle in 1D box and single-mode radiation field in a cavity. These studies lay the microscopic (quantum mechanical) foundation for Szilard-Zurek single molecule engine.

H. T. Quan

2009-03-09T23:59:59.000Z

346

QCD condensates of dimension D=6 and D=8 from hadronic tau-decays  

E-Print Network [OSTI]

The high-precision data from hadronic tau decays allows one to extract information on QCD condensates. Using the finalized ALEPH data, we obtain a more rigorous determination of the dimension 6 and 8 condensates for the V-A correlator. In particular, we find that the recent data fix a certain linear combination of these QCD condensates to a precision at the level of O(2%). Our approach relies on more general assumptions than alternative approaches based on finite energy sum rules.

A. A. Almasy; K. Schilcher; H. Spiesberger

2006-12-22T23:59:59.000Z

347

Diagnostics of quark-gluon plasma in ultrarelativistic heavy ion collisions by hard QCD-processes  

E-Print Network [OSTI]

We analyze the possibilities for studying properties of dense QCD-matter, created in ultrarelativistic nuclear collisions, by hard QCD-production processes, so-called "hard" probes -- heavy quarkonia, hard jets, high mass dimuons. Special attention is paid to the potential of coming heavy ion experiments on Large Hadron Collider to observe the rescattering and energy losses of hard partons in quark-gluon plasma.

I. P. Lokhtin

2000-12-01T23:59:59.000Z

348

Cosmological Consequences of QCD Phase Transition(s) in Early Universe  

SciTech Connect (OSTI)

We discuss the cosmological consequences of QCD phase transition(s) on the early universe. We argue that our recent knowledge about the transport properties of quark-gluon plasma (QGP) should thraw additional lights on the actual time evolution of our universe. Understanding the nature of QCD phase transition(s), which can be studied in lattice gauge theory and verified in heavy ion experiments, provides an explanation for cosmological phenomenon stem from early universe.

Tawfik, A. [ECTP, Egyptian Center for Theoretical Physics, MTI Modern University, Mukattam Cairo (Egypt)

2009-04-17T23:59:59.000Z

349

arXiv:1311.5455v1 NLO QCD Corrections to Electroweak Higgs Boson  

E-Print Network [OSTI]

arXiv:1311.5455v1 [hep­ph] 21 Nov 2013 NLO QCD Corrections to Electroweak Higgs Boson Plus Three.sjodahl@thep.lu.se The implementation of the full next­to­leading order (NLO) QCD corrections to electroweak Higgs boson plus three jet Model (SM) Higgs boson [3, 4, 5, 6]. Further, reports from the ATLAS and CMS Collaborations indicate

Lunds Universitet,

350

REMARKS ON THE MAXIMUM ENTROPY METHOD APPLIED TO FINITE TEMPERATURE LATTICE QCD.  

SciTech Connect (OSTI)

We make remarks on the Maximum Entropy Method (MEM) for studies of the spectral function of hadronic correlators in finite temperature lattice QCD. We discuss the virtues and subtlety of MEM in the cases that one does not have enough number of data points such as at finite temperature. Taking these points into account, we suggest several tests which one should examine to keep the reliability for the results, and also apply them using mock and lattice QCD data.

UMEDA, T.; MATSUFURU, H.

2005-07-25T23:59:59.000Z

351

Remarks on the Maximum Entropy Method applied to finite temperature lattice QCD  

E-Print Network [OSTI]

We make remarks on the Maximum Entropy Method (MEM) for studies of the spectral function of hadronic correlators in finite temperature lattice QCD. We discuss the virtues and subtlety of MEM in the cases that one does not have enough number of data points such as at finite temperature. Taking these points into account, we suggest several tests which one should examine to keep the reliability for the results, and also apply them using mock and lattice QCD data.

Takashi Umeda; Hideo Matsufuru

2005-10-05T23:59:59.000Z

352

Hybrid Quantum Computation in Quantum Optics  

E-Print Network [OSTI]

We propose a hybrid quantum computing scheme where qubit degrees of freedom for computation are combined with quantum continuous variables for communication. In particular, universal two-qubit gates can be implemented deterministically through qubit-qubit communication, mediated by a continuous-variable bus mode ("qubus"), without direct interaction between the qubits and without any measurement of the qubus. The key ingredients are controlled rotations of the qubus and unconditional qubus displacements. The controlled rotations are realizable through typical atom-light interactions in quantum optics. For such interactions, our scheme is universal and works in any regime, including the limits of weak and strong nonlinearities.

P. van Loock; W. J. Munro; Kae Nemoto; T. P. Spiller; T. D. Ladd; Samuel L. Braunstein; G. J. Milburn

2007-01-11T23:59:59.000Z

353

Metastable vacuum decay and $?$ dependence in gauge theory. Deformed QCD as a toy model  

E-Print Network [OSTI]

We study a number of different ingredients related to the $\\theta$ dependence, metastable excited vacuum states and other related subjects using a simplified version of QCD, the so-called "deformed QCD". This model is a weakly coupled gauge theory, which however preserves all the relevant essential elements allowing us to study hard and nontrivial features which are known to be present in real strongly coupled QCD. Our main focus in this work is to test the ideas related to the metastable vacuum states (which are known to be present in strongly coupled QCD in large $N$ limit) in a theoretically controllable manner using the "deformed QCD" as a toy model. We explicitly show how the metastable states emerge in the system, why their life time is large, and why these metastable states must be present in the system for the self-consistency of the entire picture of the QCD vacuum. We also speculate on possible relevance of the metastable vacuum states in explanation of the violation of local $\\cal{P}$ and $\\cal{CP}$ symmetries in heavy ion collisions.

Amit Bhoonah; Evan Thomas; Ariel R. Zhitnitsky

2014-07-18T23:59:59.000Z

354

Theoretical Foundation of the Nuclear Force in QCD and its applications to Central and Tensor Forces in Quenched Lattice QCD Simulations  

E-Print Network [OSTI]

We present full accounts of a method to extract nucleon-nucleon (NN) potentials from the Bethe-Salpter amplitude in lattice QCD. The method is applied to two nucleons on the lattice with quenched QCD simulations. By disentangling the mixing between the S-state and the D-state, we obtain central and tensor potentials in the leading order of the velocity expansion of the non-local NN potential. The spatial structure and the quark mass dependence of the potentials are analyzed in detail.

Sinya Aoki; Tetsuo Hatsuda; Noriyoshi Ishii

2009-12-31T23:59:59.000Z

355

Generalized quantum defect methods in quantum chemistry  

E-Print Network [OSTI]

The reaction matrix of multichannel quantum defect theory, K, gives a complete picture of the electronic structure and the electron - nuclear dynamics for a molecule. The reaction matrix can be used to examine both bound ...

Altunata, Serhan

2006-01-01T23:59:59.000Z

356

Nested Quantum Walks with Quantum Data Structures  

E-Print Network [OSTI]

We develop a new framework that extends the quantum walk framework of Magniez, Nayak, Roland, and Santha, by utilizing the idea of quantum data structures to construct an efficient method of nesting quantum walks. Surprisingly, only classical data structures were considered before for searching via quantum walks. The recently proposed learning graph framework of Belovs has yielded improved upper bounds for several problems, including triangle finding and more general subgraph detection. We exhibit the power of our framework by giving a simple explicit constructions that reproduce both the $O(n^{35/27})$ and $O(n^{9/7})$ learning graph upper bounds (up to logarithmic factors) for triangle finding, and discuss how other known upper bounds in the original learning graph framework can be converted to algorithms in our framework. We hope that the ease of use of this framework will lead to the discovery of new upper bounds.

Stacey Jeffery; Robin Kothari; Frederic Magniez

2012-10-03T23:59:59.000Z

357

Quantum Copy-Protection and Quantum Money  

E-Print Network [OSTI]

Forty years ago, Wiesner proposed using quantum states to create money that is physically impossible to counterfeit, something that cannot be done in the classical world. However, Wiesner's scheme required a central bank ...

Aaronson, Scott

358

Thermodynamics of two-flavor lattice QCD with an improved Wilson quark action at non-zero temperature and density  

E-Print Network [OSTI]

We report the current status of our systematic studies of the QCD thermodynamics by lattice QCD simulations with two flavors of improved Wilson quarks. We evaluate the critical temperature of two flavor QCD in the chiral limit at zero chemical potential and show the preliminary result. Also we discuss fluctuations at none-zero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to chemical potential.

Y. Maezawa; S. Aoki; S. Ejiri; T. Hatsuda; N. Ishii; K. Kanaya; N. Ukita

2007-02-02T23:59:59.000Z

359

Pion distribution amplitude from holographic QCD and the electromagnetic form factor F{sub {pi}}(Q{sup 2})  

SciTech Connect (OSTI)

The holographic QCD prediction for the pion distribution amplitude (DA) {phi}{sub hol}(u) is used to compute the pion spacelike electromagnetic form factor F{sub {pi}}(Q{sup 2}) within the QCD light-cone sum rule method. In calculations the pion's renormalon-based model twist-4 DA, as well as the asymptotic twist-4 DA are employed. Obtained theoretical predictions are compared with experimental data and with results of the holographic QCD.

Agaev, S. S.; Nobary, M. A. Gomshi [Institute for Physical Problems, Baku State University, Z. Khalilov Street 23, Az-1148 Baku (Azerbaijan); Department of Physics, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of)

2008-04-01T23:59:59.000Z

360

Quantum Copy-Protection and Quantum Money  

E-Print Network [OSTI]

Forty years ago, Wiesner proposed using quantum states to create money that is physically impossible to counterfeit, something that cannot be done in the classical world. However, Wiesner's scheme required a central bank to verify the money, and the question of whether there can be unclonable quantum money that anyone can verify has remained open since. One can also ask a related question, which seems to be new: can quantum states be used as copy-protected programs, which let the user evaluate some function f, but not create more programs for f? This paper tackles both questions using the arsenal of modern computational complexity. Our main result is that there exist quantum oracles relative to which publicly-verifiable quantum money is possible, and any family of functions that cannot be efficiently learned from its input-output behavior can be quantumly copy-protected. This provides the first formal evidence that these tasks are achievable. The technical core of our result is a "Complexity-Theoretic No-Cloning Theorem," which generalizes both the standard No-Cloning Theorem and the optimality of Grover search, and might be of independent interest. Our security argument also requires explicit constructions of quantum t-designs. Moving beyond the oracle world, we also present an explicit candidate scheme for publicly-verifiable quantum money, based on random stabilizer states; as well as two explicit schemes for copy-protecting the family of point functions. We do not know how to base the security of these schemes on any existing cryptographic assumption. (Note that without an oracle, we can only hope for security under some computational assumption.)

Scott Aaronson

2011-10-24T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Revealing Quantum Advantage in a Quantum Network  

E-Print Network [OSTI]

The assumption of source independence was used to reveal nonlocal (apart from standard Bell-CHSH scenario) nature of correlations generated in entanglement swapping experiments. In this work, we have derived a set of sufficient criteria, imposed on the states (produced by the sources) under which source independence can reveal nonbilocal nature of correlations in a quantum network. To show this, we have considered real two qubit X states thereby discussing the various utilities of assuming source independence in a quantum network.

Kaushiki Mukherjee; Biswajit Paul; Debasis Sarkar

2014-10-01T23:59:59.000Z

362

Quantum Copy-Protection and Quantum Money  

E-Print Network [OSTI]

Forty years ago, Wiesner proposed using quantum states to create money that is physically impossible to counterfeit, something that cannot be done in the classical world. However, Wiesner's scheme required a central bank to verify the money, and the question of whether there can be unclonable quantum money that anyone can verify has remained open since. One can also ask a related question, which seems to be new: can quantum states be used as copy-protected programs, which let the user evaluate some function f, but not create more programs for f? This paper tackles both questions using the arsenal of modern computational complexity. Our main result is that there exist quantum oracles relative to which publicly-verifiable quantum money is possible, and any family of functions that cannot be efficiently learned from its input-output behavior can be quantumly copy-protected. This provides the first formal evidence that these tasks are achievable. The technical core of our result is a "Complexity-Theoretic No-Clon...

Aaronson, Scott

2011-01-01T23:59:59.000Z

363

Quantum physics meets biology  

E-Print Network [OSTI]

Quantum physics and biology have long been regarded as unrelated disciplines, describing nature at the inanimate microlevel on the one hand and living species on the other hand. Over the last decades the life sciences have succeeded in providing ever more and refined explanations of macroscopic phenomena that were based on an improved understanding of molecular structures and mechanisms. Simultaneously, quantum physics, originally rooted in a world view of quantum coherences, entanglement and other non-classical effects, has been heading towards systems of increasing complexity. The present perspective article shall serve as a pedestrian guide to the growing interconnections between the two fields. We recapitulate the generic and sometimes unintuitive characteristics of quantum physics and point to a number of applications in the life sciences. We discuss our criteria for a future quantum biology, its current status, recent experimental progress and also the restrictions that nature imposes on bold extrapolations of quantum theory to macroscopic phenomena.

