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1

Quantum Chromodynamics  

Science Journals Connector (OSTI)

The theory of the strong interaction of elementary particles, Quantum Chromodynamics (QCD), is a non-abelian gauge theory with SU(3) as gauge group. The degrees of freedom corresponding to this SU(3) are called c...

Prof. Dr. rer. nat. Manfred Böhm…

2001-01-01T23:59:59.000Z

2

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

3

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

4

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

5

Automated Code Generation for Lattice Quantum Chromodynamics and beyond  

E-Print Network [OSTI]

We present here our ongoing work on a Domain Specific Language which aims to simplify Monte-Carlo simulations and measurements in the domain of Lattice Quantum Chromodynamics. The tool-chain, called Qiral, is used to produce high-performance OpenMP C code from LaTeX sources. We discuss conceptual issues and details of implementation and optimization. The comparison of the performance of the generated code to the well-established simulation software is also made.

Denis Barthou; Olivier Brand-Foissac; Romain Dolbeau; Gilbert Grosdidier; Christina Eisenbeis; Michael Kruse; Olivier Pene; Konstantin Petrov; Claude Tadonki

2014-01-09T23:59:59.000Z

6

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

Office of Science (SC) Website

QCDOC -Quantum Chromodynamics on a Chip QCDOC -Quantum Chromodynamics on a Chip at BNL Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Spinoff Applications Spinoff Archives SBIR/STTR Applications of Nuclear Science and Technology Funding Opportunities Nuclear Science Advisory Committee (NSAC) News & Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3613 F: (301) 903-3833 E: sc.np@science.doe.gov More Information » Spinoff Archives QCDOC -Quantum Chromodynamics on a Chip at BNL Print Text Size: A A A RSS Feeds FeedbackShare Page Application/instrumentation: Advanced high capacity computing for quantum chromodynamics Developed at: Brookhaven National Laboratory, Columbia, IBM, RIKEN

7

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

Office of Scientific and Technical Information (OSTI)

Murray Gell-Mann, the Eightfold Way, and Quantum Chromodynamics Murray Gell-Mann, the Eightfold Way, and Quantum Chromodynamics Resources with Additional Information Murray Gell-Mann Courtesy of the Santa Fe Institute 'In 1969, Professor Gell-Mann received the Nobel Prize in physics for his work on the theory of elementary particles. Professor Gell-Mann's "eightfold way" theory brought order to the chaos created by the discovery of some 100 particles in the atom's nucleus. Then he found that all of those particles, including the neutron and proton, are composed of fundamental building blocks that he named "quarks." The quarks are permanently confined by forces coming from the exchange of "gluons." He and others later constructed the quantum field theory of quarks and gluons, called "quantum chromodynamics," which seems to account for all the nuclear particles and their strong interactions." ...

8

Condensates in quantum chromodynamics and the cosmological constant  

Science Journals Connector (OSTI)

...where mesons are treated as elementary fields and QCD in which...substance, namely, (i) zero-resistance flow of electric current, and...proton subjected to a constant electric field will accelerate and...

Stanley J. Brodsky; Robert Shrock

2011-01-01T23:59:59.000Z

9

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

10

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

11

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

12

QCD in e+e? Annihilation: Theory and Practice  

Science Journals Connector (OSTI)

The promise of e+e? annihilation as an ideal laboratory to test Quantum Chromodynamics, QCD, has been the dominating theme in elementary particle physics during the last several years. In this paper an attempt is...

A. Ali

1983-01-01T23:59:59.000Z

13

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

14

Color transparency and the structure of the proton in quantum chromodynamics  

SciTech Connect (OSTI)

Many anomalies suggest that the proton itself is 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-nontrivial 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-trivial 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. As we shall see in this lecture, the apparent discrepancies with experiment are not so much a failure of QCD, but rather symptoms of the complexity and richness of the theory. An important tool for analyzing this complexity is the light-cone Fock state representation of hadron wavefunctions, which provides a consistent but convenient framework for encoding the features of relativistic many-body systems in quantum field theory. 121 refs., 44 figs., 1 tab.

Brodsky, S.J.

1989-06-01T23:59:59.000Z

15

"Quantum Field Theory and QCD"  

SciTech Connect (OSTI)

This grant partially funded a meeting, "QFT & QCD: Past, Present and Future" held at Harvard University, Cambridge, MA on March 18-19, 2005. The participants ranged from senior scientists (including at least 9 Nobel Prize winners, and 1 Fields medalist) to graduate students and undergraduates. There were several hundred persons in attendance at each lecture. The lectures ranged from superlative reviews of past progress, lists of important, unsolved questions, to provocative hypotheses for future discovery. The project generated a great deal of interest on the internet, raising awareness and interest in the open questions of theoretical physics.

Jaffe, Arthur M.

2006-02-25T23:59:59.000Z

16

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

17

The BlueGene/L Supercomputer and Quantum ChromoDynamics  

SciTech Connect (OSTI)

In summary our update contains: (1) Perfect speedup sustaining 19.3% of peak for the Wilson D D-slash Dirac operator. (2) Measurements of the full Conjugate Gradient (CG) inverter that inverts the Dirac operator. The CG inverter contains two global sums over the entire machine. Nevertheless, our measurements retain perfect speedup scaling demonstrating the robustness of our methods. (3) We ran on the largest BG/L system, the LLNL 64 rack BG/L supercomputer, and obtained a sustained speed of 59.1 TFlops. Furthermore, the speedup scaling of the Dirac operator and of the CG inverter are perfect all the way up to the full size of the machine, 131,072 cores (please see Figure II). The local lattice is rather small (4 x 4 x 4 x 16) while the total lattice has been a lattice QCD vision for thermodynamic studies (a total of 128 x 128 x 256 x 32 lattice sites). This speed is about five times larger compared to the speed we quoted in our submission. As we have pointed out in our paper QCD is notoriously sensitive to network and memory latencies, has a relatively high communication to computation ratio which can not be overlapped in BGL in virtual node mode, and as an application is in a class of its own. The above results are thrilling to us and a 30 year long dream for lattice QCD.

Vranas, P; Soltz, R

2006-10-19T23:59:59.000Z

18

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

19

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

20

Nuclear Physics from Lattice QCD  

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

Physics from Lattice QCD Physics from Lattice QCD Resources at NERSC Martin J. Savage, Robert Edwards and Chip Watson May 2011, Washington D.C. Science : 20 mins : Martin Savage Hardware : 15 mins : Chip Watson Code, Algorithms, Production : 35 mins : Robert Edwards (Massimo DiPierro) Topological Charge Density Thursday, May 26, 2011 Spin-pairing Shell-structure Vibrational and rotational excitations Λ QCD m u Λ QCD m d Λ QCD m s Λ QCD α e Small number of input parameters responsible for all of strongly interacting matter Quarks and Gluons Proton Nucleus The Structure and Interactions of Matter from Quantum Chromodynamics Thursday, May 26, 2011 Exa-Scale Computational Resources Nuclear Astrophysics Accelerator Physics

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

High Energy Physics Division, ANL Lattice QCD  

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

Energy Energy Physics Division, ANL Lattice QCD in extreme environments D. K. Sinclair (HEP, Argonne) J. B. Kogut (Physics, Illinois) D. Toublan (Physics, Illinois) 1 Lattice QCD Quantum chromodynamics(QCD) de- scribes Hadrons and their strong inter- actions. Hadrons consist of quarks held together by gluons. Lattice QCD is QCD on a 4-dimensional (space-time) lattice. Allows numerical simulation of the functional integrals which define this quantum field theory, and non-perturbative QCD calculations. Physics - properties of hadrons (masses, etc.), hadronic matrix elements (HEP), hadronic matter at finite temperature and/or densities (RHIC, early universe, neutron stars). 2 Computational Methods * Functional integral is mapped to the partition function for a classical sys- tem. Molecular-dynamics methods are used to calculate the observables for this classical system.

22

Confined Monopoles Induced by Quantum Effects in Dense QCD  

E-Print Network [OSTI]

We analytically show that mesonic bound states of confined monopoles appear inside a non-Abelian vortex-string in massless three-flavor QCD at large quark chemical potential mu. The orientational modes CP^2 in the internal space of a vortex is described by the low-energy effective world-sheet theory. Mesons of confined monopoles are dynamically generated as bound states of kinks by the quantum effects in the effective theory. The mass of monopoles is shown to be an exponentially soft scale Delta*exp[-c*(mu/Delta)^2], with the color superconducting gap Delta and some constant c. A possible quark-monopole duality between the hadron phase and the color superconducting phase is also discussed.

Minoru Eto; Muneto Nitta; Naoki Yamamoto

2011-01-13T23:59:59.000Z

23

Confined monopoles induced by quantum effects in dense QCD  

SciTech Connect (OSTI)

We analytically show that mesonic bound states of confined monopoles appear inside a non-Abelian vortex string in massless three-flavor QCD at large quark chemical potential {mu}. The orientational modes CP{sup 2} in the internal space of a vortex is described by the low-energy effective world-sheet theory. Mesons of confined monopoles are dynamically generated as bound states of kinks by the quantum effects in the effective theory. The mass of monopoles is shown to be an exponentially soft scale M{approx}{Delta}exp[-c({mu}/{Delta}){sup 2}], with the color superconducting gap {Delta} and some constant c. A possible quark-monopole duality between the hadron phase and the color superconducting phase is also discussed.

Eto, Minoru [Mathematical Physics Laboratory, RIKEN Nishina Center, Saitama 351-0198 (Japan); Nitta, Muneto [Department of Physics, and Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan); Yamamoto, Naoki [Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550 (United States)

2011-04-15T23:59:59.000Z

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

BNL | QCD Matter, Big Bang Physics  

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

QCD Matter QCD Matter image Physicist Paul Sorensen next to the STAR detector at Brookhaven's Relativistic Heavy Ion Collider Exploring Matter at the Dawn of Time Brookhaven Lab leads the world in exploring how the matter that makes up atomic nuclei behaved just after the Big Bang. At that time, more than 13 billion years ago, there were no protons and neutrons-just a sea of "free" quarks and gluons, fundamental particles whose interactions are governed by nature's strongest force and described by the theory of quantum chromodynamics (QCD). More than 1,000 scientists from around the nation and the world come to Brookhaven to recreate this "quark-gluon plasma" by accelerating heavy ions (atoms stripped of their electrons) to nearly the speed of light and smashing them together at the Lab's

28

Paramagnetic squeezing of QCD matter  

E-Print Network [OSTI]

We determine the magnetization of Quantum Chromodynamics (QCD) for several temperatures around and above the transition between the hadronic and the quark-gluon phases of strongly interacting matter. We obtain a paramagnetic response that increases in strength with the temperature. We argue that due to this paramagnetism, chunks of quark-gluon plasma produced in non-central heavy ion collisions should become elongated along the direction of the magnetic field. This anisotropy will then contribute to the elliptic flow v_2 observed in such collisions, in addition to the pressure gradient that is usually taken into account. We present a simple estimate for the magnitude of this new effect and a rough comparison to the effect due to the initial collision geometry. We conclude that the paramagnetic effect might have a significant impact on the value of v_2.