Markus Arndt; Thomas Juffmann; Vlatko Vedral

2009-11-01T23:59:59.000Z

364

Photonic quantum technologies  

E-Print Network [OSTI]

The first quantum technology, which harnesses uniquely quantum mechanical effects for its core operation, has arrived in the form of commercially available quantum key distribution systems that achieve enhanced security by encoding information in photons such that information gained by an eavesdropper can be detected. Anticipated future quantum technologies include large-scale secure networks, enhanced measurement and lithography, and quantum information processors, promising exponentially greater computation power for particular tasks. Photonics is destined for a central role in such technologies owing to the need for high-speed transmission and the outstanding low-noise properties of photons. These technologies may use single photons or quantum states of bright laser beams, or both, and will undoubtably apply and drive state-of-the-art developments in photonics.

Jeremy L. O'Brien; Akira Furusawa; Jelena Vu?kovi?

2010-03-20T23:59:59.000Z

365

Amplified Quantum Transforms  

E-Print Network [OSTI]

In this thesis we investigate two new Amplified Quantum Transforms. In particular we create and analyze the Amplified Quantum Fourier Transform (Amplified-QFT) and the Amplified-Haar Wavelet Transform. First, we provide a brief history of quantum mechanics and quantum computing. Second, we examine the Amplified-QFT in detail and compare it against the Quantum Fourier Transform (QFT) and Quantum Hidden Subgroup (QHS) algorithms for solving the Local Period Problem. We calculate the probabilities of success of each algorithm and show the Amplified-QFT is quadratically faster than the QFT and QHS algorithms. Third, we examine the Amplified-QFT algorithm for solving The Local Period Problem with an Error Stream. Fourth, we produce an uncertainty relation for the Amplified-QFT algorithm. Fifth, we show how the Amplified-Haar Wavelet Transform can solve the Local Constant or Balanced Signal Decision Problem which is a generalization of the Deutsch-Jozsa algorithm.

David Cornwell

2014-06-01T23:59:59.000Z

366

Underdamped quantum ratchets  

E-Print Network [OSTI]

We investigate the quantum ratchet effect under the influence of weak dissipation which we treat within a Floquet-Markov master equation approach. A ratchet current emerges when all relevant symmetries are violated. Using time-reversal symmetric driving we predict a purely dissipation-induced quantum ratchet current. This directed quantum transport results from bath-induced superpositions of non-transporting Floquet states.

S. Denisov; S. Kohler; P. Hanggi

2009-02-24T23:59:59.000Z

367

Quantum dense key distribution  

SciTech Connect (OSTI)

This paper proposes a protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than the Bennet-Brassard 1984 protocol. We hereinafter prove the security of this scheme against individual eavesdropping attacks, and we present preliminary experimental results, showing its feasibility.

Degiovanni, I.P.; Ruo Berchera, I.; Castelletto, S.; Rastello, M.L.; Bovino, F.A.; Colla, A.M.; Castagnoli, G. [Istituto Elettrotecnico Nazionale G. Ferraris, Strada delle Cacce 91, 10135 Torino (Italy); ELSAG SpA, Via Puccini 2, 16154, Genova (Italy)

2004-03-01T23:59:59.000Z

368

Motion in Quantum Gravity  

E-Print Network [OSTI]

We tackle the question of motion in Quantum Gravity: what does motion mean at the Planck scale? Although we are still far from a complete answer we consider here a toy model in which the problem can be formulated and resolved precisely. The setting of the toy model is three dimensional Euclidean gravity. Before studying the model in detail, we argue that Loop Quantum Gravity may provide a very useful approach when discussing the question of motion in Quantum Gravity.

Karim Noui

2010-03-31T23:59:59.000Z

369

Reducing Quantum Errors and Improving Large Scale Quantum Cryptography  

E-Print Network [OSTI]

Noise causes severe difficulties in implementing quantum computing and quantum cryptography. Several schemes have been suggested to reduce this problem, mainly focusing on quantum computation. Motivated by quantum cryptography, we suggest a coding which uses $N$ quantum bits ($N=n^2$) to encode one quantum bit, and reduces the error exponentially with $n$. Our result suggests the possibility of distributing a secure key over very long distances, and maintaining quantum states for very long times. It also provides a new quantum privacy amplification against a strong adversary.

T. Mor

1996-08-15T23:59:59.000Z

370

Scalar-quark systems and chimera hadrons in SU(3){sub c} lattice QCD  

SciTech Connect (OSTI)

In terms of mass generation in the strong interaction without chiral symmetry breaking, we perform the first study for light scalar-quarks {phi} (colored scalar particles with 3{sub c} or idealized diquarks) and their color-singlet hadronic states using quenched SU(3){sub c} lattice QCD with {beta}=5.70 (i.e., a{approx_equal}0.18 fm) and lattice size 16{sup 3}x32. We investigate ''scalar-quark mesons'' {phi}{sup {dagger}}{phi} and ''scalar-quark baryons'' {phi}{phi}{phi} as the bound states of scalar-quarks {phi}. We also investigate the color-singlet bound states of scalar-quarks {phi} and quarks {psi}, i.e., {phi}{sup {dagger}}{psi}, {psi}{psi}{phi}, and {phi}{phi}{psi}, which we name ''chimera hadrons.'' All the new-type hadrons including {phi} are found to have a large mass even for zero bare scalar-quark mass m{sub {phi}}=0 at a{sup -1}{approx_equal}1 GeV. We find a ''constituent scalar-quark/quark picture'' for both scalar-quark hadrons and chimera hadrons. Namely, the mass of the new-type hadron composed of m {phi}'s and n {psi}'s, M{sub m{phi}}{sub +n{psi}}, approximately satisfies M{sub m{phi}}{sub +n{psi}}{approx_equal}mM{sub {phi}}+nM{sub {psi}}, where M{sub {phi}} and M{sub {psi}} are the constituent scalar-quark and quark masses, respectively. We estimate the constituent scalar-quark mass M{sub {phi}} for m{sub {phi}}=0 at a{sup -1}{approx_equal}1 GeV as M{sub {phi}}{approx_equal}1.5-1.6 GeV, which is much larger than the constituent quark mass M{sub {psi}}{approx_equal}400 MeV in the chiral limit. Thus, scalar quarks acquire a large mass due to large quantum corrections by gluons in the systems including scalar quarks. Together with other evidences of mass generation of glueballs and charmonia, we conjecture that all colored particles generally acquire a large effective mass due to dressed gluon effects. In addition, the large mass generation of pointlike colored scalar particles indicates that plausible diquarks used in effective hadron models cannot be described as the pointlike particles and should have a much larger size than a{approx_equal}0.2 fm.

Iida, H.; Takahashi, T. T. [Yukawa Institute for Theoretical Physics, Kyoto University, Sakyo, Kyoto 606-8502 (Japan); Suganuma, H. [Department of Physics, Kyoto University, Graduate School of Science, Sakyo, Kyoto 606-8502 (Japan)

2007-06-01T23:59:59.000Z

371

Coherent control of quantum information  

E-Print Network [OSTI]

Quantum computation requires the ability to efficiently control quantum information in the presence of noise. In this thesis, NMR quantum information processors (QIPs) are used to study noise processes that compromise ...

Henry, Michael Kevin

2006-01-01T23:59:59.000Z

372

Quantum Money with Classical Verification  

E-Print Network [OSTI]

We construct a quantum money scheme that allows verification through classical communication with bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification.

Gavinsky, Dmitry

2011-01-01T23:59:59.000Z

373

QUANTUM CONVERSION IN PHOTOSYNTHESIS  

E-Print Network [OSTI]

QUANTUM CONVERSION IN PHOTOSYNTHESIS Melvin Calvin Januaryas it occurs in modern photosynthesis can only take place inof the problem or photosynthesis, or any specific aspect of

Calvin, Melvin

2008-01-01T23:59:59.000Z

374

Rotational Quantum Friction  

E-Print Network [OSTI]

We investigate the frictional forces due to quantum fluctuations acting on a small sphere rotating near a surface. At zero temperature, we find the frictional force near a surface to be several orders of magnitude larger than that for the sphere rotating in vacuum. For metallic materials with typical conductivity, quantum friction is maximized by matching the frequency of rotation with the conductivity. Materials with poor conductivity are favored to obtain large quantum frictions. For semiconductor materials that are able to support surface plasmon polaritons, quantum friction can be further enhanced by several orders of magnitude due to the excitation of surface plasmon polaritons.

Rongkuo Zhao; Alejandro Manjavacas; F. Javier García de Abajo; J. B. Pendry

2012-08-21T23:59:59.000Z

375

Classical and Quantum Polyhedra  

E-Print Network [OSTI]

Quantum polyhedra constructed from angular momentum operators are the building blocks of space in its quantum description as advocated by Loop Quantum Gravity. Here we extend previous results on the semiclassical properties of quantum polyhedra. Regarding tetrahedra, we compare the results from a canonical quantization of the classical system with a recent wave function based approach to the large-volume sector of the quantum system. Both methods agree in the leading order of the resulting effective operator (given by an harmonic oscillator), while minor differences occur in higher corrections. Perturbative inclusion of such corrections improves the approximation to the eigenstates. Moreover, the comparison of both methods leads also to a full wave function description of the eigenstates of the (square of the) volume operator at negative eigenvalues of large modulus. For the case of general quantum polyhedra described by discrete angular momentum quantum numbers we formulate a set of quantum operators fulfilling in the semiclassical regime the standard commutation relations between momentum and position. Differently from previous formulations, the position variable here is chosen to have dimension of (Planck) length squared which facilitates the identification of quantum corrections. Finally, we provide expressions for the pentahedral volume in terms of Kapovich-Millson variables.

John Schliemann

2014-12-11T23:59:59.000Z

376

Superradiant Quantum Heat Engine  

E-Print Network [OSTI]

Quantum physics has revolutionized the classical disciplines of mechanics, statistical physics, and electrodynamics. It modernized our society with many advances such as lasers and transistors. One branch of scientific knowledge however seems untouched: thermodynamics. Major motivation behind thermodynamics is to develop efficient heat engines. Technology has a trend to miniaturize engines, reaching to the quantum regimes. Inevitably, development of quantum heat engines (QHEs) requires investigations of thermodynamical principles from quantum mechanical perspective, and motivates the emerging field of quantum thermodynamics. Studies of QHEs debate on whether quantum coherence can be used as a resource. We explore an alternative that quantum coherence can be a catalyst. We propose a QHE which consists of a photon gas inside an optical cavity as the working fluid and quantum coherent atomic clusters as the fuel. Utilizing the superradiance, where a cluster can radiate quadratically faster than a single atom, we show that the work capability of the QHE becomes proportional to the square of the number of the atoms. In addition to practical value of cranking up a QHE, our results reveal a fundamental difference of a quantum fuel from its classical counterpart.

Ali Ü. C. Hardal; Özgür E. Müstecapl?oglu

2015-03-12T23:59:59.000Z

377

Quantum spin dynamics  

E-Print Network [OSTI]

The classical Landau-Lifshitz equation has been derived from quantum mechanics. Starting point is the assumption of a non-Hermitian Hamilton operator to take the energy dissipation into account. The corresponding quantum mechanical time dependent Schr\\"odinger, Liouville and Heisenberg equation have been described and the similarities and differences between classical and quantum mechanical spin dynamics have been discussed. Furthermore, a time dependent Schr\\"odinger equation corresponding to the classical Landau-Lifshitz-Gilbert equation and two ways to include temperature into the quantum mechanical spin dynamics have been proposed.

Robert Wieser

2014-10-23T23:59:59.000Z

378

Quantum Field Theory & Gravity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email...

379

Quantum Haplodynamics, Dark Matter and Dark Energy  

E-Print Network [OSTI]

In quantum haplodynamics (QHD) the weak bosons, quarks and leptons are bound states of fundamental constituents, denoted as haplons. The confinement scale of the associated gauge group SU(2)_h is of the order of $\\Lambda_h\\simeq 0.3$ TeV. One scalar state has zero haplon number and is the resonance observed at the LHC. In addition, there exist new bound states of haplons with no counterpart in the SM, having a mass of the order of 0.5 TeV up to a few TeV. In particular, a neutral scalar state with haplon number 4 is stable and can provide the dark matter in the universe. The QHD, QCD and QED couplings can unify at the Planck scale. If this scale changes slowly with cosmic time, all of the fundamental couplings, the masses of the nucleons and of the DM particles, including the cosmological term (or vacuum energy density), will evolve with time. This could explain the dark energy of the universe.

Harald Fritzsch; Joan Sola

2014-08-04T23:59:59.000Z

380

Light Quarkonium - Glueball Mixing from a Holographic QCD  

E-Print Network [OSTI]

We study the mixing structure of isospin-singlet scalars, the light quarkonium $(\\bar{q}q)$ and glueball $(gg)$ in two-flavor QCD, based on a holographic model of bottom-up hard-wall type. In the model the pure quarkonium and glueball states are unambiguously defined in terms of the different $U(1)_A$ charges in the restoration limit of the chiral $U(2)_L \\times U(2)_R$ symmetry, in which the quarkonium gets massless as the chiral partner of the pion. Hence the $\\bar{q}q$-$gg$ mixing arises in the presence of the nonzero chiral condensate or pion decay constant. At the realistic point where the pion decay constant and other hadron masses reach the observed amount, we predict the tiny mixing between the lightest quarkonia and glueball: The smallness of the mixing is understood by the slightly small ratio of the chiral and gluon condensate scales. The low-lying two scalar masses are calculated to be $\\simeq 1.25$ GeV and $\\simeq 1.77$ GeV, which are compared with masses of $f_0(1370)$ and $f_0(1710)$. Our resul...

Yamaguchi, Takashi

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Complex saddle points in QCD at finite temperature and density  

E-Print Network [OSTI]

The sign problem in QCD at finite temperature and density leads naturally to the consideration of complex saddle points of the action or effective action. The global symmetry $\\mathcal{CK}$ of the finite-density action, where $\\mathcal{C}$ is charge conjugation and $\\mathcal{K}$ is complex conjugation, constrains the eigenvalues of the Polyakov loop operator $P$ at a saddle point in such a way that the action is real at a saddle point, and net color charge is zero. The values of $Tr_{F}P$ and $Tr_{F}P^{\\dagger}$ at the saddle point, are real but not identical, indicating the different free energy cost associated with inserting a heavy quark versus an antiquark into the system. At such complex saddle points, the mass matrix associated with Polyakov loops may have complex eigenvalues, reflecting oscillatory behavior in color-charge densities. We illustrate these properties with a simple model which includes the one-loop contribution of gluons and massless quarks moving in a constant Polyakov loop background. Confinement-deconfinement effects are modeled phenomenologically via an added potential term depending on the Polyakov loop eigenvalues. For sufficiently large $T$ and $\\mu$, the results obtained reduce to those of perturbation theory at the complex saddle point. These results may be experimentally relevant for the CBM experiment at FAIR.

Hiromichi Nishimura; Michael C. Ogilvie; Kamal Pangeni

2014-08-12T23:59:59.000Z

382

A test of first order scaling in Nf=2 QCD  

E-Print Network [OSTI]

We complete our analysis of Nf=2 QCD based on the lattice staggered fermion formulation. Using a series of Monte Carlo simulations at fixed (amq*Ls^yh) one is able to test the universality class with given critical exponent yh. This strategy has been used to test the O(4) universality class and it has been presented at the previous Lattice conferences. No agreement was found with simulations in the mass range amq=[0.01335,0.15] using lattices with Ls=16 up to 32 and Lt=4. With the same strategy, we now investigate the possibility of a first order transition using a new set of Monte Carlo data corresponding to yh=3 in the same mass and volume range as the one used for O(4). A substantial agreement is observed both in the specific heat scaling and in the scaling of the chiral condensate, while the chiral susceptibilities still presents visible deviation from scaling in the mass range explored.

G. Cossu; M. D'Elia; A. Di Giacomo; C. Pica

2007-09-30T23:59:59.000Z

383

Multiquark Correlations in Light Mesons and Baryons from holographic QCD  

SciTech Connect (OSTI)

A hadron's multiquark content reflects itself in the quark composition of the interpolator with which it has maximal overlap. The AdS/CFT dictionary translates the anomalous dimension of this interpolator into a mass correction for the corresponding dual mode. Hence such bulk-mass corrections can carry specific information on multiquark correlations. Two prominent examples are studied by implementing this robust and universal holographic mechanism into AdS/QCD gravity duals. In the baryon sector bulk-mass corrections are used to describe systematic good (i.e. maximally attractive) diquark effects. The baryon sizes are predicted to decrease with increasing good-diquark content, and the masses of all 48 observed light-quark baryon states are reproduced with unprecedented accuracy. Our approach further provides the first holographic description of a dominant tetraquark component in the lowest-lying scalar mesons. The tetraquark ground state emerges naturally as the lightest scalar nonet whereas higher excitations become heavier than their quark--antiquark counterparts and are thus likely to dissolve into the multiparticle continuum.

Forkel, Hilmar [Institut fuer Physik, Humboldt-Universitaet zu Berlin, D-12489 Berlin (Germany)

2011-10-21T23:59:59.000Z

384

Study of the $Z_c^+$ channel using lattice QCD  

E-Print Network [OSTI]

Recently experimentalists have discovered several charged charmonium-like hadrons $Z_c^+$ with unconventional quark content $\\bar cc\\bar d u$. We perform a search for $Z_c^+$ with mass below $4.2~$GeV in the channel $I^G(J^{PC})=1^+(1^{+-})$ using lattice QCD. The major challenge is presented by the two-meson states $J/\\psi\\, \\pi$, $\\psi_{2S}\\pi$, $\\psi_{1D}\\pi$, $D\\bar D^*$, $D^*\\bar D^*$, $\\eta_c\\rho$ that are inevitably present in this channel. The spectrum of eigenstates is extracted using a number of meson-meson and diquark-antidiquark interpolating fields. For our pion mass of 266~MeV we find all the expected two-meson states but no additional candidate for $Z_c^+$ below $4.2~$GeV. Possible reasons for not seeing an additional eigenstate related to $Z_c^+$ are discussed. We also illustrate how a simulation incorporating interpolators with a structure resembling low-lying two-mesons states seems to render a $Z_c^+$ candidate, which is however not robust after further two-meson states around $4.2~$GeV are implemented.

Sasa Prelovsek; C. B. Lang; Luka Leskovec; Daniel Mohler

2015-01-20T23:59:59.000Z

385

Topological Structure of the QCD Vacuum Revealed by Overlap Fermions  

E-Print Network [OSTI]

Overlap fermions preserve a remnant of chiral symmetry on the lattice. They are a powerful tool to investigate the topological structure of the vacuum of Yang-Mills theory and full QCD. Recent results concerning the localization of topological charge and the localization and local chirality of the overlap eigenmodes are reported. The charge distribution is radically different, if a spectral cut-off for the Dirac eigenmodes is applied. The density q(x) is changing from the scale-a charge density (with full lattice resolution) to the ultraviolet filtered charge density. The scale-a density, computed on the Linux cluster of LRZ, has a singular, sign-coherent global structure of co-dimension 1 first described by the Kentucky group. We stress, however, the cluster properties of the UV filtered topological density resembling the instanton picture. The spectral cut-off can be mapped to a bosonic smearing procedure. The UV filtered field strength reveals a high degree of (anti)selfduality at "hot spots" of the action. The fermionic eigenmodes show a high degree of local chirality. The lowest modes are seen to be localized in low-dimensional space-time regions.

E. -M. Ilgenfritz; K. Koller; Y. Koma; G. Schierholz; V. Weinberg

2010-03-15T23:59:59.000Z

386

Calculation of Helium nuclei in quenched lattice QCD  

E-Print Network [OSTI]

We present results for the binding energies for ^4He and ^3He nuclei calculated in quenched lattice QCD at the lattice spacing of a =0.128 fm with a heavy quark mass corresponding to m_pi = 0.8 GeV. Enormous computational cost for the nucleus correlation functions is reduced by avoiding redundancy of equivalent contractions stemming from permutation symmetry of protons or neutrons in the nucleus and various other symmetries. To distinguish a bound state from an attractive scattering state, we investigate the volume dependence of the energy difference between the ground state energy of the nucleus channel and the free multi-nucleon states by changing the spatial extent of the lattice from 3.1 fm to 12.3 fm. A finite energy difference left in the infinite spatial volume limit leads to the conclusion that the measured ground states are bounded. It is also encouraging that the measured binding energies and the experimental ones show the same order of magnitude.

T. Yamazaki

2010-12-02T23:59:59.000Z

387

Some foundational aspects of quantum computers and quantum robots.  

SciTech Connect (OSTI)

This paper addresses foundational issues related to quantum computing. The need for a universally valid theory such as quantum mechanics to describe to some extent its own validation is noted. This includes quantum mechanical descriptions of systems that do theoretical calculations (i.e. quantum computers) and systems that perform experiments. Quantum robots interacting with an environment are a small first step in this direction. Quantum robots are described here as mobile quantum systems with on-board quantum computers that interact with environments. Included are discussions on the carrying out of tasks and the division of tasks into computation and action phases. Specific models based on quantum Turing machines are described. Differences and similarities between quantum robots plus environments and quantum computers are discussed.

Benioff, P.; Physics

1998-01-01T23:59:59.000Z

388

The Quantum Frontier  

E-Print Network [OSTI]

The success of the abstract model of computation, in terms of bits, logical operations, programming language constructs, and the like, makes it easy to forget that computation is a physical process. Our cherished notions of computation and information are grounded in classical mechanics, but the physics underlying our world is quantum. In the early 80s researchers began to ask how computation would change if we adopted a quantum mechanical, instead of a classical mechanical, view of computation. Slowly, a new picture of computation arose, one that gave rise to a variety of faster algorithms, novel cryptographic mechanisms, and alternative methods of communication. Small quantum information processing devices have been built, and efforts are underway to build larger ones. Even apart from the existence of these devices, the quantum view on information processing has provided significant insight into the nature of computation and information, and a deeper understanding of the physics of our universe and its connections with computation. We start by describing aspects of quantum mechanics that are at the heart of a quantum view of information processing. We give our own idiosyncratic view of a number of these topics in the hopes of correcting common misconceptions and highlighting aspects that are often overlooked. A number of the phenomena described were initially viewed as oddities of quantum mechanics. It was quantum information processing, first quantum cryptography and then, more dramatically, quantum computing, that turned the tables and showed that these oddities could be put to practical effect. It is these application we describe next. We conclude with a section describing some of the many questions left for future work, especially the mysteries surrounding where the power of quantum information ultimately comes from.

Joseph F. Fitzsimons; Eleanor G. Rieffel; Valerio Scarani

2013-06-16T23:59:59.000Z

389

Collective String Interactions in AdS/QCD and High-Multiplicity pA Collisions  

E-Print Network [OSTI]

QCD strings originate from high-energy scattering in the form of Reggions and Pomerons, and have been studied in some detail in lattice numerical simulations. Production of multiple strings, with their subsequent breaking, is now a mainstream model of high energy $pp$ and $pA$ collisions. Recent LHC experiments revealed that high multiplicity end of such collisions show interesting collective effects. This ignited an interest in the interaction of QCD strings and multi-string dynamics. Holographic models, collectively known as AdS/QCD, developed in the last decade, describe both hadronic spectroscopy and basic thermodynamics, but so far no studies of the QCD strings have been done in this context. The subject of this paper is to do this. First, we study in more detail the scalar sector of hadronic spectroscopy, identifying "glueballs" and "scalar mesons," and calculate the degree of their mixing. The QCD strings, holographic images of the fundamental strings, thus have a "gluonic core" and a "sigma cloud." Th...

Iatrakis, Ioannis; Shuryak, Edward

2015-01-01T23:59:59.000Z

390

Quantum Physics Einstein's Gravity  

E-Print Network [OSTI]

Quantum Physics confronts Einstein's Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 13 October 2001 #12; Quantum Physics confronts Einstein's Gravity and with Einstein's theory of gravity (the general relativity) is still the single biggest theoretical problem

Visser, Matt

391

Quantum Gravity and Turbulence  

E-Print Network [OSTI]

We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.

Vishnu Jejjala; Djordje Minic; Y. Jack Ng; Chia-Hsiung Tze

2010-05-18T23:59:59.000Z

392

Quantum Spacetime Phenomenology  

E-Print Network [OSTI]

I review the current status of phenomenological programs inspired by quantum-spacetime research. I stress in particular the significance of results establishing that certain data analyses provide sensitivity to effects introduced genuinely at the Planck scale. And my main focus is on phenomenological programs that managed to affect the directions taken by studies of quantum-spacetime theories.

Giovanni Amelino-Camelia

2013-06-18T23:59:59.000Z

393

Thermalization in Quantum Systems  

E-Print Network [OSTI]

of equilibrated states. iv. Definition for "quantum integrability". v. Many-body localization... vi. Open systems () 0 = ||2 . ETH: is approximately constant in the "energy window" of the state . ETH: For all 10 #12;Integrability 101 Quantum Integrability Classical systems: Definition: A system is integrable

394

Quantum Simulations of Lattice Gauge Theories using Ultracold Atoms in Optical Lattices  

E-Print Network [OSTI]

Can high energy physics can be simulated by low-energy, nonrelativistic, many-body systems, such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in particular, they manifest neither local gauge invariance nor Lorentz invariance, which are crucial properties of the quantum field theories which are the building blocks of the standard model of elementary particles. However, it turns out, surprisingly, that there are ways to configure atomic system to manifest both local gauge invariance and Lorentz invariance. In particular, local gauge invariance can arise either as an effective, low energy, symmetry, or as an "exact" symmetry, following from the conservation laws in atomic interactions. Hence, one could hope that such quantum simulators may lead to new type of (table-top) experiments, that shall be used to study various QCD phenomena, as the con?nement of dynamical quarks, phase transitions, and other effects, which are inacc...