Bali, G S; Endrodi, G; Schafer, A

2014-01-01T23:59:59.000Z

29

qcd.dvi  

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

Revised Revised October 2013 by S. Bethke (Max-Planck-Institute of Physics, Munich), G. Dissertori (ETH, Zurich) and G.P. Salam (CERN). 1.1. Basics Quantum Chromodynamics (QCD), the gauge field theory that describes the strong interactions of colored quarks and gluons, is the SU(3) component of the SU(3)×SU(2)×U(1) Standard Model of Particle Physics. The Lagrangian of QCD is given by L = q ¯ ψ q,a iγ µ ∂ µ δ ab - g s γ µ t C ab A C µ - m q δ ab ψ q,b - 1 4 F A µν F A µν , (1.1) where repeated indices are summed over. The γ µ are the Dirac γ-matrices. The ψ q,a are quark-field spinors for a quark of flavor q and mass m q , with a color-index a that runs from a = 1 to N c = 3, i.e. quarks come in three "colors." Quarks are said to be in the fundamental representation of the SU(3) color group. The A C µ correspond to the gluon fields, with C running from 1 to N 2 c - 1 = 8, i.e. there are eight kinds of

30

qcd.dvi  

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

Written Written October 2009 by G. Dissertori (ETH, Zurich) and G.P. Salam (LPTHE, Paris). 1.1. Basics Quantum Chromodynamics (QCD), the gauge field theory that describes the strong interactions of colored quarks and gluons, is the SU(3) component of the SU(3)×SU(2)×U(1) Standard Model of Particle Physics. The Lagrangian of QCD is given by L = q ¯ ψ q,a iγ µ ∂ µ δ ab - g s γ µ t C ab A C µ - m q δ ab ψ q,b - 1 4 F A µν F A µν , (1.1) where repeated indices are summed over. The γ µ are the Dirac γ-matrices. The ψ q,a are quark-field spinors for a quark of flavor q and mass m q , with a color-index a that runs from a = 1 to N c = 3, i.e. quarks come in three "colors." Quarks are said to be in the fundamental representation of the SU(3) color group. The A C µ correspond to the gluon fields, with C running from 1 to N 2 c - 1 = 8, i.e. there are eight kinds of gluon. Gluons are said to be in the adjoint representation

31

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)

32

Twenty-first Century Lattice Gauge Theory: Results from the QCD Lagrangian  

SciTech Connect (OSTI)

Quantum chromodynamics (QCD) reduces the strong interactions, in all their variety, to an elegant nonabelian gauge theory. It clearly and elegantly explains hadrons at short distances, which has led to its universal acceptance. Since its advent, however, many of its long-distance, emergent properties have been believed to be true, without having been demonstrated to be true. This paper reviews a variety of results in this regime that have been established with lattice gauge theory, directly from the QCD Lagrangian. This body of work sheds light on the origin of hadron masses, its interplay with dynamical symmetry breaking, as well as on other intriguing features such as the phase structure of QCD. In addition, nonperturbative QCD is quantitatively important to many aspects of particle physics (especially the quark flavor sector), nuclear physics, and astrophysics. This review also surveys some of the most interesting connections to those subjects.

Kronfeld, Andreas S.; /Fermilab

2012-03-01T23:59:59.000Z

33

Tests of QCD at LEP  

Science Journals Connector (OSTI)

The four experiments, ALEPH, DELPHI, L3 and OPAL at LEP, have performed a large number of precise measurements to test Quantum Chromodynamics. The strong coupling constant has been measured with high precision:? ...

Sunanda Banerjee

1993-07-01T23:59:59.000Z

34

Handbook of perturbative QCD  

Science Journals Connector (OSTI)

The elements, theoretical basis, and experimental status of perturbative quantum chromodynamics are presented. Relevant field-theoretic methods are introduced at a nonspecialist level, along with a review of the basic ideas and methods of the parton model. This is followed by an account of the fundamental theorems of quantum chromodynamics, which generalize the parton model. Summaries of the theoretical and experimental status of the most important hard-scattering processes are then given, including electron-positron annihilation, deeply inelastic scattering, and hard hadron-hadron scattering, as induced both by electoweak interactions and by quantum chromodynamics directly. In addition, a discussion is presented of the global fitting approach to the determination of parton distributions in nucleons.

George Sterman; John Smith; John C. Collins; James Whitmore; Raymond Brock; Joey Huston; Jon Pumplin; Wu-Ki Tung; Hendrik Weerts; Chien-Peng Yuan; Stephen Kuhlmann; Sanjib Mishra; Jorge G. Morfín; Fredrick Olness; Joseph Owens; Jianwei Qiu; Davison E. Soper

1995-01-01T23:59:59.000Z

35

Large Scale Computing and Storage Requirements for High Energy Physics  

E-Print Network [OSTI]

research program in Quantum Chromodynamics (QCD). This research addresses fundamental questions in high energy and nuclear

Gerber, Richard A.

2011-01-01T23:59:59.000Z

36

UKQCD software for lattice quantum chromodynamics  

Science Journals Connector (OSTI)

...global e-Infrastructure I. Selected...seen in high-energy physics experiments...space-time grid (the lattice...the rational hybrid Monte Carlo...global e-Infrastructure I. Selected...J. High Energy Phys. 7...2006The rational hybrid Monte Carlo...the rational hybrid Monte Carlo...

2009-01-01T23:59:59.000Z

37

Physics of the 1 Teraflop RIKEN-BNL-Columbia QCD project. Proceedings of RIKEN BNL Research Center workshop: Volume 13  

SciTech Connect (OSTI)

A workshop was held at the RIKEN-BNL Research Center on October 16, 1998, as part of the first anniversary celebration for the center. This meeting brought together the physicists from RIKEN-BNL, BNL and Columbia who are using the QCDSP (Quantum Chromodynamics on Digital Signal Processors) computer at the RIKEN-BNL Research Center for studies of QCD. Many of the talks in the workshop were devoted to domain wall fermions, a discretization of the continuum description of fermions which preserves the global symmetries of the continuum, even at finite lattice spacing. This formulation has been the subject of analytic investigation for some time and has reached the stage where large-scale simulations in QCD seem very promising. With the computational power available from the QCDSP computers, scientists are looking forward to an exciting time for numerical simulations of QCD.

NONE

1998-10-16T23:59:59.000Z

38

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

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

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

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.


41

From surface roughening to QCD string theory  

SciTech Connect (OSTI)

Surface critical phenomena and the related onset of Goldstone modes represent fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement and string formation are presented. Problems with a simple string description of the large Wilson surface are discussed.

Keisuke Jimmy Juge et al.

2001-05-23T23:59:59.000Z

42

Soliton states in the quantum-chromodynamic effective Lagrangian  

Science Journals Connector (OSTI)

The work of Skyrme has shown that the SU(2)×SU(2) chiral model has nontrivial topological sectors which admit solitons for generic chiral Lagrangians. In this paper, we study such models in the presence of baryon fields. The baryon number and strangeness of the solitons, and the bound states of the nucleon to the soliton are investigated. It is found that long-lived levels with large baryon number B and strangeness (?6 in magnitude) and masses somewhere in the range 1.8 to 5.6 GeV must exist. Some of these levels have half-integral electric charge and exotic relation between B and spin s (e.g., even B and half-integer s). It is speculated that these levels may be related to the anomalous nuclei whose existence has been confirmed in cosmic-ray and LBL Bevalac experiments.

A. P. Balachandran; V. P. Nair; S. G. Rajeev; A. Stern

1983-03-01T23:59:59.000Z

43

Condensates in quantum chromodynamics and the cosmological constant  

Science Journals Connector (OSTI)

...phase transitions such as liquid gas or ferromagnetic; again...localized within the hadron. There is a natural relation with the nucleon sigma term, , where...Superconductivity Super Collider Workshop, Corpus Christi, In Conclusion: A Collection of...

Stanley J. Brodsky; Robert Shrock

2011-01-01T23:59:59.000Z

44

The Conformal Template and New Perspectives for Quantum Chromodynamics  

Science Journals Connector (OSTI)

......Brodsky Stanford Linear Accelerator Center, Stanford University...tests of hidden color in nuclear wave functions, the...and antishadowing of nuclear structure functions...tests of hidden color in nuclear wave functions, the...maximal wave length, all vacuum polarization corrections......

Stanley J. Brodsky

2007-02-01T23:59:59.000Z

45

On the Determination of Elastic and Inelastic Nuclear Observables 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 the strong interaction, Quantum Chromodynamics (QCD). Currently, lattice QCD (LQCD) provides the only reliable option for performing calculations of low-energy hadronic observables. LQCD calculations are necessarily performed in a finite Euclidean spacetime. As a result, it is necessary to construct formalism that maps the finite-volume observables determined via LQCD to the infinite-volume quantities of interest. This methodology is commonly referred to as the Luscher method, as it was Martin Luscher who first developed such formalism for scalar bosons with zero total momentum below inelastic thresholds. In this work, we review recent progress on the generalization of this formalism. We present a detailed derivation of the extension of Luscher's seminal work for multi-channel two-body scalar systems, two-nucleon non-relativistic systems, and three-body non-relativistic scalar systems. For all of these scenarios we allow for the total momenta of the systems of interest to be nonzero. We also present steps towards being able to study weak processes involving two-nucleon systems, in particular we show how to determine the transition amplitude for proton-proton fusion (pp->e^+ + nu_e) directly from LQCD.

Raul A. Briceno

2013-11-23T23:59:59.000Z

46

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...

47

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

48

Baryons with strangeness and charm in a quark model with chromodynamics  

Science Journals Connector (OSTI)

The low-lying spectrum of baryons containing a charmed quark and one or two strange quarks is calculated in a a quark model with chromodynamics.

Kim Maltman and Nathan Isgur

1980-10-01T23:59:59.000Z

49

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

50

Moving nonrelativistic QCD for heavy-to-light form factors on the lattice  

SciTech Connect (OSTI)

We formulate nonrelativistic quantum chromodynamics (NRQCD) on a lattice which is boosted relative to the usual discretization frame. Moving NRQCD allows us to treat the momentum for the heavy quark arising from the frame choice exactly. We derive moving NRQCD through O(1/m{sup 2},v{sub rel}{sup 4}), as accurate as the NRQCD action in present use, both in the continuum and on the lattice with O(a{sup 4}) improvements. We have carried out extensive tests of the formalism through calculations of two-point correlators for both heavy-heavy (bottomonium) and heavy-light (B{sub s}) mesons in 2+1 flavor lattice QCD and obtained nonperturbative determinations of energy shift and external momentum renormalization. Comparison to perturbation theory at O({alpha}{sub s}) is also made. The results demonstrate the effectiveness of moving NRQCD. In particular we show that the decay constants of heavy-light and heavy-heavy mesons can be calculated with small systematic errors up to much larger momenta than with standard NRQCD.

Horgan, R. R.; Khomskii, L.; Meinel, S.; Wingate, M.; Foley, K. M.; Lepage, G. P.; Hippel, G. M. von; Hart, A.; Mueller, E. H.; Davies, C. T. H.; Dougall, A.; Wong, K. Y. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Cambridge CB3 0WA (United Kingdom); Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, New York 14853 (United States); Deutsches Elektronen-Synchroton DESY, Platanenallee 6, 15738 Zeuthen (Germany); SUPA, School of Physics and Astronomy, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ (United Kingdom); SUPA, Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2009-10-01T23:59:59.000Z

51

Hybrid Baryons in QCD  

SciTech Connect (OSTI)

We present the first comprehensive study of hybrid baryons using lattice QCD methods. Using a large basis of composite QCD interpolating fields we extract an extensive spectrum of baryon states and isolate those of hybrid character using their relatively large overlap onto operators which sample gluonic excitations. We consider the spectrum of Nucleon and Delta states at several quark masses finding a set of positive parity hybrid baryons with quantum numbers $N_{1/2^+},\\,N_{1/2^+},\\,N_{3/2^+},\\, N_{3/2^+},\\,N_{5/2^+},\\,$ and $\\Delta_{1/2^+},\\, \\Delta_{3/2^+}$ at an energy scale above the first band of `conventional' excited positive parity baryons. This pattern of states is compatible with a color octet gluonic excitation having $J^{P}=1^{+}$ as previously reported in the hybrid meson sector and with a comparable energy scale for the excitation, suggesting a common bound-state construction for hybrid mesons and baryons.

Jozef J. Dudek, Robert G. Edwards

2012-03-01T23:59:59.000Z

52

8.851 Strong Interactions, Spring 2003  

E-Print Network [OSTI]

The strong force which bind quarks together is described by a relativistic quantum field theory called quantum chromodynamics (QCD). Subject surveys: The QCD Langrangian, asymptotic freedom and deep inelastic scattering, ...

Stewart, Iain

53

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

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

QCD Phase Transitions, Volume 15  

SciTech Connect (OSTI)

The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.

Schaefer, T.; Shuryak, E.

1999-03-20T23:59:59.000Z

56

QCD, Spin-Glass and String  

E-Print Network [OSTI]

When quarks and gluons are led to form a dense medium, like in high energy or/and heavy-ion collisions, it is interesting to ask the question which are the relevant degrees of freedom that Quantum Chromodynamics predict. The present notes correspond to two lectures given at Zakopane in the (rainy) summer of 2006, where this question is adressed concretely in two cases, one in the regime of weak coupling, the other one at strong coupling. Each case corresponds to the study of a dynamically important transient phase of quarks and gluons expected to appear from Quantum Chromodynamics. In lecture I, we examine the dynamical phase space of gluon transverse momenta near the so-called ``saturation'' phase including its fluctuation pattern. In lecture II, we study the dynamics of strongly interacting gauge-theory matter (modelling quark-gluon plasma) using the AdS/CFT duality between gauge field theory at strong coupling and a gravitational background in Anti-de Sitter space.