Zohar, Erez; Reznik, Benni

2015-01-01T23:59:59.000Z

395

Quantum-noise quenching in quantum tweezers  

E-Print Network [OSTI]

The efficiency of extracting single atoms or molecules from an ultracold bosonic reservoir is theoretically investigated for a protocol based on lasers, coupling the hyperfine state in which the atoms form a condensate to another stable state, in which the atom experiences a tight potential in the regime of collisional blockade, the quantum tweezers. The transfer efficiency into the single-atom ground state of the tight trap is fundamentally limited by the collective modes of the condensate, which are thermally and dynamically excited and constitute the ultimate noise sources. This quantum noise can be quenched for sufficiently long laser pulses, thereby achieving high efficiencies, and showing that this protocol can be applied for quantum information processing based on tweezer traps for neutral atoms.

Zippilli, Stefano; Lutz, Eric; Morigi, Giovanna; Schleich, Wolfgang

2010-01-01T23:59:59.000Z

396

High Performance Quantum Computing  

E-Print Network [OSTI]

The architecture scalability afforded by recent proposals of a large scale photonic based quantum computer, utilizing the theoretical developments of topological cluster states and the photonic chip, allows us to move on to a discussion of massively scaled Quantum Information Processing (QIP). In this letter we introduce the model for a secure and unsecured topological cluster mainframe. We consider the quantum analogue of High Performance Computing, where a dedicated server farm is utilized by many users to run algorithms and share quantum data. The scaling structure of photonics based topological cluster computing leads to an attractive future for server based QIP, where dedicated mainframes can be constructed and/or expanded to serve an increasingly hungry user base with the ideal resource for individual quantum information processing.

Simon J. Devitt; William J. Munro; Kae Nemoto

2008-10-14T23:59:59.000Z

397

Permutational Quantum Computing  

E-Print Network [OSTI]

In topological quantum computation the geometric details of a particle trajectory are irrelevant; only the topology matters. Taking this one step further, we consider a model of computation that disregards even the topology of the particle trajectory, and computes by permuting particles. Whereas topological quantum computation requires anyons, permutational quantum computation can be performed with ordinary spin-1/2 particles, using a variant of the spin-network scheme of Marzuoli and Rasetti. We do not know whether permutational computation is universal. It may represent a new complexity class within BQP. Nevertheless, permutational quantum computers can in polynomial time approximate matrix elements of certain irreducible representations of the symmetric group and simulate certain processes in the Ponzano-Regge spin foam model of quantum gravity. No polynomial time classical algorithms for these problems are known.

Stephen P. Jordan

2009-06-14T23:59:59.000Z

398

Universal blind quantum computation  

E-Print Network [OSTI]

We present a protocol which allows a client to have a server carry out a quantum computation for her such that the client's inputs, outputs and computation remain perfectly private, and where she does not require any quantum computational power or memory. The client only needs to be able to prepare single qubits randomly chosen from a finite set and send them to the server, who has the balance of the required quantum computational resources. Our protocol is interactive: after the initial preparation of quantum states, the client and server use two-way classical communication which enables the client to drive the computation, giving single-qubit measurement instructions to the server, depending on previous measurement outcomes. Our protocol works for inputs and outputs that are either classical or quantum. We give an authentication protocol that allows the client to detect an interfering server; our scheme can also be made fault-tolerant. We also generalize our result to the setting of a purely classical client who communicates classically with two non-communicating entangled servers, in order to perform a blind quantum computation. By incorporating the authentication protocol, we show that any problem in BQP has an entangled two-prover interactive proof with a purely classical verifier. Our protocol is the first universal scheme which detects a cheating server, as well as the first protocol which does not require any quantum computation whatsoever on the client's side. The novelty of our approach is in using the unique features of measurement-based quantum computing which allows us to clearly distinguish between the quantum and classical aspects of a quantum computation.

Anne Broadbent; Joseph Fitzsimons; Elham Kashefi

2009-12-12T23:59:59.000Z

399

Continuous-variable quantum-state sharing via quantum disentanglement  

SciTech Connect (OSTI)

Quantum-state sharing is a protocol where perfect reconstruction of quantum states is achieved with incomplete or partial information in a multipartite quantum network. Quantum-state sharing allows for secure communication in a quantum network where partial information is lost or acquired by malicious parties. This protocol utilizes entanglement for the secret-state distribution and a class of 'quantum disentangling' protocols for the state reconstruction. We demonstrate a quantum-state sharing protocol in which a tripartite entangled state is used to encode and distribute a secret state to three players. Any two of these players can collaborate to reconstruct the secret state, while individual players obtain no information. We investigate a number of quantum disentangling processes and experimentally demonstrate quantum-state reconstruction using two of these protocols. We experimentally measure a fidelity, averaged over all reconstruction permutations, of F=0.73{+-}0.02. A result achievable only by using quantum resources.

Lance, Andrew M.; Symul, Thomas; Lam, Ping Koy [Quantum Optics Group, Department of Physics, Faculty of Science, Australian National University, ACT 0200 (Australia); Bowen, Warwick P. [Quantum Optics Group, Department of Physics, Faculty of Science, Australian National University, ACT 0200 (Australia); Quantum Optics Group, Norman Bridge Laboratory of Physics, California Institute of Technology, Pasadena, California 91125 (United States); Sanders, Barry C. [Institute for Quantum Information Science, University of Calgary, Alberta T2N 1N4 (Canada); Tyc, Tomas [Institute of Theoretical Physics, Masaryk University, 61137 Brno (Czech Republic); Ralph, T.C. [Department of Physics, University of Queensland, St. Lucia QLD 4072 (Australia)

2005-03-01T23:59:59.000Z

400

Lattice QCD-based equations of state at vanishing net-baryon density  

E-Print Network [OSTI]

We present realistic equations of state for QCD matter at vanishing net-baryon density which embed recent lattice QCD results at high temperatures combined with a hadron resonance gas model in the low-temperature, confined phase. In the latter, we allow an implementation of partial chemical equilibrium, in which particle ratios are fixed at the chemical freeze-out, so that a description closer to the experimental situation is possible. Given the present uncertainty in the determination of the chemical freeze-out temperature from first-principle lattice QCD calculations, we consider different values within the expected range. The corresponding equations of state can be applied in the hydrodynamic modeling of relativistic heavy-ion collisions at the LHC and at the highest RHIC beam energies. Suitable parametrizations of our results as functions of the energy density are also provided.

M. Bluhm; P. Alba; W. Alberico; A. Beraudo; C. Ratti

2014-07-16T23:59:59.000Z

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401

Present Constraints on the H-dibaryon at the Physical Point from Lattice QCD  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

The current constraints from Lattice QCD on the existence of the H-dibaryon are discussed. With only two significant Lattice QCD calculations of the H-dibaryon binding energy at approximately the same lattice spacing, the form of the chiral and continuum extrapolations to the physical point are not determined. In this brief report, an extrapolation that is quadratic in the pion mass, motivated by low-energy effective field theory, is considered. An extrapolation that is linear in the pion mass is also considered, a form that has no basis in the effective field theory, but is found to describe the light-quark mass dependence observed in Lattice QCD calculations of the octet baryon masses. In both instances, the extrapolation to the physical pion mass allows for a bound H-dibaryon or a near-threshold scattering state.

Beane, Silas; Detmold, Will; Joo, Balint; Lin, Huey-Wen; Luu, T C; Orginos, Konstantinos; Parreno, Assumpta; Savage, Martin; Torok, Aaron

2011-11-10T23:59:59.000Z

402

The Nc dependencies of baryon masses: Analysis with Lattice QCD and Effective Theory  

E-Print Network [OSTI]

Baryon masses at varying values of Nc and light quark masses are studied with Lattice QCD and the results are analyzed in a low energy effective theory based on a combined framework of the 1/Nc and Heavy Baryon Chiral Perturbation Theory expansions. Lattice QCD results for Nc = 3, 5 and 7 obtained in quenched calculations, as well as results for unquenched calculations for Nc = 3, are used for the analysis. The results are consistent with a previous analysis of Nc = 3 Lattice QCD results, and in addition permit the determination of sub-leading in 1/Nc effects in the spin-flavor singlet component of the baryon masses as well as in the hyperfine splittings.

A. Calle Cordon; T. DeGrand; J. L. Goity

2014-04-08T23:59:59.000Z

403

Spatial distributions in static heavy-light mesons: a comparison of quark models with lattice QCD  

E-Print Network [OSTI]

Lattice measurements of spatial distributions of the light quark bilinear densities in static mesons allow to test directly and in detail the wave functions of quark models. These distributions are gauge invariant quantities directly related to the spatial distribution of wave functions. We make a detailed comparison of the recent lattice QCD results with our own quark models, formulated previously for quite different purposes. We find a striking agreement not only between our two quark models, but also with the lattice QCD data for the ground state in an important range of distances up to about 4/GeV. Moreover the agreement extends to the L=1 states [j^P=(1/2)^+]. An explanation of several particular features completely at odds with the non-relativistic approximation is provided. A rather direct, somewhat unexpected and of course approximate relation between wave functions of certain quark models and QCD has been established.

Damir Becirevic; Emmanuel Chang; Alain Le Yaouanc Luis Oliver; Jean-Claude Raynal

2011-09-19T23:59:59.000Z

404

Spectral function and excited states in lattice QCD with maximum entropy method  

E-Print Network [OSTI]

We apply the maximum entropy method to extract the spectral functions for pseudoscalar and vector mesons from hadron correlators previously calculated at four different lattice spacings in quenched QCD with the Wilson quark action. We determine masses and decay constants for the ground and excited states of the pseudoscalar and vector channels from position and area of peaks in the spectral functions. We obtain the results, $m_{\\pi_1} = 660(590)$ MeV and $m_{\\rho_1} = 1540(570)$ MeV for the masses of the first excited state masses, in the continuum limit of quenched QCD. We also find unphysical states which have infinite mass in the continuum limit, and argue that they are bound states of two doublers of the Wilson quark action. If the interpretation is correct, this is the first time that the state of doublers is identified in lattice QCD numerical simulations.

CP-PACS Collaboration; :; T. Yamazaki; S. Aoki; R. Burkhalter; M. Fukugita; S. Hashimoto; N. Ishizuka; Y. Iwasaki; K. Kanaya; T. Kaneko; Y. Kuramashi; M. Okawa; Y. Taniguchi; A. Ukawa; T. Yoshié

2001-05-29T23:59:59.000Z

405

Quantum Computing, Metrology, and Imaging  

E-Print Network [OSTI]

Information science is entering into a new era in which certain subtleties of quantum mechanics enables large enhancements in computational efficiency and communication security. Naturally, precise control of quantum systems required for the implementation of quantum information processing protocols implies potential breakthoughs in other sciences and technologies. We discuss recent developments in quantum control in optical systems and their applications in metrology and imaging.

Hwang Lee; Pavel Lougovski; Jonathan P. Dowling

2005-06-17T23:59:59.000Z

406

Nonlinear friction in quantum mechanics  

E-Print Network [OSTI]

The effect of nonlinear friction forces in quantum mechanics is studied via dissipative Madelung hydrodynamics. A new thermo-quantum diffusion equation is derived, which is solved for the particular case of quantum Brownian motion with a cubic friction. It is extended also by a chemical reaction term to describe quantum reaction-diffusion systems with nonlinear friction as well.

Roumen Tsekov

2010-03-01T23:59:59.000Z

407

AN INTRODUCTION TO QUANTUM OPTICS...  

E-Print Network [OSTI]

AN INTRODUCTION TO QUANTUM OPTICS... ...the light as you've never seen before... Optics:http://science.howstuffworks.com/laser5.htm #12;5 DEFINITION Quantum Optics: "Quantum optics is a field in quantum physics, dealing OPTICS OPERATORS Light is described in terms of field operators for creation and annihilation of photons

Palffy-Muhoray, Peter

408

Magmatic "Quantum-Like" Systems  

E-Print Network [OSTI]

Quantum computation has suggested, among others, the consideration of "non-quantum" systems which in certain respects may behave "quantum-like". Here, what algebraically appears to be the most general possible known setup, namely, of {\\it magmas} is used in order to construct "quantum-like" systems. The resulting magmatic composition of systems has as a well known particular case the tensor products.

Elemer E Rosinger

2008-12-16T23:59:59.000Z

409

DOE Announces $60 Million in Projects to Accelerate Scientific...  

Energy Savers [EERE]

areas will complement research in fusion energy, global climate, turbulence, stress corrosion cracking, computational chemistry and quantum chromodynamics. In support of these...

410

alpha supports tumor: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

momentum. The 2-jet cross section is also measured as a function of the proton momentum fraction xi. The measurements are well described by perturbative quantum chromodynamics at...

411

Layered architecture for quantum computing  

E-Print Network [OSTI]

We develop a layered quantum computer architecture, which is a systematic framework for tackling the individual challenges of developing a quantum computer while constructing a cohesive device design. We discuss many of the prominent techniques for implementing circuit-model quantum computing and introduce several new methods, with an emphasis on employing surface code quantum error correction. In doing so, we propose a new quantum computer architecture based on optical control of quantum dots. The timescales of physical hardware operations and logical, error-corrected quantum gates differ by several orders of magnitude. By dividing functionality into layers, we can design and analyze subsystems independently, demonstrating the value of our layered architectural approach. Using this concrete hardware platform, we provide resource analysis for executing fault-tolerant quantum algorithms for integer factoring and quantum simulation, finding that the quantum dot architecture we study could solve such problems on the timescale of days.

N. Cody Jones; Rodney Van Meter; Austin G. Fowler; Peter L. McMahon; Jungsang Kim; Thaddeus D. Ladd; Yoshihisa Yamamoto

2012-09-27T23:59:59.000Z

412

Constraints on spin-dependent parton distributions at large x from global QCD analysis  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We investigate the behavior of spin-dependent parton distribution functions (PDFs) at large parton momentum fractions x in the context of global QCD analysis. We explore the constraints from existing deep-inelastic scattering data, and from theoretical expectations for the leading x -> 1 behavior based on hard gluon exchange in perturbative QCD. Systematic uncertainties from the dependence of the PDFs on the choice of parametrization are studied by considering functional forms motivated by orbital angular momentum arguments. Finally, we quantify the reduction in the PDF uncertainties that may be expected from future high-x data from Jefferson Lab at 12 GeV.

Jimenez-Delgado, Pedro [JLAB; Avakian, Harut A. [JLAB; Melnitchouk, Wally [JLAB

2014-11-01T23:59:59.000Z

413

Infrared and Ultraviolet QCD dynamics with quark mass for J=0,1 mesons  

E-Print Network [OSTI]

By using a previously developed phenomenological kernel for the study of the light quark QCD sector and dynamical chiral symmetry breaking effects we will examine the relative infrared and ultraviolet QCD dynamics for J=0,1 meson properties. For the same reasons we extend and explore a quark mass depended generalization of the kernel in the heavy quark region and we also compare with the original model. The relation between the dynamics of the quark propagator and the effective kernel with the J=0,1 QQ and qQ mesons and quarks Compton size is also discussed.

Nicholas Souchlas

2010-06-04T23:59:59.000Z

414

SPIN Effects, QCD, and Jefferson Laboratory with 12 GeV electrons  

SciTech Connect (OSTI)

QCD and Spin physics are playing important role in our understanding of hadron structure. I will give a short overview of origin of hadron structure in QCD and highlight modern understanding of the subject. Jefferson Laboratory is undergoing an upgrade that will increase the energy of electron beam up to 12 GeV. JLab is one of the leading facilities in nuclear physics studies and once operational in 2015 JLab 12 will be crucial for future of nuclear physics. I will briefly discuss future studies in four experimental halls of Jefferson Lab.

Prokudin, Alexey [JLAB

2013-11-01T23:59:59.000Z

415

Has the QCD Critical Point Been Signaled by Observations at the BNL Relativistic Heavy Ion Collider?  

SciTech Connect (OSTI)

The shear viscosity to entropy ratio ({eta}/s) is estimated for the hot and dense QCD matter created in Au+Au collisions at BNL Relativistic Heavy Ion Collider ({radical}(s{sub NN})=200 GeV). A very low value is found; {eta}/s{approx}0.1, which is close to the conjectured lower bound (1/4{pi}). It is argued that such a low value is indicative of thermodynamic trajectories for the decaying matter which lie close to the QCD critical end point.

Lacey, Roy A.; Ajitanand, N. N.; Alexander, J. M.; Chung, P.; Holzmann, W. G.; Issah, M.; Taranenko, A. [Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400 (United States); Danielewicz, P. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Stoecker, Horst [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet D60438 Frankfurt (Germany)

2007-03-02T23:59:59.000Z

416

Has the QCD Critical Point been Signaled by Observations at RHIC ?  

E-Print Network [OSTI]

The shear viscosity to entropy ratio ($\\eta/s$) is estimated for the hot and dense QCD matter created in Au+Au collisions at RHIC ($\\sqrt{s_{NN}}=200$ GeV). A very low value is found $\\eta/s \\sim 0.1$, which is close to the absolute lower bound ($1/4\\pi$). It is argued that such a low value is indicative of thermodynamic trajectories for the decaying matter which lie close to the QCD critical end point.

Lacey, R A; Alexander, J M; Chung, P; Danielewicz, P; Holzmann, W G; Issah, M; Stöcker, H; Taranenko, A; Lacey, Roy A.; Stocker, Horst

2006-01-01T23:59:59.000Z

417

Has the QCD Critical Point been Signaled by Observations at RHIC ?  

E-Print Network [OSTI]

The shear viscosity to entropy ratio ($\\eta/s$) is estimated for the hot and dense QCD matter created in Au+Au collisions at RHIC ($\\sqrt{s_{NN}}=200$ GeV). A very low value is found $\\eta/s \\sim 0.1$, which is close to the conjectured lower bound ($1/4\\pi$). It is argued that such a low value is indicative of thermodynamic trajectories for the decaying matter which lie close to the QCD critical end point.

Roy A. Lacey; N. N. Ajitanand; J. M. Alexander; P. Chung; W. G. Holzmann; M. Issah; A. Taranenko; P. Danielewicz; Horst Stocker

2006-09-18T23:59:59.000Z

418

Charm Quark Energy Loss In Infinite QCD Matter Using A Parton Cascade Model  

E-Print Network [OSTI]

We utilize the Parton Cascade Model to study the evolution of charm quarks propagating through a thermal brick of QCD matter. We determine the energy loss and the transport coefficient '$\\hat{q}$' for charm quarks. The calculations are done at a constant temperature of 350 MeV and the results are compared to analytical calculations of heavy quark energy loss in order to validate the applicability of using a Parton Cascade Model for the study of heavy quarks dynamics in hot and dense QCD matter.

Mohammed Younus; Christopher E. Coleman-Smith; Steffen A. Bass; Dinesh K. Srivastava

2015-01-27T23:59:59.000Z

419

QCD CORRECTIONS TO DILEPTON PRODUCTION NEAR PARTONIC THRESHOLD IN PP SCATTERING.  

SciTech Connect (OSTI)

We present a recent study of the QCD corrections to dilepton production near partonic threshold in transversely polarized {bar p}p scattering, We analyze the role of the higher-order perturbative QCD corrections in terms of the available fixed-order contributions as well as of all-order soft-gluon resummations for the kinematical regime of proposed experiments at GSI-FAIR. We find that perturbative corrections are large for both unpolarized and polarized cross sections, but that the spin asymmetries are stable. The role of the far infrared region of the momentum integral in the resummed exponent and the effect of the NNLL resummation are briefly discussed.

SHIMIZU, H.; STERMAN, G.; VOGELSANG, W.; YOKOYA, H.

2005-10-02T23:59:59.000Z

420

Electron-Ion Collider - taking us to the next QCD frontier  

E-Print Network [OSTI]

In this talk, I demonstrate that the proposed Electron-Ion Collider (EIC) will be an ideal and unique future facility to address many overarching questions about QCD and strong interaction physics at one place. The EIC will be the world's first polarized electron-proton (and light ion), as well as the first electron-nucleus collider at flexible collision energies. With its high luminosity and beam polarization, the EIC distinguishes itself from HERA and the other fixed target electron-hadron facilities around the world. The EIC is capable of taking us to the next QCD frontier to explore the glue that binds us all.

Jian-Wei Qiu

2014-12-08T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Two-flavor QCD phases and condensates at finite isospin chemical potential  

E-Print Network [OSTI]

We study the phase structure and condensates of two-flavor QCD at finite isospin chemical potential in the framework of a confining, Dyson-Schwinger equation model. We find that the pion superfluidity phase is favored at high enough isospin chemical potential. A new gauge invariant mixed quark-gluon condensate induced by isospin chemical potential is proposed based on Operator Product Expansion. We investigate the sign and magnitude of this new condensate and show that it's an important condensate in QCD sum rules at finite isospin density.

Zhao Zhang; Yu-xin Liu

2007-02-06T23:59:59.000Z

422

Some remarks on the use of effective Lagrangians in QED and QCD  

E-Print Network [OSTI]

We discuss in this article the usefulness of the effective Lagrangians (L_eff) of QED and QCD within the one-loop approximation. Instead of calculating L_eff via complicated computations with Schwinger's proper-time technique or Feynman graphs, we prefer to employ the energy-momentum tensor and the leading-log model. The advantage is that we do not have to demand the external electromagnetic or color field to be constant. There are also some critical remarks added which cast doubt on the use of LQCD with covariant constant fields in explaining the nature of the QCD vacuum.

Dittrich, Walter

2015-01-01T23:59:59.000Z

423

Some remarks on the use of effective Lagrangians in QED and QCD  

E-Print Network [OSTI]

We discuss in this article the usefulness of the effective Lagrangians (L_eff) of QED and QCD within the one-loop approximation. Instead of calculating L_eff via complicated computations with Schwinger's proper-time technique or Feynman graphs, we prefer to employ the energy-momentum tensor and the leading-log model. The advantage is that we do not have to demand the external electromagnetic or color field to be constant. There are also some critical remarks added which cast doubt on the use of LQCD with covariant constant fields in explaining the nature of the QCD vacuum.

Walter Dittrich

2015-01-29T23:59:59.000Z

424

Quantum Theory of Economics  

E-Print Network [OSTI]

In the given work the first attempt to generalize quantum uncertainty relation on macro objects is made. Business company as one of economical process participants was chosen by the authors for this purpose. The analogies between quantum micro objects and the structures which from the first sight do not have anything in common with physics are given. The proof of generalized uncertainty relation is produced. With the help of generalized uncertainty relation the authors wanted to elaborate a new non-traditional approach to the description of companies' business activity and their developing and try to formulate some advice for them. Thus, our work makes the base of quantum theory of econimics

Vladimir I. Zverev; Alexander M. Tishin

2009-01-29T23:59:59.000Z

425

Intrinsic Time Quantum Geometrodynamics  

E-Print Network [OSTI]

Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

Eyo Eyo Ita III; Chopin Soo; Hoi-Lai Yu

2015-02-06T23:59:59.000Z

426

Critically damped quantum search  

E-Print Network [OSTI]

Although measurement and unitary processes can accomplish any quantum evolution in principle, thinking in terms of dissipation and damping can be powerful. We propose a modification of Grover's algorithm in which the idea of damping plays a natural role. Remarkably, we have found that there is a critical damping value that divides between the quantum $O(\\sqrt{N})$ and classical O(N) search regimes. In addition, by allowing the damping to vary in a fashion we describe, one obtains a fixed-point quantum search algorithm in which ignorance of the number of targets increases the number of oracle queries only by a factor of 1.5.

Ari Mizel

2008-10-02T23:59:59.000Z

427

Quantum convolutional stabilizer codes  

E-Print Network [OSTI]

constructions of good quantum error-correcting codes were given by Steane [2] and Calderbank and Shor [3]. These codes protect the quantum information using additional qubits and make it possible to reverse the e®ects of the most likely errors. 10 Encouraged... is that accurate computation does not require perfect physical devices. B. Background The ¯rst quantum error correcting codes were discovered independently by Shor [1] and Steane [2], as mentioned in the previous section. Shor proved that 9 qubits could be used...

Chinthamani, Neelima

2004-09-30T23:59:59.000Z

428

Linear Quantum Feedback Networks  

E-Print Network [OSTI]

The mathematical theory of quantum feedback networks has recently been developed for general open quantum dynamical systems interacting with bosonic input fields. In this article we show, for the special case of linear dynamical systems Markovian systems with instantaneous feedback connections, that the transfer functions can be deduced and agree with the algebraic rules obtained in the nonlinear case. Using these rules, we derive the the transfer functions for linear quantum systems in series, in cascade, and in feedback arrangements mediated by beam splitter devices.

J. Gough; R. Gohm; M. Yanagisawa

2008-07-15T23:59:59.000Z

429

Intrinsic Time Quantum Geometrodynamics  

E-Print Network [OSTI]

Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental canonical commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

Eyo Eyo Ita III; Chopin Soo; Hoi-Lai Yu

2015-01-26T23:59:59.000Z

430

Light baryon spectroscopy  

SciTech Connect (OSTI)

The spectrum of excited baryons serves as an excellent probe of quantum chromodynamics (QCD). In particular, highly-excited baryon resonances are sensitive to the details of quark confinement which is only poorly understood within QCD. Facilities worldwide such as Jefferson Lab, ELSA, and MAMI, which study the systematics of hadron spectra in photo- and electroproduction experiments, have accumulated a large amount of data in recent years including unpolarized cross section and polarization data for a large variety of meson-production reactions. These are important steps toward complete experiments that will allow us to unambiguously determine the scattering amplitude in the underlying reactions and to identify the broad and overlapping baryon resonance contributions. Several new nucleon resonances have been proposed and changes to the baryon listing in the 2012 Review of Particle Physics reflect the progress in the field.