Robi Peschanski

2006-10-02T23:59:59.000Z

57

Fermilab | Science | Questions for the Universe | The Birth of...  

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

quantum chromodynamics (QCD), the theory of the nuclear force. During the QCD phase transition, the baryonic matter in the present universe condensed from a plasma-like state of...

58

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

59

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

60

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...

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.


61

QCD Evolution Workshop: Introduction  

SciTech Connect (OSTI)

The introduction talk given at the beginning of QCD Evolution workshop held in Thomas Jefferson National Accelerator Facility (Jefferson Lab) on May 14 -17, 2012.

Alexey Prokudin

2012-12-01T23:59:59.000Z

62

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

63

QCD PHASE TRANSITIONS-VOLUME 15.  

SciTech Connect (OSTI)

The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some. efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.

SCHAFER,T.

1998-11-04T23:59:59.000Z

64

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

65

Topology in QCD  

E-Print Network [OSTI]

Topology on the lattice is reviewed. In quenched QCD topological susceptibility chi is fully understood. The Witten-Veneziano mechanism for the eta' mass is confirmed. The topological susceptibility drops to zero at the deconfining phase transition. Preliminary results are also presented for chi and chi' in full QCD, and for the spin content of the proton. The only problem there is the difficulty of the usual Hybrid Monte Carlo algorithm to bring topology to equilibrium.

G. Boyd; B. Alles; M. D'Elia; A. Di Giacomo

1997-11-13T23:59:59.000Z

66

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

67

Triangle Universities Nuclear Laboratory : 2011  

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

of Chiral effective field theories (xEFT). These theories provide a link between a low-energy description of hadrons and Quantum Chromodynamics (QCD). An important aspect of...

68

Multigrid Preconditioning for the Overlap Operator in Lattice QCD  

E-Print Network [OSTI]

The overlap operator is a lattice discretization of the Dirac operator of quantum chromodynamics, the fundamental physical theory of the strong interaction between the quarks. As opposed to other discretizations it preserves the important physical property of chiral symmetry, at the expense of requiring much more effort when solving systems with this operator. We present a preconditioning technique based on another lattice discretization, the Wilson-Dirac operator. The mathematical analysis precisely describes the effect of this preconditioning in the case that the Wilson-Dirac operator is normal. Although this is not exactly the case in realistic settings, we show that current smearing techniques indeed drive the Wilson-Dirac operator towards normality, thus providing a motivation why our preconditioner works well in computational practice. Results of numerical experiments in physically relevant settings show that our preconditioning yields accelerations of up to one order of magnitude.

Brannick, James; Kahl, Karsten; Leder, Björn; Rottmann, Matthias; Strebel, Artur

2014-01-01T23:59:59.000Z

69

Multigrid Preconditioning for the Overlap Operator in Lattice QCD  

E-Print Network [OSTI]

The overlap operator is a lattice discretization of the Dirac operator of quantum chromodynamics, the fundamental physical theory of the strong interaction between the quarks. As opposed to other discretizations it preserves the important physical property of chiral symmetry, at the expense of requiring much more effort when solving systems with this operator. We present a preconditioning technique based on another lattice discretization, the Wilson-Dirac operator. The mathematical analysis precisely describes the effect of this preconditioning in the case that the Wilson-Dirac operator is normal. Although this is not exactly the case in realistic settings, we show that current smearing techniques indeed drive the Wilson-Dirac operator towards normality, thus providing a motivation why our preconditioner works well in computational practice. Results of numerical experiments in physically relevant settings show that our preconditioning yields accelerations of up to one order of magnitude.

James Brannick; Andreas Frommer; Karsten Kahl; Björn Leder; Matthias Rottmann; Artur Strebel

2014-10-27T23:59:59.000Z

70

Phenomenological QCD equation of state for massive neutron stars  

E-Print Network [OSTI]

We construct an equation of state for massive neutron stars based on quantum chromodynamics phenomenology. Our primary purpose is to delineate the relevant ingredients of equations of state that simultaneously have the required stiffness and satisfy constraints from thermodynamics and causality. These ingredients are: (i) a repulsive density-density interaction, universal for all flavors; (ii) the color-magnetic interaction active from low to high densities; (iii) confining effects, which become increasingly important as the baryon density decreases; (iv) non-perturbative gluons, which are not very sensitive to changes of the quark density. We use the following "3-window" description: At baryon densities below about twice normal nuclear density, 2n_0, we use the Akmal-Pandharipande-Ravenhall (APR) equation of state, and at high densities, > (4-7)n_0, we use the three-flavor Nambu-Jona-Lasinio (NJL) model supplemented by vector and diquark interactions. In the transition density region, we smoothly interpolate...

Kojo, Toru; Song, Yifan; Baym, Gordon

2014-01-01T23:59:59.000Z

71

Breakdown of QCD coherence ?  

E-Print Network [OSTI]

We reconsider the calculation of a non-global QCD observable and find the possible breakdown of QCD coherence. This breakdown arises as a result of wide angle soft gluon emission developing a sensitivity to emission at small angles and it leads to the appearance of super-leading logarithms. We use the `gaps between jets' cross-section as a concrete example and illustrate that the new logarithms are intimately connected with the presence of Coulomb gluon contributions. Numerical estimates of their potential phenomenological significance are presented.

A. Kyrieleis; J. R. Forshaw; M. H. Seymour

2006-12-16T23:59:59.000Z

72

Anti-proton annihilation in nuclei as a probe of QCD  

SciTech Connect (OSTI)

Anti-proton annihilation in a nuclear target can test many novel aspects of quantum chromodynamics. In this talk I discuss a number of interesting features of such processes, including the formation of nuclear-bound quarkonium, tests of color transparency in hard, quasi-elastic nuclear reactions, higher-twist, coherent, and formation zone effects in hard inclusive nuclear reactions, reduced amplitude predictions for exclusive nuclear amplitudes, and color filter effects inclusive open and hidden charm production in nuclei. 43 refs., 6 figs., 2 tabs.

Brodsky, S.J.

1990-09-01T23:59:59.000Z

73

REGGE TRAJECTORIES IN QCD  

SciTech Connect (OSTI)

We discuss some problems concerning the application of perturbative QCD to high energy soft processes. We show that summing the contributions of the lowest twist operators for non-singlet $t$-channel leads to a Regge-like amplitude. Singlet case is also discussed.

Radyushkin, Anatoly V. [JLAB, Old Dominion U.; Efremov, Anatoly Vasilievich [Dubna, JINR; Ginzburg, Ilya F. [Novosibirsk State U.

2013-04-01T23:59:59.000Z

74

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

75

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

76

Alternative large-N limit for QCD and its implications for low-energy nuclear phenomena  

Science Journals Connector (OSTI)

The Corrigan-Ramond model for large-N QCD is analyzed in detail. The spectrum, leading-order results for interactions, and an effective Lagrangian describing large-N interactions are derived. This Lagrangian, when quantized, provides an effective quantum field theory for mesons and baryons. The applicability of such a theory to low-energy nuclear phenomena is studied. The model has features that distinguish it clearly from standard large-N QCD.

Elias B. Kiritsis and Joannis Papavassiliou

1990-12-15T23:59:59.000Z

77

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

78

Lattice QCD and NERSC requirements  

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

High temperature QCD in volumes about the size of a RHIC collision. (Bernd Berg) Field theories that might explain composite Higgs particles, and other approaches to...

79

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

80

Single spin asymmetries in QCD  

E-Print Network [OSTI]

Measurements of single transverse spin asymmetries in high energy inclusive processes have always shown unexpected and challenging results. Several cases are considered and discussed within a QCD approach which couples perturbative dynamics to new non perturbative partonic information; the aim is that of developing a consistent phenomenological description of these unusual single spin phenomena, based on a generalized QCD factorization scheme.

Mauro Anselmino

2002-01-16T23:59:59.000Z

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.


81

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

2007-01-14T23:59:59.000Z

82

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

83

New Perspectives for QCD Physics at the LHC  

E-Print Network [OSTI]

I review a number of topics where conventional wisdom relevant to hadron physics at the LHC has been challenged. For example, the initial-state and final-state interactions of the quarks and gluons entering perturbative QCD hard-scattering subprocesses lead to the breakdown of traditional concepts of factorization and universality for transverse-momentum-dependent observables at leading twist. These soft-gluon rescattering effect produce single-spin asymmetries, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as diffractive deep inelastic scattering, The antishadowing of nuclear structure functions is predicted to depend on the flavor quantum numbers of each quark and antiquark. Isolated hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation, even at the LHC. Such "direct" processes can explain the observed deviations from pQCD predictions of the power-law fall-off of inclusive hadron cross sections as well as the "baryon anomaly" seen in high-centrality heavy-ion collisions at RHIC. The intrinsic charm contribution to the proton structure function at high x can explain the large rate for high p_T photon plus charm-jet events observed at the Tevatron and imply a large production rate for charm and bottom jets at high p_T at the LHC, as well as a novel mechanism for Higgs and Z^0 production at high x_F. The light-front wavefunctions derived in AdS/QCD can be used to calculate jet hadronization at the amplitude level. The elimination of the renormalization scale ambiguity for the QCD coupling using the scheme-independent BLM method will increase the sensitivity of searches for new physics at the LHC. The implications of "in-hadron condensates" for the QCD contribution to the cosmological constant are also discussed.

Stanley J. Brodsky

2010-12-02T23:59:59.000Z

84

New Perspectives for QCD Physics at the LHC  

SciTech Connect (OSTI)

I review a number of topics where conventional wisdom relevant to hadron physics at the LHC has been challenged. For example, the initial-state and final-state interactions of the quarks and gluons entering perturbative QCD hard-scattering subprocesses lead to the breakdown of traditional concepts of factorization and universality for transverse-momentum-dependent observables at leading twist. The soft-gluon rescattering effects, which are associated with the Wilson line of the propagating partons, also lead to Bjorken-scaling single-spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung leading-twist relation in Drell-Yan reactions, as well as nuclear shadowing. The Gribov-Glauber theory applied to the antishadowing domain predicts that nuclear structure functions depend on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence recently observed in deep-inelastic neutrino scattering. Surprisingly, isolated hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation. The rate is predicted to be significant, even at the LHC. Such 'direct' processes can explain the observed deviations from perturbative QCD predictions in measurements of inclusive hadron cross sections at fixed x{sub T} = 2p{sub T}/{radical}(s), as well as the 'baryon anomaly', the anomalously large proton-to-pion ratio seen in high centrality heavy-ion collisions at RHIC. The intrinsic charm contribution to the proton structure function at high x can explain the large rate for high p{sub T} photon plus charm-jet events observed by D0 at the Tevatron. Intrinsic charm and bottom distributions also imply anomalously large production of charm and bottom jets at high p{sub T} at the LHC, as well as a novel mechanism for Higgs and Z{sup 0} production at high x{sub F}. Other novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates and the implications for the QCD contribution to the cosmological constant. The light-front wavefunctions derived in AdS/QCD can be used to calculate jet hadronization at the amplitude level. I also note that the elimination of the renormalization scale ambiguity for the QCD coupling using the scheme-independent BLM method will greatly improve the precision of QCD predictions and thus greatly increase the sensitivity of searches for new physics at the LHC.

Brodsky, S. J. [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States); CP3-Origins, Southern Denmark University, Odense (Denmark)

2011-04-26T23:59:59.000Z

85

Hot and Dense QCD Matter  

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

QCD Matter QCD Matter A Community White Paper on the Future of Relativistic Heavy-Ion Physics in the US Unraveling the Mysteries of the Strongly Interacting Quark-Gluon-Plasma Executive Summary This document presents the response of the US relativistic heavy-ion community to the request for comments by the NSAC Subcommittee, chaired by Robert Tribble, that is tasked to recommend optimizations to the US Nuclear Science Program over the next five years. The study of the properties of hot and dense QCD matter is one of the four main areas of nuclear physics research described in the 2007 NSAC Long Range Plan. The US nuclear physics community plays a leading role in this research area and has been instrumental in its most important discovery made over the past decade, namely that hot and dense QCD matter acts as a strongly interacting system with unique and previously unexpected

86

Theoretical Aspects in Perturbative QCD  

Science Journals Connector (OSTI)

The aim of this set of lectures is to provide an impressionistic view of the current research activity in the field of perturbative QCD 1) by discussing a selection of topics which in a way or another are of part...