Crede, Volker [Florida State University, Department of Physics, Tallahassee, FL (United States)

2013-03-25T23:59:59.000Z

431

Energy Dependence of $K/?$, $p/?$, and $K/p$ Fluctuations in Au+Au Collisions from $\\rm \\sqrt{s_{NN}}$ = 7.7 to 200 GeV  

E-Print Network [OSTI]

A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy-ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical $K/\\pi$, $p/\\pi$, and $K/p$ fluctuations as measured by the STAR experiment in central 0-5% Au+Au collisions from center-of-mass collision energies $\\rm \\sqrt{s_{NN}}$ = 7.7 to 200 GeV are presented. The observable $\\rm \

STAR Collaboration; N. M. Abdelwahab; L. Adamczyk; J. K. Adkins; G. Agakishiev; M. M. Aggarwal; Z. Ahammed; I. Alekseev; J. Alford; C. D. Anson; A. Aparin; D. Arkhipkin; E. C. Aschenauer; G. S. Averichev; A. Banerjee; D. R. Beavis; R. Bellwied; A. Bhasin; A. K. Bhati; P. Bhattarai; J. Bielcik; J. Bielcikova; L. C. Bland; I. G. Bordyuzhin; W. Borowski; J. Bouchet; A. V. Brandin; S. G. Brovko; S. Bültmann; I. Bunzarov; T. P. Burton; J. Butterworth; H. Caines; M. Calderón de la Barca Sánchez; J. M. Campbell; D. Cebra; R. Cendejas; M. C. Cervantes; P. Chaloupka; Z. Chang; S. Chattopadhyay; H. F. Chen; J. H. Chen; L. Chen; J. Cheng; M. Cherney; A. Chikanian; W. Christie; J. Chwastowski; M. J. M. Codrington; G. Contin; J. G. Cramer; H. J. Crawford; X. Cui; S. Das; A. Davila Leyva; L. C. De Silva; R. R. Debbe; T. G. Dedovich; J. Deng; A. A. Derevschikov; R. Derradi de Souza; B. di Ruzza; L. Didenko; C. Dilks; F. Ding; P. Djawotho; X. Dong; J. L. Drachenberg; J. E. Draper; C. M. Du; L. E. Dunkelberger; J. C. Dunlop; L. G. Efimov; J. Engelage; K. S. Engle; G. Eppley; R. Esha; L. Eun; O. Evdokimov; O. Eyser; R. Fatemi; S. Fazio; J. Fedorisin; P. Filip; Y. Fisyak; C. E. Flores; C. A. Gagliardi; D. R. Gangadharan; D. Garand; F. Geurts; A. Gibson; M. Girard; S. Gliske; L. Greiner; D. Grosnick; D. S. Gunarathne; Y. Guo; A. Gupta; S. Gupta; W. Guryn; B. Haag; A. Hamad; A. Hamed; L-X. Han; R. Haque; J. W. Harris; S. Heppelmann; A. Hirsch; G. W. Hoffmann; D. J. Hofman; S. Horvat; B. Huang; H. Z. Huang; X. Huang; P. Huck; T. J. Humanic; G. Igo; W. W. Jacobs; H. Jang; E. G. Judd; S. Kabana; D. Kalinkin; K. Kang; K. Kauder; H. W. Ke; D. Keane; A. Kechechyan; A. Kesich; Z. H. Khan; D. P. Kikola; I. Kisel; A. Kisiel; D. D. Koetke; T. Kollegger; J. Konzer; I. Koralt; L. K. Kosarzewski; L. Kotchenda; A. F. Kraishan; P. Kravtsov; K. Krueger; I. Kulakov; L. Kumar; R. A. Kycia; M. A. C. Lamont; J. M. Landgraf; K. D. Landry; J. Lauret; A. Lebedev; R. Lednicky; J. H. Lee; C. Li; W. Li; X. Li; X. Li; Y. Li; Z. M. Li; M. A. Lisa; F. Liu; T. Ljubicic; W. J. Llope; M. Lomnitz; R. S. Longacre; X. Luo; G. L. Ma; Y. G. Ma; D. P. Mahapatra; R. Majka; S. Margetis; C. Markert; H. Masui; H. S. Matis; D. McDonald; T. S. McShane; N. G. Minaev; S. Mioduszewski; B. Mohanty; M. M. Mondal; D. A. Morozov; M. K. Mustafa; B. K. Nandi; Md. Nasim; T. K. Nayak; J. M. Nelson; G. Nigmatkulov; L. V. Nogach; S. Y. Noh; J. Novak; S. B. Nurushev; G. Odyniec; A. Ogawa; K. Oh; A. Ohlson; V. Okorokov; E. W. Oldag; D. L. Olvitt Jr.; B. S. Page; Y. X. Pan; Y. Pandit; Y. Panebratsev; T. Pawlak; B. Pawlik; H. Pei; C. Perkins; P. Pile; M. Planinic; J. Pluta; N. Poljak; K. Poniatowska; J. Porter; A. M. Poskanzer; N. K. Pruthi; M. Przybycien; J. Putschke; H. Qiu; A. Quintero; S. Ramachandran; R. Raniwala; S. Raniwala; R. L. Ray; C. K. Riley; H. G. Ritter; J. B. Roberts; O. V. Rogachevskiy; J. L. Romero; J. F. Ross; A. Roy; L. Ruan; J. Rusnak; O. Rusnakova; N. R. Sahoo; P. K. Sahu; I. Sakrejda; S. Salur; A. Sandacz; J. Sandweiss; E. Sangaline; A. Sarkar; J. Schambach; R. P. Scharenberg; A. M. Schmah; W. B. Schmidke; N. Schmitz; J. Seger; P. Seyboth; N. Shah; E. Shahaliev; P. V. Shanmuganathan; M. Shao; B. Sharma; W. Q. Shen; S. S. Shi; Q. Y. Shou; E. P. Sichtermann; M. Simko; M. J. Skoby; D. Smirnov; N. Smirnov; D. Solanki; P. Sorensen; H. M. Spinka; B. Srivastava; T. D. S. Stanislaus; J. R. Stevens; R. Stock; M. Strikhanov; B. Stringfellow; M. Sumbera; X. Sun; X. M. Sun; Y. Sun; Z. Sun; B. Surrow; D. N. Svirida; T. J. M. Symons; M. A. Szelezniak; J. Takahashi; A. H. Tang; Z. Tang; T. Tarnowsky; J. H. Thomas; A. R. Timmins; D. Tlusty; M. Tokarev; S. Trentalange; R. E. Tribble; P. Tribedy; B. A. Trzeciak; O. D. Tsai; J. Turnau; T. Ullrich; D. G. Underwood; G. Van Buren; G. van Nieuwenhuizen; M. Vandenbroucke; J. A. Vanfossen, Jr.; R. Varma; G. M. S. Vasconcelos; A. N. Vasiliev; R. Vertesi; F. Videbæk; Y. P. Viyogi; S. Vokal; S. A. Voloshin; A. Vossen; M. Wada; F. Wang; G. Wang; H. Wang; J. S. Wang; X. L. Wang; Y. Wang; Y. Wang; G. Webb; J. C. Webb; L. Wen; G. D. Westfall; H. Wieman; S. W. Wissink; Y. F. Wu; Z. Xiao; W. Xie; K. Xin; H. Xu; J. Xu; N. Xu; Q. H. Xu; Y. Xu; Z. Xu; W. Yan; C. Yang; Y. Yang; Y. Yang; Z. Ye; P. Yepes; L. Yi; K. Yip; I-K. Yoo; N. Yu; H. Zbroszczyk; W. Zha; J. B. Zhang; J. L. Zhang; S. Zhang; X. P. Zhang; Y. Zhang; Z. P. Zhang; F. Zhao; J. Zhao; C. Zhong; X. Zhu; Y. H. Zhu; Y. Zoulkarneeva; M. Zyzak

2014-10-21T23:59:59.000Z

432

Spin-Flavor van der Waals Forces and NN interaction  

SciTech Connect (OSTI)

A major goal in Nuclear Physics is the derivation of the Nucleon-Nucleon (NN) interaction from Quantum Chromodynamics (QCD). In QCD the fundamental degrees of freedom are colored quarks and gluons which are confined to form colorless strongly interacting hadrons. Because of this the resulting nuclear forces at sufficiently large distances correspond to spin-flavor excitations, very much like the dipole excitations generating the van der Waals (vdW) forces acting between atoms. We study the Nucleon-Nucleon interaction in the Born-Oppenheimer approximation at second order in perturbation theory including the Delta resonance as an intermediate state. The potential resembles strongly chiral potentials computed either via soliton models or chiral perturbation theory and has a van der Waals like singularity at short distances which is handled by means of renormalization techniques. Results for the deuteron are discussed.

Alvaro Calle Cordon, Enrique Ruiz Arriola

2011-12-01T23:59:59.000Z

433

Nonlinear Quantum Gravity  

E-Print Network [OSTI]

Nonlinear quantum mechanics at the Planck scale can produce nonlocal effects contributing to resolution of singularities, to cosmic acceleration, and modified black-hole dynamics, while avoiding the usual causality issues.

George Svetlichny

2006-02-01T23:59:59.000Z

434

Terahertz quantum cascade lasers  

E-Print Network [OSTI]

The development of the terahertz frequency range has long been impeded by the relative dearth of compact, coherent radiation sources of reasonable power. This thesis details the development of quantum cascade lasers (QCLs) ...

Williams, Benjamin S. (Benjamin Stanford), 1974-

2003-01-01T23:59:59.000Z

435

Experimental Satellite Quantum Communications  

E-Print Network [OSTI]

Quantum Communications on planetary scale require complementary channels including ground and satellite links. The former have progressed up to commercial stage using fiber-cables, while for satellite links, the absence of terminals in orbit has impaired theirs development. However, the demonstration of the feasibility of such links is crucial for designing space payloads and to eventually enable the realization of protocols such as quantum-key-distribution (QKD) and quantum teleportation along satellite-to-ground or intersatellite links. We demonstrated the faithful transmission of qubits from space to ground by exploiting satellite corner cube retroreflectors acting as transmitter in orbit, obtaining a low error rate suitable for QKD. We also propose a two-way QKD protocol exploiting modulated retroreflectors that necessitates a minimal payload on satellite, thus facilitating the expansion of Space Quantum Communications.

Giuseppe Vallone; Davide Bacco; Daniele Dequal; Simone Gaiarin; Vincenza Luceri; Giuseppe Bianco; Paolo Villoresi

2014-06-16T23:59:59.000Z

436

Quantum Complex Minkowski Space  

E-Print Network [OSTI]

The complex Minkowski phase space has the physical interpretation of the phase space of the scalar massive conformal particle. The aim of the paper is the construction and investigation of the quantum complex Minkowski space.

Grzegorz Jakimowicz; Anatol Odzijewicz

2005-05-06T23:59:59.000Z

437

A Quantum Production Model  

E-Print Network [OSTI]

The production system is a theoretical model of computation relevant to the artificial intelligence field allowing for problem solving procedures such as hierarchical tree search. In this work we explore some of the connections between artificial intelligence and quantum computation by presenting a model for a quantum production system. Our approach focuses on initially developing a model for a reversible production system which is a simple mapping of Bennett's reversible Turing machine. We then expand on this result in order to accommodate for the requirements of quantum computation. We present the details of how our proposition can be used alongside Grover's algorithm in order to yield a speedup comparatively to its classical counterpart. We discuss the requirements associated with such a speedup and how it compares against a similar quantum hierarchical search approach.

Luís Tarrataca; Andreas Wichert

2015-02-06T23:59:59.000Z

438

Geometrically frustrated quantum magnets  

E-Print Network [OSTI]

(cont.) more general lessons on frustrated quantum magnetism. At the end, we demonstrate some new mathematical tools on two other frustrated two-dimensional systems, and summarize our conclusions, with an outlook to remaining ...

Nikolić , Predrag, 1974-

2004-01-01T23:59:59.000Z

439

Optical Quantum Computation  

E-Print Network [OSTI]

We review the field of Optical Quantum Computation, considering the various implementations that have been proposed and the experimental progress that has been made toward realizing them. We examine both linear and nonlinear approaches and both particle and field encodings. In particular we discuss the prospects for large scale optical quantum computing in terms of the most promising physical architectures and the technical requirements for realizing them.

T. C. Ralph; G. J. Pryde

2011-03-31T23:59:59.000Z

440

Quantum error control codes  

E-Print Network [OSTI]

QUANTUM ERROR CONTROL CODES A Dissertation by SALAH ABDELHAMID AWAD ALY AHMED Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 2008 Major... Subject: Computer Science QUANTUM ERROR CONTROL CODES A Dissertation by SALAH ABDELHAMID AWAD ALY AHMED Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY...

Abdelhamid Awad Aly Ahmed, Sala

2008-10-10T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Quantum Subcritical Bubbles  

E-Print Network [OSTI]

We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in the quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using quantum statistical average. Furthermore based on our study, we give implication on the dynamics of phase transition.

Tomoko Uesugi; Masahiro Morikawa; Tetsuya Shiromizu

1996-06-26T23:59:59.000Z

442

Turbocharging Quantum Tomography.  

SciTech Connect (OSTI)

Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography su %7C ers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. We describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more e %7C ectively detect and characterize quantum noise using carefully tailored ensembles of input states.

Blume-Kohout, Robin J; Gamble, John King,; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael

2015-01-01T23:59:59.000Z

443

Nested Quantum Error Correction Codes  

E-Print Network [OSTI]

The theory of quantum error correction was established more than a decade ago as the primary tool for fighting decoherence in quantum information processing. Although great progress has already been made in this field, limited methods are available in constructing new quantum error correction codes from old codes. Here we exhibit a simple and general method to construct new quantum error correction codes by nesting certain quantum codes together. The problem of finding long quantum error correction codes is reduced to that of searching several short length quantum codes with certain properties. Our method works for all length and all distance codes, and is quite efficient to construct optimal or near optimal codes. Two main known methods in constructing new codes from old codes in quantum error-correction theory, the concatenating and pasting, can be understood in the framework of nested quantum error correction codes.

Zhuo Wang; Kai Sun; Hen Fan; Vlatko Vedral

2009-09-28T23:59:59.000Z

444

Thermodynamics in 2+1 flavor QCD with improved Wilson quarks by the fixed scale approach  

E-Print Network [OSTI]

We study thermodynamic properties of 2+1 flavor QCD with improved Wilson quarks coupled with the RG improved Iwasaki glue, using the fixed scale approach. We present the results for the equation of state, renormalized Polyakov loop, and chiral condensate.

T. Umeda; S. Aoki; S. Ejiri; T. Hatsuda; K. Kanaya; Y. Maezawa; H. Ohno

2012-12-06T23:59:59.000Z

445

Comment on chiral symmetry restoration at finite density in large-$N_c$ QCD  

E-Print Network [OSTI]

In the article "On chiral symmetry restoration at finite density in large-$N_c$ QCD" by Adhikari, Cohen, Ayyagari and Strother [Phys. Rev. C 83, 065201 (2011)] the description of dense nuclear matter by means of Skyrmions in hyperspherical unit cells is severely criticized. We point out that this criticism is based on invalid assumptions and therefore unwarranted.

Hilmar Forkel

2014-09-06T23:59:59.000Z

446

Gell-Mann - Low Function for QCD in the strong-coupling limit  

E-Print Network [OSTI]

The Gell-Mann - Low function \\beta(g) in QCD (g=g0^2/16\\pi^2 where g0 is the coupling constant in the Lagrangian) is shown to behave in the strong-coupling region as \\beta_\\infty g^\\alpha with \\alpha\\approx -13, \\beta_\\infty\\sim 10^5.

I. M. Suslov

2006-05-10T23:59:59.000Z

447

Probing the QCD Critical Point with Higher Moments of Net-proton Multiplicity Distributions  

E-Print Network [OSTI]

Higher moments of event-by-event net-proton multiplicity distributions are applied to search for the QCD critical point in the heavy ion collisions. It has been demonstrated that higher moments as well as moment products are sensitive to the correlation length and directly connected to the thermodynamic susceptibilities computed in the Lattice QCD and Hadron Resonance Gas (HRG) model. In this paper, we will present measurements for kurtosis ($\\kappa$), skewness ($S$) and variance ($\\sigma^{2}$) of net-proton multiplicity distributions at the mid-rapidity ($|y|net-proton distributions, which are related to volume independent baryon number susceptibility ratio, are compared to the Lattice QCD and HRG model calculations. The $\\kappa \\sigma^{2}$ and $S \\sigma$ of net-proton distributions are consistent with Lattice QCD and HRG model calculations at high energy, which support the thermalization of the colliding system. Deviations of $\\kappa \\sigma^{2}$ and $S \\sigma$ for the Au+Au collisions at low energies from HRG model calculations are also observed.

Xiaofeng Luo

2011-06-15T23:59:59.000Z

448

The Heavy Quark Free-Energy at TQCD  

E-Print Network [OSTI]

Starting with the modified AdS/QCD metric developed in Ref.[1] we use the Nambu-Goto action to obtain the free energy of a quark-antiquark pair at T

K. Veshgini; E. Megias; J. Nian; H. J. Pirner

2009-11-09T23:59:59.000Z

449

Modeling pion physics in the $?$-regime of two-flavor QCD using strong coupling lattice QED  

E-Print Network [OSTI]

In order to model pions of two-flavor QCD we consider a lattice field theory involving two flavors of staggered quarks interacting strongly with U(1) gauge fields. For massless quarks, this theory has an $SU_L(2)\\times SU_R(2) \\times U_A(1)$ symmetry. By adding a four-fermion term we can break the U_A(1) symmetry and thus incorporate the physics of the QCD anomaly. We can also tune the pion decay constant F, to be small compared to the lattice cutoff by starting with an extra fictitious dimension, thus allowing us to model low energy pion physics in a setting similar to lattice QCD from first principles. However, unlike lattice QCD, a major advantage of our model is that we can easily design efficient algorithms to compute a variety of quantities in the chiral limit. Here we show that the model reproduces the predictions of chiral perturbation theory in the $\\epsilon$-regime.

D. J. Cecile; Shailesh Chandrasekharan

2007-08-03T23:59:59.000Z

450

Higher twist contributions to lepton-pair production and other QCD processes  

SciTech Connect (OSTI)

A general discussion of the calculations and phenomenological consequences of power-law suppressed QCD processes is given with emphasis on tests in massive lepton pair production. Absolutely normalized predictions are given for the leading twist (transverse current) and higher twist (longitudinal current) contributions to the meson structure function in the region of large x.

Brodsky, S.J.; Berger, E.L.; Lepage, G.P.

1982-12-01T23:59:59.000Z

451

Multi-Jet Processes in the High Energy Limit of QCD.  

E-Print Network [OSTI]

This research was supported by PPARC (postdoctoral fellowship PPA/P/S/2003/00281). References 1. V. S. Fadin, R. Fiore, M. G. Kozlov, and A. V. Reznichenko, Proof of the multi-Regge form of QCD amplitudes with gluon exchanges in the NLA, hep-ph/0602006. 2. J. R...

Andersen, Jeppe R

452

Iso-vector form factors of the delta and nucleon in QCD sum rules  

SciTech Connect (OSTI)

Form factors are important non-perturbative properties of hadrons. They give information about the internal structure of the hadrons. In this work, iso-vector axial-vector and iso-vector tensor form factors of the nucleon and the iso-vector axial-vector {Delta}{yields}N transition form factor calculations in QCD Sum Rules are presented.

Ozpineci, A. [Physics Department, Middle East Technical University, 06800 (Turkey)

2012-10-23T23:59:59.000Z

453

Zero mode solutions of quark Dirac equations in QCD as the sources of chirality violating condensates  

E-Print Network [OSTI]

It is demonstrated, that chirality violating condensates in massless QCD arise from zero mode solutions of Dirac equations in arbitrary gluon fields. Basing of this idea, the model is suggested, which allows one to calculate quark condensate magnetic susceptibilities in the external constant electromagnetic field.

B. L. Ioffe

2009-06-01T23:59:59.000Z

454

Nuclear Physics from QCD : The Anticipated Impact of Exa-Scale Computing  

E-Print Network [OSTI]

I discuss highlights in the progress that is being made toward calculating processes of importance in nuclear physics from QCD using high performance computing. As exa-scale computing resources are expected to become available around 2017, I present current estimates of the computational resources required to accomplish central goals of nuclear physics.

Martin J. Savage

2010-12-04T23:59:59.000Z

455

Improving Quantum Algorithms for Quantum Chemistry  

E-Print Network [OSTI]

We present several improvements to the standard Trotter-Suzuki based algorithms used in the simulation of quantum chemistry on a quantum computer. First, we modify how Jordan-Wigner transformations are implemented to reduce their cost from linear or logarithmic in the number of orbitals to a constant. Our modification does not require additional ancilla qubits. Then, we demonstrate how many operations can be parallelized, leading to a further linear decrease in the parallel depth of the circuit, at the cost of a small constant factor increase in number of qubits required. Thirdly, we modify the term order in the Trotter-Suzuki decomposition, significantly reducing the error at given Trotter-Suzuki timestep. A final improvement modifies the Hamiltonian to reduce errors introduced by the non-zero Trotter-Suzuki timestep. All of these techniques are validated using numerical simulation and detailed gate counts are given for realistic molecules.

M. B. Hastings; D. Wecker; B. Bauer; M. Troyer

2014-03-23T23:59:59.000Z

456

Strong reactions in quantum super PDEs. III: Exotic quantum supergravity  

E-Print Network [OSTI]

Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.

Agostino Prástaro

2015-03-23T23:59:59.000Z

457

Strong reactions in quantum super PDEs. III: Exotic quantum supergravity  

E-Print Network [OSTI]

Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.

Agostino Prástaro

2015-02-01T23:59:59.000Z

458

Strong reactions in quantum super PDEs. III: Exotic quantum supergravity  

E-Print Network [OSTI]

Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.

Agostino Prástaro

2015-03-10T23:59:59.000Z

459

Quantum computation beyond the circuit model  

E-Print Network [OSTI]

The quantum circuit model is the most widely used model of quantum computation. It provides both a framework for formulating quantum algorithms and an architecture for the physical construction of quantum computers. However, ...

Jordan, Stephen Paul

2008-01-01T23:59:59.000Z

460

Echo of the Quantum Bounce  

E-Print Network [OSTI]

We identify a signature of quantum gravitational effects that survives from the early universe to the current era: Fluctuations of quantum fields as seen by comoving observers are significantly influenced by the history of the early universe. In particular we show how the existence (or not) of a quantum bounce leaves a trace in the background quantum noise that is not damped and would be non-negligible even nowadays. Furthermore, we estimate an upper bound for the typical energy and length scales where quantum effects are relevant. We discuss how this signature might be observed and therefore used to build falsifiability tests of quantum gravity theories.

Luis J. Garay; Mercedes Martin-Benito; Eduardo Martin-Martinez

2014-02-15T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

On description of quantum plasma  

E-Print Network [OSTI]

A plasma becomes quantum when the quantum nature of its particles significantly affects its macroscopic properties. To answer the question of when the collective quantum plasma effects are important, a proper description of such effects is necessary. We consider here the most common methods of description of quantum plasma, along with the related assumptions and applicability limits. In particular, we analyze in detail the hydrodynamic description of quantum plasma, as well as discuss some kinetic features of analytic properties of linear dielectric response function in quantum plasma. We point out the most important, in our view, fundamental problems occurring already in the linear approximation and requiring further investigation. (submitted to Physics-Uspekhi)

S. V. Vladimirov; Yu. O. Tyshetskiy

2011-01-21T23:59:59.000Z

462

Setting the Renormalization Scale in QCD: The Principle of Maximum Conformality  

SciTech Connect (OSTI)

A key problem in making precise perturbative QCD predictions is the uncertainty in determining the renormalization scale {mu} of the running coupling {alpha}{sub s}({mu}{sup 2}): The purpose of the running coupling in any gauge theory is to sum all terms involving the {beta} function; in fact, when the renormalization scale is set properly, all non-conformal {beta} {ne} 0 terms in a perturbative expansion arising from renormalization are summed into the running coupling. The remaining terms in the perturbative series are then identical to that of a conformal theory; i.e., the corresponding theory with {beta} = 0. The resulting scale-fixed predictions using the 'principle of maximum conformality' (PMC) are independent of the choice of renormalization scheme - a key requirement of renormalization group invariance. The results avoid renormalon resummation and agree with QED scale-setting in the Abelian limit. The PMC is also the theoretical principle underlying the BLM procedure, commensurate scale relations between observables, and the scale-setting method used in lattice gauge theory. The number of active flavors nf in the QCD {beta} function is also correctly determined. We discuss several methods for determining the PMC/BLM scale for QCD processes. We show that a single global PMC scale, valid at leading order, can be derived from basic properties of the perturbative QCD cross section. The elimination of the renormalization scheme ambiguity using the PMC will not only increase the precision of QCD tests, but it will also increase the sensitivity of collider experiments to new physics beyond the Standard Model.

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Di Giustino, Leonardo; /SLAC

2011-08-19T23:59:59.000Z

463

A bird's eye view of quantum computers  

E-Print Network [OSTI]

Quantum computers are discussed in the general framework of computation, the laws of physics and the foundations of quantum mechanics.

Giuliano Benenti; Giuliano Strini

2007-03-13T23:59:59.000Z

464

An algorithm for minimization of quantum cost  

E-Print Network [OSTI]

A new algorithm for minimization of quantum cost of quantum circuits has been designed. The quantum cost of different quantum circuits of particular interest (eg. circuits for EPR, quantum teleportation, shor code and different quantum arithmetic operations) are computed by using the proposed algorithm. The quantum costs obtained using the proposed algorithm is compared with the existing results and it is found that the algorithm has produced minimum quantum cost in all cases.