G. Altarelli

1982-01-01T23:59:59.000Z

87

Recent Developments in Perturbative QCD  

Science Journals Connector (OSTI)

In these lectures I review some of the recent theoretical developments of the applications of perturbative QCD to hard scattering processes which can be studied at the present and future high energy e+e-, e?p, pp...

Z. Kunszt

1990-01-01T23:59:59.000Z

88

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

89

Generalized Parton Distributions from Lattice QCD  

E-Print Network [OSTI]

I review the LHPC Collaboration's lattice QCD calculations of the generalized parton distributions of the nucleon and highlight those aspects of nucleon structure best illuminated by lattice QCD, the nucleon's spin decomposition and transverse quark structure.

D. B. Renner

2005-01-05T23:59:59.000Z

90

Understanding Parton Distributions from Lattice QCD  

E-Print Network [OSTI]

I examine the past lattice QCD calculations of three representative observables, the transverse quark distribution, momentum fraction, and axial charge, and emphasize the prospects for not only quantitative comparison with experiment but also qualitative understanding of QCD.

Dru B. Renner

2005-08-04T23:59:59.000Z

91

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

92

QCD physics at tevatron and LHC  

Science Journals Connector (OSTI)

Presented are the Tevatron Run I QCD results that have been known for the degree of controversy associated with them. Also, the prospects for the QCD-motivated studies at Tevatron Run II and LHC are briefly discu...

A. Korytov

2004-01-01T23:59:59.000Z

93

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

94

Hadron Structure from Lattice QCD  

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

Lattice QCD in Nuclear Physics Lattice QCD in Nuclear Physics Robert Edwards Jefferson Lab NERSC 2011 Report: Robert Edwards, Martin Savage & Chip Watson Current HPC Methods * Algorithms - Gauge generation - Analysis phase * Codes - USQCD SciDAC codes - Heavily used at NERSC: QDP++ & Chroma * Quantities that affect the scale of the simulations - Lattice size, lattice spacing & pion mass Gauge generation Hybrid Monte Carlo (HMC) * Hamiltonian integrator: 1 st order coupled PDE's * Large, sparse, matrix solve per step * "Configurations" via importance sampling * Use Metropolis method * Produce ~1000 useful configurations in a dataset Cost: * Controlled by lattice size & spacing, quark mass * Requires capability resources

95

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

96

Color correlations in QCD plasma  

Science Journals Connector (OSTI)

Perturbative QCD and the random-phase approximation are used to study the current-current correlation function in quark-gluon plasma. The calculations show that there are damped collective oscillations in the system. An estimate of the Debye screening length gives a value of about 0.5 fm at a temperature of 250 MeV.

Jitendra C. Parikh and Philip J. Siemens

1988-06-01T23:59:59.000Z

97

Two Flavour QCD Phase Transition  

E-Print Network [OSTI]

Results on the phase transition in QCD with two flavours of light staggered fermions from an ongoing simulation are presented. We find the restoration of the chiral SU(2) x SU(2) symmetry, but not of the axial U_A(1) symmetry.

G. Boyd; F. Karsch; E. Laermann; M. Oevers

1996-07-20T23:59:59.000Z

98

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

99

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

100

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

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

Fate of QCD sum rules or fate of vector meson dominance in a nuclear medium  

E-Print Network [OSTI]

A current-current correlator with the quantum numbers of the omega meson is studied in a nuclear medium. Using weighted finite energy sum rules and dispersion relations for the current-nucleon forward scattering amplitude it is shown that strict vector meson dominance and QCD sum rules are incompatible with each other. This implies that at least one of these concepts -- which are both very powerful in the vacuum -- has to fade in the nuclear environment.

Stefan Leupold

2006-04-06T23:59:59.000Z

102

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

103

Effective Hamiltonians for generalized Breit interactions in QCD  

Science Journals Connector (OSTI)

Effective Hamiltonians for two-body interactions consistent with Lorentz covariance to order v2/c2 are obtained by reducing the instantaneous Bethe-Salpeter equation and the two-body Dirac equation to Schrödinger-Pauli form by the large-component method of reduction. Previous calculations of effective Hamiltonians for scalar exchange are shown to be incomplete. They omit generalized Breit interactions which are required for a general description of scalar exchange in both classical and quantum field theory. The effective Hamiltonians are obtained for arbitrary potential functions to facilitate their use in QCD calculations. The ambiguity that is present in the more common type of derivation based on a covariant decomposition of the Bethe-Salpeter kernel in momentum space is avoided in this approach.

R. W. Childers

1987-07-15T23:59:59.000Z

104

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

105

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

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

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

108

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

109

Simplifying Multi-Jet QCD Computation  

SciTech Connect (OSTI)

These lectures give a pedagogical discussion of the computation of QCD tree amplitudes for collider physics. The tools reviewed are spinor products, color ordering, MHV amplitudes, and the Britto-Cachazo-Feng-Witten recursion formula.

Peskin, Michael E.; /SLAC

2011-11-04T23:59:59.000Z

110

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

111

Some New/Old Approaches to QCD  

DOE R&D Accomplishments [OSTI]

In this lecture I shall discuss some recent attempts to revive some old ideas to address the problem of solving QCD. I believe that it is timely to return to this problem which has been woefully neglected for the last decade. QCD is a permanent part of the theoretical landscape and eventually we will have to develop analytic tools for dealing with the theory in the infra-red. Lattice techniques are useful but they have not yet lived up to their promise. Even if one manages to derive the hadronic spectrum numerically, to an accuracy of 10% or even 1%, we will not be truly satisfied unless we have some analytic understanding of the results. Also, lattice Monte-Carlo methods can only be used to answer a small set of questions. Many issues of great conceptual and practical interest-in particular the calculation of scattering amplitudes, are thus far beyond lattice control. Any progress in controlling QCD in an explicit analytic, fashion would be of great conceptual value. It would also be of great practical aid to experimentalists, who must use rather ad-hoc and primitive models of QCD scattering amplitudes to estimate the backgrounds to interesting new physics. I will discuss an attempt to derive a string representation of QCD and a revival of the large N approach to QCD. Both of these ideas have a long history, many theorist-years have been devoted to their pursuit-so far with little success. I believe that it is time to try again. In part this is because of the progress in the last few years in string theory. Our increased understanding of string theory should make the attempt to discover a stringy representation of QCD easier, and the methods explored in matrix models might be employed to study the large N limit of QCD.

Gross, D. J.

1992-11-00T23:59:59.000Z

112

QCD and Hard Diffraction at the LHC  

E-Print Network [OSTI]

As an introduction to QCD at the LHC I give an overview of QCD at the Tevatron, emphasizing the high Q^2 frontier which will be taken over by the LHC. After describing briefly the LHC detectors I discuss high mass diffraction, in particular central exclusive production of Higgs and vector boson pairs. I introduce the FP420 project to measure the scattered protons 420m downstream of ATLAS and CMS.

Michael G. Albrow

2005-09-26T23:59:59.000Z

113

Fundamental Physics with Cold Neutrons J. S. Nico,1  

E-Print Network [OSTI]

Fundamental Physics with Cold Neutrons J. S. Nico,1 G. L. Greene,2 F. E. Wietfeldt,3 and W. S physics and quantum chromodynamics (QCD). Low energy properties of nucleons and nuclei, such as weak interactions in n-A systems, low energy n-A scattering amplitudes, and the internal electro- magnetic structure

114

Determinations of the QCD strong coupling ?s and the scale ?QCD  

Science Journals Connector (OSTI)

We review determinations, via experiment, of the strong coupling of QCD, ?s. In almost every case we use the results of perturbative QCD to make the necessary extraction from data. These include scaling violations of deep inelastic scattering, e+e- annihilation experiments (including quarkonium decays) and lepton pair production. Finally estimates for ? from lattice calculations are listed.

D.W. Duke; R.G. Roberts

1985-01-01T23:59:59.000Z

115

Quantum Privacy and Quantum Coherence  

Science Journals Connector (OSTI)

We derive a simple relation between a quantum channel's capacity to convey coherent (quantum) information and its usefulness for quantum cryptography.

Benjamin Schumacher and Michael D. Westmoreland

1998-06-22T23:59:59.000Z

116

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

117

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

118

Highlights from LHC experiments and future perspectives  

E-Print Network [OSTI]

The experiments at LHC are collecting a large amount of data in a kinematic of the $(x, Q^2)$ variables never accessed before. Boosted by LHC analyses, Quantum Chromodynamics (QCD) is experiencing an impressive progress in the last few years, and even brighter perspectives can be foreseen for the future data taking. A subset of the most recent results from the LHC experiments in the area of QCD (both perturbative and soft) are reviewed.

Campana, Pierluigi

2014-01-01T23:59:59.000Z

119

Glimpsing Colour in a World of Black and White  

SciTech Connect (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.

Michael Pennington

2012-09-01T23:59:59.000Z

120

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

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

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

122

Mathematica and Fortran programs for various analytic QCD couplings  

E-Print Network [OSTI]

We outline here the motivation for the existence of analytic QCD models, i.e., QCD frameworks in which the running coupling $A(Q^2)$ has no Landau singularities. The analytic (holomorphic) coupling $A(Q^2)$ is the analog of the underlying pQCD coupling $a(Q^2) \\equiv \\alpha_s(Q^2)/\\pi$, and any such $A(Q^2)$ defines an analytic QCD model. We present the general construction procedure for the couplings $A_{\

Cesar Ayala; Gorazd Cvetic

2014-11-06T23:59:59.000Z

123

Mathematica and Fortran programs for various analytic QCD couplings  

E-Print Network [OSTI]

We outline here the motivation for the existence of analytic QCD models, i.e., QCD frameworks in which the running coupling $A(Q^2)$ has no Landau singularities. The analytic (holomorphic) coupling $A(Q^2)$ is the analog of the underlying pQCD coupling $a(Q^2) \\equiv \\alpha_s(Q^2)/\\pi$, and any such $A(Q^2)$ defines an analytic QCD model. We present the general construction procedure for the couplings $A_{\

Ayala, Cesar

2014-01-01T23:59:59.000Z

124

The Two-Loop Scale Dependence of the Static QCD Potential including Quark Masses  

SciTech Connect (OSTI)

The interaction potential V(Q{sup 2}) between static test charges can be used to define an effective charge {alpha}{sub V}(Q{sup 2}) and a physically-based renormalization scheme for quantum chromodynamics and other gauge theories. In this paper we use recent results for the finite-mass fermionic corrections to the heavy-quark potential at two-loops to derive the next-to-leading order term for the Gell Mann-Low function of the V-scheme. The resulting effective number of flavors N{sub F}(Q{sup 2}/m{sup 2}) in the {alpha}{sub V} scheme is determined as a gauge-independent and analytic function of the ratio of the momentum transfer to the quark pole mass. The results give automatic decoupling of heavy quarks and are independent of the renormalization procedure. Commensurate scale relations then provide the next-to-leading order connection between all perturbatively calculable observables to the analytic and gauge-invariant {alpha}{sub V} scheme without any scale ambiguity and a well defined number of active flavors. The inclusion of the finite quark mass effects in the running of the coupling is compared with the standard treatment of finite quark mass effects in the {ovr MS} scheme.

Brodsky, Stanley J.

1999-06-14T23:59:59.000Z

125

Are There Tetraquarks at Large $N_c$ in QCD(F)?  

E-Print Network [OSTI]

Weinberg recently pointed out a flaw in the standard argument that large $N_c$ QCD with color-fundamental quarks [QCD(F)] cannot yield narrow tetraquark states. In particular, he observed that the argument does not rule out narrow tetraquarks associated with the leading-order connected diagrams; such tetraquarks would have a width scaling as $N_c^{-1}$. It is shown here, however, that while the standard analysis of tetraquarks does not rule them out, a more thorough analysis rules out quantum-number exotic tetraquarks associated with the leading-order connected diagrams. This analysis is based entirely on conventional assumptions used in large $N_c$ physics applied to the analytic properties of meson-meson scattering. Our result implies that one of three possibilities must be true: i) quantum-number exotic tetraquarks do not exist at large $N_c$; ii) quantum-number exotic tetraquarks exist, but are associated with subleading connected diagrams and have anomalously small widths that scale as $N_c^{-2}$ or smal...

Cohen, Thomas D

2014-01-01T23:59:59.000Z

126

Are There Tetraquarks at Large $N_c$ in QCD(F)?  

E-Print Network [OSTI]

Weinberg recently pointed out a flaw in the standard argument that large $N_c$ QCD with color-fundamental quarks [QCD(F)] cannot yield narrow tetraquark states. In particular, he observed that the argument does not rule out narrow tetraquarks associated with the leading-order connected diagrams; such tetraquarks would have a width scaling as $N_c^{-1}$. It is shown here, however, that while the standard analysis of tetraquarks does not rule them out, a more thorough analysis rules out quantum-number exotic tetraquarks associated with the leading-order connected diagrams. This analysis is based entirely on conventional assumptions used in large $N_c$ physics applied to the analytic properties of meson-meson scattering. Our result implies that one of three possibilities must be true: i) quantum-number exotic tetraquarks do not exist at large $N_c$; ii) quantum-number exotic tetraquarks exist, but are associated with subleading connected diagrams and have anomalously small widths that scale as $N_c^{-2}$ or smaller; or iii) the conventional assumptions used in large $N_c$ analysis are inadequate.

Thomas D. Cohen; Richard F. Lebed

2014-03-31T23:59:59.000Z

127

Equation of State from Lattice QCD Calculations  

SciTech Connect (OSTI)

We provide a status report on the calculation of the Equation of State (EoS) of QCD at finite temperature using lattice QCD. Most of the discussion will focus on comparison of recent results obtained by the HotQCD and Wuppertal-Budapest collaborations. We will show that very significant progress has been made towards obtaining high precision results over the temperature range of T = 150-700 MeV. The various sources of systematic uncertainties will be discussed and the differences between the two calculations highlighted. Our final conclusion is that these lattice results of EoS are precise enough to be used in the phenomenological analysis of heavy ion experiments at RHIC and LHC.

Gupta, Rajan [Los Alamos National Laboratory

2011-01-01T23:59:59.000Z

128

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

129

Quantum Tetrahedra  

E-Print Network [OSTI]

We discuss in details the role of Wigner 6j symbol as the basic building block unifying such different fields as state sum models for quantum geometry, topological quantum field theory, statistical lattice models and quantum computing. The apparent twofold nature of the 6j symbol displayed in quantum field theory and quantum computing -a quantum tetrahedron and a computational gate- is shown to merge together in a unified quantum-computational SU(2)-state sum framework.

Mauro Carfora; Annalisa Marzuoli; Mario Rasetti

2010-01-25T23:59:59.000Z

130

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

131

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

2011-03-03T23:59:59.000Z

132

Proton Spin Structure from Lattice QCD  

Science Journals Connector (OSTI)

A lattice QCD calculation of the proton matrix element of the flavor singlet axial-vector current is reported. Both the connected and disconnected contributions are calculated, for the latter employing the variant method of wall source without gauge fixing. From simulations in quenched QCD with the Wilson quark action on a 163×20 lattice at ?=5.7 (the lattice spacing a?0.14 fm), we find ??=?u+?d+?s=+0.63854-0.34746-0.10930=+0.1810 with the disconnected contribution to ?u and ?d equal to -0.11944, which is reasonably consistent with the experiment.

M. Fukugita; Y. Kuramashi; M. Okawa; A. Ukawa

1995-09-11T23:59:59.000Z

133

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

134

Quantum correlation via quantum coherence  

E-Print Network [OSTI]

Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes of quantum coherence. We propose a revised measure for total coherence and find that this measure can lead to a symmetric version of geometric quantum correlation which is analytic for two qubits. In particular, this measure can also arrive at a monogamy equality on the distribution of quantum coherence. Finally, we also quantify a remaining type of quantum coherence and find that for two qubits it is directly connected with quantum nonlocality.

Chang-shui Yu; Yang Zhang; Haiqing Zhao

2014-02-19T23:59:59.000Z

135

Parton Distributions and QCD at LHCb  

E-Print Network [OSTI]

We consider the impact that can be made on our understanding of parton distributions (PDFs) and QCD from early measurements at the LHCb experiment. The high rapidity values make the experiment uniquely suited to a detailed study of small-x parton distributions and hence will make a significant contribution towards the clarification of both experimental and theoretical uncertainties on PDFs and their applications.

Thorne, R S; Stirling, W J; Watt, G

2008-01-01T23:59:59.000Z

136

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

137

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

138

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

139

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

140

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

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

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

2012-04-18T23:59:59.000Z

142

The Top Quark, QCD, And New Physics.  

DOE R&D Accomplishments [OSTI]

The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup+}e{sup -}+ t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup+}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

Dawson, S.

2002-06-00T23:59:59.000Z

143

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

144

A QCD analysis of ZEUS diffractive data  

E-Print Network [OSTI]

ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to costrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data.

ZEUS Collaboration

2009-11-23T23:59:59.000Z

145

Semiclassical string spectrum in a string model dual to large N QCD  

Science Journals Connector (OSTI)

We explore the string spectrum in the Witten QCD 4 model by considering classical string configurations, thereby obtaining energy formulas for quantum states with large excitation quantum numbers representing glueballs and Kaluza–Klein states. In units of the string tension, the energies of all states increase as the 't Hooft coupling ? is decreased, except the energies of glueballs corresponding to strings lying on the horizon, which remain constant. We argue that some string solutions can be extrapolated to the small ? regime. We also find the classical mechanics description of supergravity glueballs in terms of point-like string configurations oscillating in the radial direction, and reproduce the glueball energy formula previously obtained by solving the equation for the dilaton fluctuation.

J.M. Pons; J.G. Russo; P. Talavera

2004-01-01T23:59:59.000Z

146

Quantum Institute  

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

Quantum Institute Quantum Institute Quantum Institute A new research frontier awaits! Our door is open and we thrive on mutually beneficial partnerships, collaborations that drive innovations and new technologies. Contact Leader Malcolm Boshier (505) 665-8892 Email Two of LANL's most successful quantum technology initiatives: quantum cryptography and the race for quantum computer The area of quantum information, science, and technology is rapidly evolving, with important applications in the areas of quantum cryptography, quantum computing, quantum metrology, and advanced quantum-based sensors, some of which are directly relevant to the Laboratory's national security mission. Mission Foster a vigorous intellectual environment at LANL Define and develop strategic thrusts Target and pursue funding opportunities

147

Quantum discord  

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

Quantum discord Quantum discord 1663 Los Alamos science and technology magazine Latest Issue:November 2013 All Issues » submit Quantum discord A distinguishing aspect of quantum mechanics discovered at Los Alamos that may be critical to building a quantum computer March 25, 2013 Spinning coins turning into binary numbers Quantum computing Quantum computing can be carried out without the delicate entanglement of qubits previously believed to be necessary Quantum computing, in which quantum bits of information (or qubits) juggle a "superposition" of multiple values simultaneously, offers to unleash tremendous computational power if the qubits can be effectively isolated to prevent decoherence: information describing quantum states dispersing into the environment. But recent research has shown that quantum computing can be carried out

148

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

149

Probing the QCD phase diagram with fluctuations  

E-Print Network [OSTI]

The relevance of higher order cumulants of conserved charges for the analysis of freeze-out and critical conditions in heavy ion collisions at LHC and RHIC is discussed. Using properties of $O(4)$ scaling functions, the generic structure of these higher cumulants at vanishing baryon chemical potential is discussed. Chiral model calculations are then used to study their properties at non-zero baryon chemical potential. It is argued that the rapid variation of sixth and higher order cumulants at the phase boundary may be used to explore the QCD phase diagram in experiment. Moreover, results for the Polyakov loop susceptibilities in SU(3) lattice gauge theory as well as in (2+1) flavor lattice QCD are discussed. An analysis of the ratios of susceptibilities indicates that the deconfinement transition is reflected in characteristic modifications of these ratios.

Friman, Bengt

2014-01-01T23:59:59.000Z

150

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

151

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

152

Summary of low-energy aspects of QCD and medium-energy hadron parallel sessions  

SciTech Connect (OSTI)

Two sessions were organized dealing with low energy aspects of QCD. The first dealt with the issue of QCD dibaryons. The second session centered on mostly low-energy tests of QCD. This report discusses experiments dealing with these sessions.

McClelland, J.B.

1991-01-01T23:59:59.000Z

153

Kaon pictures of QCD plasma droplets  

Science Journals Connector (OSTI)

We demonstrate that emission of bosons from a dispersed collection of droplets will produce a two-tiered correlation function reflecting the size of the droplets as well as their spatial distribution. We argue that this two-tiered correlation can signal the existence of a mixed phase of QCD plasma and hadronic gas in relativistic nuclear collisions, and propose that positive kaons will be the best indicators of this structure.

Scott Pratt; Philip J. Siemens; Axel P. Vischer

1992-02-24T23:59:59.000Z

154

Diffractive parton distributions from perturbative QCD  

E-Print Network [OSTI]

The asymptotic collinear factorisation theorem, which holds for diffractive deep-inelastic scattering, has important modifications in the sub-asymptotic HERA regime. We use perturbative QCD to quantify these modifications. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation. We emphasise that it is necessary to include both the gluonic and sea-quark t-channel components of the perturbative Pomeron. The corresponding Pomeron-to-parton splitting functions are derived in the Appendix.

Martin, A D; Watt, G

2005-01-01T23:59:59.000Z

155

Diffractive parton distributions from perturbative QCD  

E-Print Network [OSTI]

The asymptotic collinear factorisation theorem, which holds for diffractive deep-inelastic scattering, has important modifications in the sub-asymptotic HERA regime. We use perturbative QCD to quantify these modifications. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation. We emphasise that it is necessary to include both the gluonic and sea-quark t-channel components of the perturbative Pomeron. The corresponding Pomeron-to-parton splitting functions are derived in the Appendix.

A. D. Martin; M. G. Ryskin; G. Watt

2005-04-15T23:59:59.000Z

156

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

157

Decorrelating the topology in full QCD  

E-Print Network [OSTI]

We investigate the performance of the hybrid Monte Carlo algorithm in updating non-trivial global topological structures. We find that the hybrid Monte Carlo algorithm has serious problems decorrelating the global topological charge. This represents a warning which must be seriously considered when simulating full QCD, regardless of the number and type of fermions, with this or any similar algorithm. Simulated tempering is examined as a means of accelerating the decorrelation.

G. Boyd; B. Allés; M. D'Elia; A. Di Giacomo; E. Vicari

1996-08-22T23:59:59.000Z

158

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

159

lqcd.dvi  

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

Lattice Lattice QCD 1 1. LATTICE QUANTUM CHROMODYNAMICS Updated September 2013 by S. Hashimoto (KEK), J. Laiho (Syracuse University) and S.R. Sharpe (University of Washington). 1.1. Lattice regularization of QCD Gauge theories form the building blocks of the Standard Model. While the SU(2) and U(1) parts have weak couplings and can be studied accurately with perturbative methods, the SU(3) component-QCD-is only amenable to a perturbative treatment at high energies. The growth of the coupling constant in the infrared-the flip-side of asymptotic freedom-requires the use of non-perturbative methods to determine the low energy properties of QCD. Lattice gauge theory, proposed by K. Wilson in 1974 [1], provides such a method, for it gives a non-perturbative definition of vector-like gauge field theories like QCD. In lattice regularized QCD-commonly called lattice QCD or LQCD-Euclidean

160

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

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.


161

QCD at non-zero temperature and magnetic field  

E-Print Network [OSTI]

A status of lattice QCD thermodynamics, as of 2013, is summarized. Only bulk thermodynamics is considered. There is a separate section on magnetic fields.