Anindita Banerjee; Anirban Pathak

2010-04-09T23:59:59.000Z

465

Exploiting locality in quantum computation for quantum chemistry  

E-Print Network [OSTI]

Accurate prediction of chemical and material properties from first principles quantum chemistry is a challenging task on traditional computers. Recent developments in quantum computation offer a route towards highly accurate solutions with polynomial cost, however this solution still carries a large overhead. In this perspective, we aim to bring together known results about the locality of physical interactions from quantum chemistry with ideas from quantum computation. We show that the utilization of spatial locality combined with the Bravyi-Kitaev transformation offers an improvement in the scaling of known quantum algorithms for quantum chemistry and provide numerical examples to help illustrate this point. We combine these developments to improve the outlook for the future of quantum chemistry on quantum computers.

Jarrod R. McClean; Ryan Babbush; Peter J. Love; Alán Aspuru-Guzik

2014-07-29T23:59:59.000Z

466

Quantum theory of gravitational collapse (lecture notes on quantum conchology)  

E-Print Network [OSTI]

Preliminary version No.~2 of the lecture notes for the talk ``Quantum theory of gravitational collapse'' given at the 271. WE-Heraeus-Seminar ``Aspects of Quantum Gravity'' at Bad Honnef, 25 February--1 March 2002

Petr Hajicek

2002-04-15T23:59:59.000Z

467

A Note on Quantum Security for Post-Quantum Cryptography  

E-Print Network [OSTI]

Shor's quantum factoring algorithm and a few other efficient quantum algorithms break many classical crypto-systems. In response, people proposed post-quantum cryptography based on computational problems that are believed hard even for quantum computers. However, security of these schemes against \\emph{quantum} attacks is elusive. This is because existing security analysis (almost) only deals with classical attackers and arguing security in the presence of quantum adversaries is challenging due to unique quantum features such as no-cloning. This work proposes a general framework to study which classical security proofs can be restored in the quantum setting. Basically, we split a security proof into (a sequence of) classical security reductions, and investigate what security reductions are "quantum-friendly". We characterize sufficient conditions such that a classical reduction can be "lifted" to the quantum setting. We then apply our lifting theorems to post-quantum signature schemes. We are able to show that the classical generic construction of hash-tree based signatures from one-way functions and and a more efficient variant proposed in~\\cite{BDH11} carry over to the quantum setting. Namely, assuming existence of (classical) one-way functions that are resistant to efficient quantum inversion algorithms, there exists a quantum-secure signature scheme. We note that the scheme in~\\cite{BDH11} is a promising (post-quantum) candidate to be implemented in practice and our result further justifies it. Finally we demonstrate the generality of our framework by showing that several existing works (Full-Domain hash in the quantum random-oracle model~\\cite{Zha12ibe} and the simple hybrid arguments framework in~\\cite{HSS11}) can be reformulated under our unified framework.

Fang Song

2014-09-08T23:59:59.000Z

468

Quantum Terahertz Electrodynamics and Macroscopic Quantum Tunneling in Layered Superconductors  

E-Print Network [OSTI]

of macroscopic quantum tunneling (MQT) in stacks of intrinsic Josephson junctions. Because of the long numbers: 74.72.Hs, 74.78.Fk The recent surge of interest in stacks of intrinsic Josephson junctions of stacks of Josephson junctions in quantum electronics [6]. This requires a quantum theory capable

Nori, Franco

469

Damped quantum harmonic oscillator  

E-Print Network [OSTI]

In the framework of the Lindblad theory for open quantum systems the damping of the harmonic oscillator is studied. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schr\\"odinger and Heisenberg representations of the Lindblad equation are given explicitly. On the basis of these representations it is shown that various master equations for the damped quantum oscillator used in the literature are particular cases of the Lindblad equation and that the majority of these equations are not satisfying the constraints on quantum mechanical diffusion coefficients. Analytical expressions for the first two moments of coordinate and momentum are also obtained by using the characteristic function of the Lindblad master equation. The master equation is transformed into Fokker-Planck equations for quasiprobability distributions. A comparative study is made for the Glauber $P$ representation, the antinormal ordering $Q$ representation and the Wigner $W$ representation. It is proven that the variances for the damped harmonic oscillator found with these representations are the same. By solving the Fokker-Planck equations in the steady state, it is shown that the quasiprobability distributions are two-dimensional Gaussians with widths determined by the diffusion coefficients. The density matrix is represented via a generating function, which is obtained by solving a time-dependent linear partial differential equation derived from the master equation. Illustrative examples for specific initial conditions of the density matrix are provided.

A. Isar; A. Sandulescu

2006-02-17T23:59:59.000Z

470

Heat Machines and Quantum Systems  

E-Print Network [OSTI]

Heat Machines and Quantum Systems: Towards the Third Law Thesis submitted for the degree of "Doctor Machines and Quantum Systems: Towards the Third Law Thesis submitted for the degree of "Doctor

Kosloff, Ronnie

471

A quantum dot heterojunction photodetector  

E-Print Network [OSTI]

This thesis presents a new device architecture for photodetectors utilizing colloidally grown quantum dots as the principle photo-active component. We implement a thin film of cadmium selenide (CdSe) quantum dot sensitizers, ...

Arango, Alexi Cosmos, 1975-

2005-01-01T23:59:59.000Z

472

Generalized Concatenation for Quantum Codes  

E-Print Network [OSTI]

We show how good quantum error-correcting codes can be constructed using generalized concatenation. The inner codes are quantum codes, the outer codes can be linear or nonlinear classical codes. Many new good codes are ...

Grassl, Markus

473

Faster than Light Quantum Communication  

E-Print Network [OSTI]

Faster than light communication might be possible using the collapse of the quantum wave-function without any accompanying paradoxes.

A. Y. Shiekh

2008-04-05T23:59:59.000Z

474

STOPPING TIMES IN QUANTUM MECHANICS  

E-Print Network [OSTI]

(Stinespring, Kraus). 3". Time-dependant case General time evolution of an open quantum sys- tem = (Pt)t0

Attal, Stéphane

475

Fractal properties of quantum spacetime  

E-Print Network [OSTI]

We show that in general a spacetime having a quantum group symmetry has also a scale dependent fractal dimension which deviates from its classical value at short scales, a phenomenon that resembles what observed in some approaches to quantum gravity. In particular we analyze the cases of a quantum sphere and of $\\k$-Minkowski, the latter being relevant in the context of quantum gravity.

Dario Benedetti

2009-03-25T23:59:59.000Z

476

Quantum Money with Classical Verification  

E-Print Network [OSTI]

We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it.

Dmitry Gavinsky

2012-03-15T23:59:59.000Z

477

Quantum computational webs  

E-Print Network [OSTI]

We introduce the notion of quantum computational webs: These are quantum states universal for measurement-based computation which can be built up from a collection of simple primitives. The primitive elements - reminiscent of building blocks in a construction kit - are (i) states on a one-dimensional chain of systems ("computational quantum wires") with the power to process one logical qubit and (ii) suitable couplings which connect the wires to a computationally universal "web". All elements are preparable by nearest-neighbor interactions in a single pass - a type of operation well-suited for a number of physical architectures. We provide a complete classification of qubit wires. This is first instance where a physically well-motivated class of universal resources can be fully understood. Finally, we sketch possible realizations in superlattices, and explore the power of coupling mechanisms based on Ising or exchange-interactions.

D. Gross; J. Eisert

2010-05-01T23:59:59.000Z

478

Optical Quantum Computing  

E-Print Network [OSTI]

In 2001 all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single photon sources, linear optical elements, and single photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high efficiency single photon detectors, and low-loss interfacing of these components.

Jeremy L. O'Brien

2008-03-11T23:59:59.000Z

479

Efficient Quantum Ratchet  

E-Print Network [OSTI]

Quantum resonance is one of the main characteristics of the quantum kicked rotor, which has been used to induce accelerated ratchet current of the particles with a generalized asymmetry potential. Here we show that by desynchronizing the kicked potentials of the flashing ratchet [Phys. Rev. Lett. 94, 110603 (2005)], new quantum resonances are stimulated to conduct directed currents more efficiently. Most distinctly, the missed resonances $\\kappa=1.0\\pi$ and $\\kappa=3.0\\pi$ are created out to induce even larger currents. At the same time, with the help of semiclassical analysis, we prove that our result is exact rather than phenomenon induced by errors of the numerical simulation. Our discovery may be used to realize directed transport efficiently, and may also lead to a deeper understanding of symmetry breaking for the dynamical evolution.

Chuan-Feng Li; Rong-Chun Ge; Guang-Can Guo

2012-06-16T23:59:59.000Z

480

Quantum cosmology: a review  

E-Print Network [OSTI]

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.

Bojowald, Martin

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum chromodynamics qcd" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Quantum cosmology: a review  

E-Print Network [OSTI]

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.

Martin Bojowald

2015-01-20T23:59:59.000Z

482

QKD Quantum Channel Authentication  

E-Print Network [OSTI]

Several simple yet secure protocols to authenticate the quantum channel of various QKD schemes, by coupling the photon sender's knowledge of a shared secret and the QBER Bob observes, are presented. It is shown that Alice can encrypt certain portions of the information needed for the QKD protocols, using a sequence whose security is based on computational-complexity, without compromising all of the sequence's entropy. It is then shown that after a Man-in-the-Middle attack on the quantum and classical channels, there is still enough entropy left in the sequence for Bob to detect the presence of Eve by monitoring the QBER. Finally, it is shown that the principles presented can be implemented to authenticate the quantum channel associated with any type of QKD scheme, and they can also be used for Alice to authenticate Bob.

J. T. Kosloski

2006-04-02T23:59:59.000Z

483

The Quantum Mellin transform  

E-Print Network [OSTI]

We uncover a new type of unitary operation for quantum mechanics on the half-line which yields a transformation to ``Hyperbolic phase space''. We show that this new unitary change of basis from the position x on the half line to the Hyperbolic momentum $p_\\eta$, transforms the wavefunction via a Mellin transform on to the critial line $s=1/2-ip_\\eta$. We utilise this new transform to find quantum wavefunctions whose Hyperbolic momentum representation approximate a class of higher transcendental functions, and in particular, approximate the Riemann Zeta function. We finally give possible physical realisations to perform an indirect measurement of the Hyperbolic momentum of a quantum system on the half-line.

J. Twamley; G. J. Milburn

2007-02-12T23:59:59.000Z

484

Extremal generalized quantum measurements  

E-Print Network [OSTI]

A measurement on a section K of the set of states of a finite dimensional C*-algebra is defined as an affine map from K to a probability simplex. Special cases of such sections are used in description of quantum networks, in particular quantum channels. Measurements on a section correspond to equivalence classes of so-called generalized POVMs, which are called quantum testers in the case of networks. We find extremality conditions for measurements on K and characterize generalized POVMs such that the corresponding measurement is extremal. These results are applied to the set of channels. We find explicit extremality conditions for two outcome measurements on qubit channels and give an example of an extremal qubit 1-tester such that the corresponding measurement is not extremal.

Anna Jencova

2012-07-23T23:59:59.000Z

485

Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

MILC asqtad QCD SU(3) gauge ensemble; series=a; a=0.11fm minus 0.0022fm ; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)

Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara

486

Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050b  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

MILC asqtad QCD SU(3) gauge ensemble; series=b; a=0.11fm minus 0.0022fm; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)

Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara

487

Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050b  

SciTech Connect (OSTI)

MILC asqtad QCD SU(3) gauge ensemble; series=b; a=0.11fm minus 0.0022fm; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)

Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara

2015-01-01T23:59:59.000Z

488

From Quantum Mechanics to Thermodynamics?  

E-Print Network [OSTI]

From Quantum Mechanics to Thermodynamics? Dresden, 22.11.2004 Jochen Gemmer Universit¨at Osnabr to thermodynamical behavior · Quantum approach to thermodynamical behavior · The route to equilibrium · Summary of thermodynamical behavior entirely on the basis of Hamilton models and Schr¨odinger-type quantum dynamics. · define

Steinhoff, Heinz-Jürgen

489

Time machines and quantum theory  

E-Print Network [OSTI]

There is a deep structural link between acausal spacetimes and quantum theory. As a consequence quantum theory may resolve some "paradoxes" of time travel. Conversely, non-time-orientable spacetimes naturally give rise to electric charges and spin half. If an explanation of quantum theory is possible, then general relativity with time travel could be it.

Mark J Hadley

2006-12-02T23:59:59.000Z

490

Quantum simulation I. M. Georgescu  

E-Print Network [OSTI]

, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar, Saitama, 351-0198, Japan and Qatar Environment and Energy Research Institute, Doha, Qatar Franco Nori CEMS, high-energy physics, atomic physics, quantum chemistry, and cosmology. Quantum simulation could

Nori, Franco

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Loop quantum gravity and observations  

E-Print Network [OSTI]

Quantum gravity has long been thought to be completely decoupled from experiments or observations. Although it is true that smoking guns are still missing, there are now serious hopes that quantum gravity phenomena might be tested. We review here some possible ways to observe loop quantum gravity effects either in the framework of cosmology or in astroparticle physics.

A. Barrau; J. Grain