Kalman Szabo

2014-01-16T23:59:59.000Z

162

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

163

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

164

Quantum fluctuations of axions  

SciTech Connect (OSTI)

We study the time evolution of the quantum fluctuations of the axion field for both the QCD axion as well as axions arising in the context of supergravity and string theories. We explicitly keep track not only of the coherently oscillating zero momentum mode of the axion but also of the higher non-zero momentum modes using the full axion potential. The full axion potential makes possible two kinds of instabilities: spinodal instabilities and parametric resonance instabilities. The presence of either of these instabilities can lead to a quasi-exponential increase in the occupation of non-zero momentum modes and the build-up of the quantum fluctuations of the axions. If either of these becomes a significant effect then axions would no longer be a suitable cold dark matter candidate. Our results confirm the conventional wisdom that these effects are not significant in the setting of an expanding FRW universe and hence axions are indeed cold dark matter candidates. {copyright} {ital 1998} {ital The American Physical Society}

Kolb, E.W. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)] [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); [Department of Astronomy and Astrophysics, Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Singh, A.; Srednicki, M. [Department of Physics, University of California, Santa Barbara, California 93106 (United States)] [Department of Physics, University of California, Santa Barbara, California 93106 (United States)

1998-11-01T23:59:59.000Z

165

A next-to-leading-order QCD analysis of neutrino-iron structure functions at the Tevatron  

SciTech Connect (OSTI)

Nucleon structure functions measured in neutrino-iron and antineutrino-iron charged-current interactions are presented. The data were taken in two high-energy high-statistics runs by the LAB-E detector at the Fermilab Tevatron. Structure functions are extracted from a sample of 950,000 neutrino and 170,000 antineutrino events with neutrino energies from 30 to 360 GeV. The structure functions F{sub 2} and xF{sub 3} are compared with the predictions of perturbative Quantum Chromodynamics (PQCD). The combined non-singlet and singlet evolution in the context of PQCD gives value of {Lambda}NLO,(4)/MS = 337 {+-} 28 (exp.) MeV, which corresponds to {alpha}{sub S}(M{sub Z}{sup 2}) = 0.119 {+-} 0.002 (exp.) {+-} 0.004 (theory), and with a gluon distribution given by xG(x,Q{sub 0}{sup 2} = 5GeV{sup 2}) = (2.22 {+-} 0.34) {times} (1 {minus} x){sup 4.65{+-}0.68}.

Seligman, W.G.

1997-06-01T23:59:59.000Z

166

The CP-PACS Project and Lattice QCD Results  

Science Journals Connector (OSTI)

......April 2000 research-article Articles The CP-PACS Project and Lattice QCD Results Yoichi...Tsukuba 305-0006, Japan The aim of the CP-PACS project was to develop a massively...with primary emphasis on lattice QCD. The CP-PACS computer with a peak speed of 614......

Yoichi Iwasaki

2000-04-01T23:59:59.000Z

167

Visualization of semileptonic form factors from lattice QCD  

SciTech Connect (OSTI)

Comparisons of lattice-QCD calculations of semileptonic form factors with experimental measurements often display two sets of points, one each for lattice QCD and experiment. Here we propose to display the output of a lattice-QCD analysis as a curve and error band. This is justified, because lattice-QCD results rely in part on fitting, both for the chiral extrapolation and to extend lattice-QCD data over the full physically allowed kinematic domain. To display an error band, correlations in the fit parameters must be taken into account. For the statistical error, the correlation comes from the fit. To illustrate how to address correlations in the systematic errors, we use the Becirevic-Kaidalov parametrization of the D{yields}{pi}l{nu} and D{yields}Kl{nu} form factors, and an analyticity-based fit for the B{yields}{pi}l{nu} form factor f{sub +}.

Bernard, C.; Laiho, J. [Department of Physics, Washington University, St. Louis, Missouri (United States); DeTar, C.; Levkova, L.; Oktay, M. B. [Physics Department, University of Utah, Salt Lake City, Utah (United States); Di Pierro, M. [School of Computer Science, Telecommunications and Information Systems, DePaul University, Chicago, Illinois (United States); El-Khadra, A. X.; Evans, R. T.; Gamiz, E. [Physics Department, University of Illinois, Urbana, Illinois (United States); Freeland, E. D. [Liberal Arts Department, The School of the Art Institute of Chicago, Chicago, Illinois (United States); Gottlieb, Steven [Department of Physics, Indiana University, Bloomington, Indiana (United States); Heller, U. M. [American Physical Society, Ridge, New York (United States); Hetrick, J. E. [Physics Department, University of the Pacific, Stockton, California (United States); Kronfeld, A. S.; Mackenzie, P. B.; Okamoto, M.; Simone, J. N. [Fermi National Accelerator Laboratory, Batavia, Illinois (United States); Sugar, R. [Department of Physics, University of California, Santa Barbara, California (United States); Toussaint, D. [Department of Physics, University of Arizona, Tucson, Arizona (United States); Van de Water, R. S. [Physics Department, Brookhaven National Laboratory, Upton, New York (United States)

2009-08-01T23:59:59.000Z

168

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

169

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

170

Axial nucleon form factors from lattice QCD  

SciTech Connect (OSTI)

We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length L=2.1 fm and L=2.8 fm. Cut-off effects are investigated using three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm. The nucleon axial charge is obtained in the continuum limit and chirally extrapolated to the physical pion mass enabling comparison with experiment.

Alexandrou, C. [Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Computation-based Science and Technology Research Center, Cyprus Institute, 20 Kavafi Str., Nicosia 2121 (Cyprus); Brinet, M.; Carbonell, J.; Harraud, P. A.; Papinutto, M. [Laboratoire de Physique Subatomique et Cosmologie, UJF/CNRS/IN2P3, 53 avenue des Martyrs, 38026 Grenoble (France); Constantinou, M. [Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Guichon, P. [CEA-Saclay, IRFU/Service de Physique Nucleaire, 91191 Gif-sur-Yvette (France); Jansen, K. [NIC, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Korzec, T. [Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Institut fuer Physik Humboldt Universitaet zu Berlin, Newtonstrasse 15, 12489 Berlin (Germany)

2011-02-15T23:59:59.000Z

171

I, Quantum Robot: Quantum Mind control on a Quantum Computer  

E-Print Network [OSTI]

The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be the use of coherent states in brain signals.

Paola Zizzi

2008-12-25T23:59:59.000Z

172

A multiplexed quantum memory  

Science Journals Connector (OSTI)

A quantum repeater is a system for long-distance quantum communication that employs quantum memory elements to mitigate optical fiber transmission losses. The multiplexed quantum...

Lan, S -Y; Radnaev, A G; Collins, O A; Matsukevich, D N; Kennedy, T A; Kuzmich, A

2009-01-01T23:59:59.000Z

173

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

174

Electron Ion Collider: The Next QCD Frontier  

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

Ion Collider: Ion Collider: The Next QCD Frontier Understanding the glue that binds us all Electron Ion Collider: The Next QCD Frontier Understanding the glue that binds us all BNL-98815-2012-JA JLAB-PHY-12-1652 arXiv:1212.1701 Authors A. Accardi 14,28 , J. L. Albacete 16 , M. Anselmino 29 , N. Armesto 36 , E. C. Aschenauer 3,† , A. Bacchetta 35 , D. Boer 33 , W. Brooks 37,† , T. Burton 3 , N.-B. Chang 23 , W.-T. Deng 13,23 , A. Deshpande 25,∗,† , M. Diehl 11,† , A. Dumitru 2 , R. Dupr´ e 7 , R. Ent 28,‡ , S. Fazio 3 , H. Gao 12,† , V. Guzey 28 , H. Hakobyan 37 , Y. Hao 3 , D. Hasch 15 , R. Holt 1,† , T. Horn 5,† , M. Huang 23 , A. Hutton 28,† , C. Hyde 20 , J. Jalilian-Marian 2 , S. Klein 17 , B. Kopeliovich 37 , Y. Kovchegov 19,† , K. Kumar 24,† , K. Kumeriˇ cki 40 , M. A. C. Lamont 3 , T. Lappi 34 , J.-H. Lee 3 , Y. Lee 3 , E. M. Levin 26,37 , F.-L. Lin 28 , V. Litvinenko 3 , T. W. Ludlam 3,‡ , C. Marquet

175

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

176

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

177

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

178

QCD in magnetic fields: from Hofstadter's butterfly to the phase diagram  

E-Print Network [OSTI]

I revisit the problem of a charged particle on a two-dimensional lattice immersed in a constant (electro)magnetic field, and discuss the energy spectrum - Hofstadter's butterfly - from a new, quantum field theoretical perspective. In particular, I point out that there is an intricate interplay between a) the structure of the butterfly at low magnetic flux, b) the absence of asymptotic freedom in QED and c) the enhancement of the quark condensate by a magnetic field at zero temperature. I proceed to discuss the response of the QCD condensate to the magnetic field at nonzero temperatures in four space-time dimensions, present the resulting phase diagram and compare it to low-energy model predictions.

Endrodi, G

2014-01-01T23:59:59.000Z

179

Equation of State of Nucleon Matters from Lattice QCD Simulations  

E-Print Network [OSTI]

Nucleon matters are studied based on QCD. We extract nucleon-nucleon interaction from lattice QCD simulations in a recently developed approach, and then derive the equations of state of the symmetric nuclear matter and the pure neutron matter, at zero temperature, in the Brueckner-Hartree-Fock framework. We find that QCD reproduce known features of the symmetric nuclear matter, such as the self-binding and saturation, at some values of quark mass. We find also that the pure neutron matter become more stiff at large density as quark mass decrease. We apply these equations of state to neutron star and study its mass and radius.

Takashi Inoue; for HAL QCD Collaboration

2013-11-25T23:59:59.000Z

180

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

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

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

182

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

183

Color Magnetic Flux Tubes in Dense QCD  

E-Print Network [OSTI]

QCD is expected to be in the color-flavor locking phase in high baryon density, which exhibits color superconductivity. The most fundamental topological objects in the color superconductor are non-Abelian vortices which are topologically stable color magnetic flux tubes. We present numerical solutions of the color magnetic flux tube for diverse choices of the coupling constants. We also analytically study its asymptotic profiles and find that they are different from the case of usual superconductors. We propose the width of color magnetic fluxes and find that it is larger than naive expectation of the Compton wave length of the massive gluon when the gluon mass is larger than the scalar mass.

Minoru Eto; Muneto Nitta

2009-07-07T23:59:59.000Z

184

Color magnetic flux tubes in dense QCD  

SciTech Connect (OSTI)

QCD is expected to be in the color-flavor locking phase in high baryon density, which exhibits color superconductivity. The most fundamental topological objects in the color superconductor are non-Abelian vortices which are topologically stable color magnetic flux tubes. We present numerical solutions of the color magnetic flux tube for diverse choices of the coupling constants based on the Ginzburg-Landau Lagrangian. We also analytically study its asymptotic profiles and find that they are different from the case of usual superconductors. We propose the width of color magnetic fluxes and find that it is larger than naive expectation of the Compton wavelength of the massive gluon when the gluon mass is larger than the scalar mass.

Eto, Minoru [Theoretical Physics Laboratory, RIKEN, Saitama 351-0198 (Japan); Nitta, Muneto [Department of Physics, and Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan)

2009-12-15T23:59:59.000Z

185

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

186

Strong decays of excited baryons in Large Nc QCD  

SciTech Connect (OSTI)

We present the analysis of the strong decays 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.

Goity, J. L. [Physics Dept., Hampton University, Hampton, VA 23668 (United States); TJNAF, Newport News, VA 23606 (United States); Scoccola, N. N. [Lab. TANDAR, CNEA, Av.Libertador 8250, 1429 Buenos Aires (Argentina); CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Universidad Favaloro, Solis 453, 1078 Buenos Aires (Argentina)

2007-02-12T23:59:59.000Z

187

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

188

The spin content of the proton in full QCD  

E-Print Network [OSTI]

We present preliminary results on the proton spin structure function in full QCD. The measurement has been done using 4 flavours of staggered fermions and an improved definition of the lattice topological charge density.

B. Alles; G. Boyd; M. D'Elia; A. Di Giacomo

1997-09-21T23:59:59.000Z

189

QCD Thermodynamics at High Temperature Peter Petreczky Large...  

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

RBC (HEP) DWF thermo BNL (NP) HotQCD LLNL DWF and staggered thermo Bielefeld University,Germany Wuhan University Resource in 2013-2014 (in core h): 1) CPU clusters of USQCD: 40M...

190

Charm and bottom hadronic form factors with QCD sum rules  

SciTech Connect (OSTI)

We present a brief review of some calculations of form factors and coupling constants in vertices with charm and bottom mesons in the framework of QCD sum rules. We first discuss the motivation for this work, describing possible applications of these form factors to charm and bottom decays processes. We first make a summarize of the QCD sum rules method. We give special attention to the uncertainties of the method introducing by the intrinsic variation of the parameters. Finally we conclude.

Bracco, M. E. [Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Rod. Presidente Dutra Km 298, Polo Industrial, 27537-000, Resende, RJ (Brazil); Rodrigues, B. O.; Cerqueira, A. Jr. [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, 20550-900, Rio de Janeiro, RJ (Brazil)

2013-03-25T23:59:59.000Z

191

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

192

Hybrid Monte Carlo and topological modes of full QCD  

E-Print Network [OSTI]

We investigate the performance of the hybrid Monte Carlo algorithm, the standard algorithm used for lattice QCD simulations involving fermions, in updating non-trivial global topological structures. We find that the hybrid Monte Carlo algorithm has serious problems decorrelating the global topological charge at the values of $\\beta$ and $m$ currently simulated, where continuum physics should be approximately realized. This represents a warning which must be seriously considered when simulating full QCD by hybrid Monte Carlo.

B. Allés; G. Boyd; M. D'Elia; A. Di Giacomo; E. Vicari

1996-07-22T23:59:59.000Z

193

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

194

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

195

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

196

quarkmod.dvi  

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

August August 2011 by C. Amsler (University of Z¨ urich), T. DeGrand (University of Colorado, Boulder), and B. Krusche (University of Basel). 1.1. Quantum numbers of the quarks Quantum chromodynamics (QCD) is the theory of the strong interactions. QCD is a quantum field theory and its constituents are a set of fermions, the quarks, and gauge bosons, the gluons. Strongly interacting particles, the hadrons, are bound states of quark and gluon fields. As gluons carry no intrinsic quantum numbers beyond color charge, and because color is believed to be permanently confined, most of the quantum numbers of strongly interacting particles are given by the quantum numbers of their constituent quarks and antiquarks. The description of hadronic properties which strongly emphasizes the role of the minimum-quark-content part of the wave function of a hadron is generically called the quark model.

197

quarkmodrpp.dvi  

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

1 1 by C. Amsler (University of Z¨ urich), T. DeGrand (University of Colorado, Boulder), and B. Krusche (University of Basel). 14.1. Quantum numbers of the quarks Quantum chromodynamics (QCD) is the theory of the strong interactions. QCD is a quantum field theory and its constituents are a set of fermions, the quarks, and gauge bosons, the gluons. Strongly interacting particles, the hadrons, are bound states of quark and gluon fields. As gluons carry no intrinsic quantum numbers beyond color charge, and because color is believed to be permanently confined, most of the quantum numbers of strongly interacting particles are given by the quantum numbers of their constituent quarks and antiquarks. The description of hadronic properties which strongly emphasizes the role of the minimum-quark-content part of the wave function of a hadron is generically called the quark model. It exists

198

Probing QCD with jets, photons and weak bosons at the LHC with ATLAS  

SciTech Connect (OSTI)

A summary of ATLAS measurements that probe 'hard' QCD interactions in the protonproton collisions of the LHC are presented.

Cooper, Ben [University College London, London (United Kingdom); Collaboration: ATLAS Collaboration

2012-10-23T23:59:59.000Z

199

Classical versus quantum coherence  

Science Journals Connector (OSTI)

...M. Stoneham Classical versus quantum coherence P. T. Greenland Department of Physics...nanostructures| Classical versus quantum coherence. | Quantum dots are structures engineered...2002.1134 Classical versus quantum coherence By P. T. Greenland Department of Physics...

2003-01-01T23:59:59.000Z

200

Mesons, PANDA and the scalar glueball  

E-Print Network [OSTI]

The non-perturbative nature of Quantum Chromodynamics (QCD) at low energies has prompted the expectation that the gauge-bosons of QCD -- gluons -- might give rise to compound objects denoted as glueballs. Experimental signals for glueballs have represented a matter of research for various collaborations in the last decades; future research in this direction is a main endeavour planned by the PANDA Collaboration at FAIR. Hence in this article I review some of the outstanding issues in the glueball search, particularly with regard to the ground state -- the scalar glueball, and discuss the relevance for PANDA at FAIR.

Denis Parganlija

2013-12-10T23:59:59.000Z

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.


201

New weakly coupled forces hidden in low-energy QCD  

Science Journals Connector (OSTI)

Is it possible to detect a new weakly coupled force at the QCD scale that interacts primarily with quarks? This work investigates experimental signatures of a new MeV–GeV gauge boson that couples to the baryon number, with attention to the 100 MeV–GeV mass range that is the regime of nonperturbative QCD. Such a state can be searched for in rare radiative decays of light mesons (?,??,?,?) as a ?0? resonance, which is its leading decay mode from 140 to 620 MeV. This is a new discovery window for forces beyond the Standard Model that is not covered by existing dark photon searches.

Sean Tulin

2014-06-05T23:59:59.000Z

202

Strings and supersymmetry as tools for perturbative QCD  

SciTech Connect (OSTI)

We review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. We explain how a supersymmetry-inspired organization works well in conjunction with other tools, namely the color and helicity decompositions of amplitudes, and the constraints imposed by perturbative unitarity and collinear singularities. String theory seems most useful as a heuristic guide. Using these techniques, the complete set of one-loop five-parton QCD amplitudes, as well as certain sequences of special helicity amplitudes with an arbitrary number of external gluons, have been obtained.

Dixon, L.

1995-07-01T23:59:59.000Z

203

Calculation of hadronic matrix elements using lattice QCD  

SciTech Connect (OSTI)

The author gives a brief introduction to the scope of lattice QCD calculations in his effort to extract the fundamental parameters of the standard model. This goal is illustrated by two examples. First the author discusses the extraction of CKM matrix elements from measurements of form factors for semileptonic decays of heavy-light pseudoscalar mesons such as D {yields} Ke{nu}. Second, he presents the status of results for the kaon B parameter relevant to CP violation. He concludes the talk with a short outline of his experiences with optimizing QCD codes on the CM5.

Gupta, R.

1993-08-01T23:59:59.000Z

204

Bulk viscosity of QCD matter near the critical temperature  

E-Print Network [OSTI]

Kubo's formula relates bulk viscosity to the retarded Green's function of the trace of the energy-momentum tensor. Using low energy theorems of QCD for the latter we derive the formula which relates the bulk viscosity to the energy density and pressure of hot matter. We then employ the available lattice QCD data to extract the bulk viscosity as a function of temperature. We find that close to the deconfinement temperature bulk viscosity becomes large, with viscosity-to-entropy ratio zeta/s about 1.

D. Kharzeev; K. Tuchin

2007-05-29T23:59:59.000Z

205

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

206

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

207

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

208

Sum Rules and Cutoff Effects in Wilson Lattice QCD  

E-Print Network [OSTI]

We use the transfer matrix formalism to derive non-perturbative sum rules in Wilson's lattice QCD with N_f flavours of quarks. The discretization errors on these identities are treated in detail. As an application, it is shown how the sum rules can be exploited to give improved estimates of the continuum spectrum and static potential.

Harvey B. Meyer

2006-09-06T23:59:59.000Z

209

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

210

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

211

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

212

Decays of intermediate vector bosons, radiative corrections and QCD jets  

Science Journals Connector (OSTI)

We investigate decay properties of the intermediate vector bosons W± and Z0. QED and QCD radiative corrections to leptonic and hadronic decay modes are calculated. Implications of the results for decay widths, branching ratios, determination of the number of neutrino species, e-?-? universality and properties of hadronic jets produced in W± and Z0 decays are examined.

David Albert; William J. Marciano; Daniel Wyler; Zohreh Parsa

1980-01-01T23:59:59.000Z

213

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

214

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

215

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

216

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

217

Physics as Quantum Information Processing: Quantum Fields as Quantum Automata  

E-Print Network [OSTI]

Can we reduce Quantum Field Theory (QFT) to a quantum computation? Can physics be simulated by a quantum computer? Do we believe that a quantum field is ultimately made of a numerable set of quantum systems that are unitarily interacting? A positive answer to these questions corresponds to substituting QFT with a theory of quantum cellular automata (QCA), and the present work is examining this hypothesis. These investigations are part of a large research program on a "quantum-digitalization" of physics, with Quantum Theory as a special theory of information, and Physics as emergent from the same quantum-information processing. A QCA-based QFT has tremendous potential advantages compared to QFT, being quantum "ab-initio" and free from the problems plaguing QFT due to the continuum hypothesis. Here I will show how dynamics emerges from the quantum processing, how the QCA can reproduce the Dirac-field phenomenology at large scales, and the kind of departures from QFT that that should be expected at a Planck-scale discreteness. I will introduce the notions of linear field quantum automaton and local-matrix quantum automaton, in terms of which I will provide the solution to the Feynman's problem about the possibility of simulating a Fermi field with a quantum computer.

Giacomo Mauro D'Ariano

2011-10-31T23:59:59.000Z

218

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 investigate the relative entropic measure of coherence. Based on its analytical expression, we give an operational interpretation of it with respect to the concept of quantum channel. On this basis, we derive the relation about the coherence and the coherent information in any quantum state. From the point of view of quantum measurement, we furthermore give three trade-offs among the coherence, discord-like and deficit-like quantum correlation quantities for any bipartite quantum state. As an application, we discuss the coherent property of the amplitude damping channel.

Zhengjun Xi; Yongming Li; Heng Fan

2014-08-14T23:59:59.000Z

219

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

220

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

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

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

222

 

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

Döring Döring Bonn University, Bonn, Germany. Resonances: Deciphering the signature of QCD Quantum Chromodynamics (QCD) is the theory of the strong interaction, the fundamental force of nature responsible for the microscopic properties of matter. QCD has left us a signature in form of a rich resonance spectrum, in an energy region where the theory becomes genuinely non-perturbative ---a unique feature that attracts great theoretical interest. QCD manifests itself in these excited states through a complex phenomenology that is currently under intense experimental investigation at JLab and other facilities around the world. From the theory side, non-perturbative approaches have been developed in terms of quarks and gluons, but also relying on hadrons as the relevant degrees of freedom. To connect such

223

Terahertz quantum cascade lasers  

Science Journals Connector (OSTI)

...Michael Pepper Terahertz quantum cascade lasers Jerome Faist 1 Lassaad Ajili...developments in terahertz quantum cascade lasers are reviewed. Structures...magnetic confinement| Terahertz quantum cascade lasers. | Recent developments in...

2004-01-01T23:59:59.000Z

224

Optical quantum memory  

E-Print Network [OSTI]

Quantum memory is important to quantum information processing in many ways: a synchronization device to match various processes within a quantum computer, an identity quantum gate that leaves any state unchanged, and a tool to convert heralded photons to photons-on-demand. In addition to quantum computing, quantum memory would be instrumental for the implementation of long-distance quantum communication using quantum repeaters. The importance of this basic quantum gate is exemplified by the multitude of optical quantum memory mechanisms being studied: optical delay lines, cavities, electromagnetically-induced transparency, photon-echo, and off-resonant Faraday interaction. Here we report on the state-of-the-art in the field of optical quantum memory, including criteria for successful quantum memory and current performance levels.

A. I. Lvovsky; B. C. Sanders; W. Tittel

2010-02-24T23:59:59.000Z

225

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

226

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

227

Understanding localisation in QCD through an Ising-Anderson model  

E-Print Network [OSTI]

Above the QCD chiral crossover temperature, the low-lying eigenmodes of the Dirac operator are localised, while moving up in the spectrum states become extended. This localisation/delocalisation transition has been shown to be a genuine second-order phase transition, in the same universality class as that of the 3D Anderson model. The existence of localised modes and the effective dimensional reduction can be tentatively explained as a consequence of local fluctuations of the Polyakov loop, that provide 3D on-site disorder, in analogy to the on-site disorder of the Anderson model. To test the viability of this explanation we study a 3D effective, Anderson-like model, with on-site disorder provided by the spins of a spin model, which mimics the Polyakov loop dynamics. Our preliminary results show that localised modes are present in the ordered phase, thus supporting the proposed mechanism for localisation in QCD.

Giordano, Matteo; Pittler, Ferenc

2014-01-01T23:59:59.000Z

228

Radiative leptonic decays of B mesons in QCD  

Science Journals Connector (OSTI)

We compute the form factors parametrizing radiative leptonic decays of heavy mesons B+??e+? for photon energies much larger than ?QCD, where perturbative QCD methods for exclusive processes can be combined with the heavy quark effective theory. The form factors can be reliably obtained in this region in an expansion in powers of ?/E?. The leading term in this expansion displays an additional spin symmetry manifested in the equality of form factors of vector and axial vector currents. The leading twist form factors can be written as the convolution of the B meson light-cone wave function with a hard scattering amplitude, which is explicitly calculated to one-loop order. The Sudakov double logarithms of the form [(?s/?)log2(2E?/?)]n are resummed to all orders. As an application we present a method for determining the CKM matrix element |Vub| from a comparison of photon spectra in B and D radiative leptonic decays.

Gregory P. Korchemsky; Dan Pirjol; Tung-Mow Yan

2000-05-10T23:59:59.000Z

229

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)

230

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

231

Hydrodynamic detonation instability in electroweak and QCD phase transitions  

Science Journals Connector (OSTI)

The hydrodynamic stability of deflagration and detonation bubbles for a first order electroweak and QCD phase transition has been discussed recently with the suggestion that detonations are stable. We examine here the case of a detonation more carefully. We find that in front of the bubble wall perturbations do not grow with time, but behind the wall modes exist which grow exponentially. We briefly discuss the possible meaning of this instability.

Mark Abney

1994-02-15T23:59:59.000Z

232

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

233

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

234

QCD and Top Quark Physics at the LHC  

E-Print Network [OSTI]

The expected performance of the ATLAS and CMS detectors at the Large Hadron Collider (LHC) in QCD and top quark measurements is discussed, with a focus on the early data taking phase. Such processes are amongst the primary backgrounds in the searches for new physics, and thus must be understood very well before discoveries can be made. In addition, they serve as useful detector calibration candles.

Frank-Peter Schilling

2009-01-30T23:59:59.000Z

235

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

236

Nuclear Science at NERSC  

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

Accelerator Science Accelerator Science Astrophysics Biological Sciences Chemistry & Materials Science Climate & Earth Science Energy Science Engineering Science Environmental Science Fusion Science Math & Computer Science Nuclear Science Science Highlights NERSC Citations HPC Requirements Reviews Home » Science at NERSC » Nuclear Science Nuclear Science Experimental and theoretical nuclear research carried out at NERSC is driven by the quest for improving our understanding of the building blocks of matter. This includes discovering the origins of nuclei and identifying the forces that transform matter. Specific topics include: Nuclear astrophysics and the synthesis of nuclei in stars and elsewhere in the cosmos; Nuclear forces and quantum chromodynamics (QCD), the quantum field

237

Determination of QCD Backgrounds in ATLAS: A challenge for SUSY searches  

E-Print Network [OSTI]

In this paper we briefly discuss the estimation of uncertainties in QCD backgrounds to searches for Supersymmetry under development by the ATLAS collaboration.

B. Meirose

2009-09-24T23:59:59.000Z

238

Simulating quantum systems on a quantum computer  

Science Journals Connector (OSTI)

...A-eigenstates in the original system state. Also after each observation...1998) Simulating quantum systems on a quantum computer 321 system will be in an eigenstate of...the energy eigenstates. An analysis shows that the relative accuracy...

1998-01-01T23:59:59.000Z

239

Quantum Cybernetics and Complex Quantum Systems Science - A Quantum Connectionist Exploration  

E-Print Network [OSTI]

Quantum cybernetics and its connections to complex quantum systems science is addressed from the perspective of complex quantum computing systems. In this way, the notion of an autonomous quantum computing system is introduced in regards to quantum artificial intelligence, and applied to quantum artificial neural networks, considered as autonomous quantum computing systems, which leads to a quantum connectionist framework within quantum cybernetics for complex quantum computing systems. Several examples of quantum feedforward neural networks are addressed in regards to Boolean functions' computation, multilayer quantum computation dynamics, entanglement and quantum complementarity. The examples provide a framework for a reflection on the role of quantum artificial neural networks as a general framework for addressing complex quantum systems that perform network-based quantum computation, possible consequences are drawn regarding quantum technologies, as well as fundamental research in complex quantum systems science and quantum biology.

Carlos Pedro Gonçalves

2014-02-05T23:59:59.000Z

240

Quantum implicit computational complexity  

Science Journals Connector (OSTI)

We introduce a quantum lambda calculus inspired by Lafont's Soft Linear Logic and capturing the polynomial quantum complexity classes EQP, BQP and ZQP. The calculus is based on the ''classical control and quantum data'' paradigm. This is the first example ... Keywords: Implicit computational complexity, Lambda calculus, Quantum computation

Ugo Dal Lago; Andrea Masini; Margherita Zorzi

2010-01-01T23:59:59.000Z

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.


241

Quantum Dating Market  

E-Print Network [OSTI]

We consider the dating market decision problem under the quantum mechanics point of view. Quantum states whose associated amplitudes are modified by men strategies are used to represent women. Grover quantum search algorithm is used as a playing strategy. Success is more frequently obtained by playing quantum than playing classic.

O. G. Zabaleta; C. M. Arizmendi

2010-03-04T23:59:59.000Z

242

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

243

LANL | Physics | Quantum Information  

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

Breakthrough quantum information Breakthrough quantum information science and technology Physics Division's quantum information science and technology capability supports present and future Laboratory missions in cyber-security, sensing, nonproliferation, information science, and materials. Collaborating with researchers throughout Los Alamos and leading institutions in the nation, Physics Division scientists are involved in projects in quantum communications, including quantum key distribution and quantum-enabled security and networking, and in quantum cold-atom physics. Recent fundamental science results include the ability to "paint" potentials that can trap Bose-Einstein condensates into geometric forms, such as the toroidal ring of clusters, the density of which is measured in

244

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

245

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

246

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

2014-09-04T23:59:59.000Z

247

Integrable Quantum Computation  

E-Print Network [OSTI]

Integrable quantum computation is defined as quantum computing via the integrable condition, in which two-qubit gates are either nontrivial unitary solutions of the Yang--Baxter equation or the Swap gate (permutation). To make the definition clear, in this article, we explore the physics underlying the quantum circuit model, and then present a unified description on both quantum computing via the Bethe ansatz and quantum computing via the Yang--Baxter equation.

Yong Zhang

2011-11-16T23:59:59.000Z

248

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

249

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

250

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

251

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

252

Transverse Momentum-Dependent Parton Distributions From Lattice QCD  

SciTech Connect (OSTI)

Starting from a definition of transverse momentum-dependent parton distributions for semi-inclusive deep inelastic scattering and the Drell-Yan process, given in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection, a scheme to determine such observables in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are presented, focusing in particular on their dependence on the staple extent and the Collins-Soper evolution parameter.

Michael Engelhardt, Bernhard Musch, Philipp Haegler, Andreas Schaefer

2012-12-01T23:59:59.000Z

253

The sigma term and the quark number operator in QCD  

E-Print Network [OSTI]

We discuss the relationship of the forward matrix element of the operator $\\bar\\psi\\psi$, related to the so-called sigma term, to the quark number. We show that in the naive quark model in the canonical formalism these quantities coincide in the limit of small average quark momenta. In the QCD parton model defined through light-front quantization this result is preserved at leading perturbative order but it receives radiative corrections. We analyze the theoretical and phenomenological consequences of this result, which provides a bridge between a current algebra quantity, the sigma term, and a deep-inelastic quantity, the parton number.

Mauro Anselmino; Stefano Forte

1993-05-03T23:59:59.000Z

254

NLO QCD CORRECTIONS TO HADRONIC HIGGS PRODUCTION WITH HEAVY QUARKS.  

SciTech Connect (OSTI)

The production of a Higgs boson in association with a pair of t{bar t} or b{bar b} quarks plays a very important role at both the Tevatron and the Large Hadron Collider. The theoretical prediction of the corresponding cross sections has been improved by including the complete next-to-leading order QCD corrections. After a brief description of the most relevant technical aspects of the calculation, we review the results obtained for both the Tevatron and the Large Hadron Collider.

DAWSON,S.; JACKSON,C.; ORR,L.; REINA,L.; WACHEROTH,D.

2003-07-02T23:59:59.000Z

255

Simultaneous QCD analysis of diffractive and inclusive DIS data  

E-Print Network [OSTI]

We present a novel analysis of diffractive DIS data, in which the input parton distributions of the Pomeron are parameterised using perturbative QCD expressions. In addition to the usual two-gluon model for the perturbative Pomeron, we allow for the possibility that it may be made from two sea quarks. In particular, we treat individually the components of the Pomeron of different size. This property allows the absorptive corrections to the inclusive DIS structure function F_2 to be calculated using the AGK cutting rules. The absorptive effects are found to enhance the size of the gluon distribution of the proton at small x.

Watt, G; Ryskin, M G

2005-01-01T23:59:59.000Z

256

Simultaneous QCD analysis of diffractive and inclusive DIS data  

E-Print Network [OSTI]

We perform a NLO QCD analysis of deep-inelastic scattering data, in which we account for absorptive corrections. These corrections are determined from a simultaneous analysis of diffractive deep-inelastic data. The absorptive effects are found to enhance the size of the gluon distribution at small x, such that a negative input gluon distribution at Q^2 = 1 GeV^2 is no longer required. We discuss the problem that the gluon distribution is valence-like at low scales, whereas the sea quark distribution grows with decreasing x. Our study hints at the possible importance of power corrections for Q^2 \\simeq 1--2 GeV^2.

Martin, A D; Watt, G

2004-01-01T23:59:59.000Z

257

Simultaneous QCD analysis of diffractive and inclusive DIS data  

E-Print Network [OSTI]

We present a novel analysis of diffractive DIS data, in which the input parton distributions of the Pomeron are parameterised using perturbative QCD expressions. In addition to the usual two-gluon model for the perturbative Pomeron, we allow for the possibility that it may be made from two sea quarks. In particular, we treat individually the components of the Pomeron of different size. This property allows the absorptive corrections to the inclusive DIS structure function F_2 to be calculated using the AGK cutting rules. The absorptive effects are found to enhance the size of the gluon distribution of the proton at small x.

G. Watt; A. D. Martin; M. G. Ryskin

2004-12-15T23:59:59.000Z

258

A QCD analysis of diffractive deep-inelastic scattering data  

E-Print Network [OSTI]

We perform a novel type of analysis of diffractive deep-inelastic scattering data, in which the input parton distributions of the Pomeron are parameterised using the perturbative QCD expressions. In particular, we treat individually the components of the Pomeron of different size. We are able to describe simultaneously both the recent ZEUS and H1 diffractive data. In addition to the usual two-gluon model for the perturbative Pomeron, we allow for the possibility that it may be made from two sea quarks.

Martin, A D; Watt, G

2004-01-01T23:59:59.000Z

259

ZZ production at hadron colliders in NNLO QCD  

E-Print Network [OSTI]

We report on the first calculation of next-to-next-to-leading order (NNLO) QCD corrections to the inclusive production of ZZ pairs at hadron colliders. Numerical results are presented for pp collisions with centre-of-mass energy ($\\sqrt{s}$) ranging from 7 to 14 TeV. The NNLO corrections increase the NLO result by an amount varying from $11\\%$ to $17\\%$ as $\\sqrt{s}$ goes from 7 to 14 TeV. The loop-induced gluon fusion contribution provides about $60\\%$ of the total NNLO effect. When going from NLO to NNLO the scale uncertainties do not decrease and remain at the $\\pm 3\\%$ level.

F. Cascioli; T. Gehrmann; M. Grazzini; S. Kallweit; P. Maierhöfer; A. von Manteuffel; S. Pozzorini; D. Rathlev; L. Tancredi; E. Weihs

2014-05-09T23:59:59.000Z

260

ZZ production at hadron colliders in NNLO QCD  

E-Print Network [OSTI]

We report on the first calculation of next-to-next-to-leading order (NNLO) QCD corrections to the inclusive production of ZZ pairs at hadron colliders. Numerical results are presented for pp collisions with centre-of-mass energy ($\\sqrt{s}$) ranging from 7 to 14 TeV. The NNLO corrections increase the NLO result by an amount varying from $11\\%$ to $17\\%$ as $\\sqrt{s}$ goes from 7 to 14 TeV. The loop-induced gluon fusion contribution provides about $60\\%$ of the total NNLO effect. When going from NLO to NNLO the scale uncertainties do not decrease and remain at the $\\pm 3\\%$ level.

Cascioli, F; Grazzini, M; Kallweit, S; Maierhöfer, P; von Manteuffel, A; Pozzorini, S; Rathlev, D; Tancredi, L; Weihs, E

2014-01-01T23:59:59.000Z

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.


261

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

262

Nucleon electromagnetic form factors in twisted mass lattice QCD  

SciTech Connect (OSTI)

We present results on the nucleon electromagnetic form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length L=2.1 fm and L=2.8 fm. Cutoff effects are investigated using three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm. The nucleon magnetic moment, Dirac and Pauli radii are obtained in the continuum limit and chirally extrapolated to the physical pion mass allowing for a comparison with experiment.

Alexandrou, C. [Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Computation-based Science and Technology Research Center, Cyprus Institute, 20 Kavafi Str., Nicosia 2121 (Cyprus); Brinet, M.; Carbonell, J.; Harraud, P. A.; Papinutto, M. [Laboratoire de Physique Subatomique et Cosmologie, UJF/CNRS/IN2P3, 53 avenue des Martyrs, 38026 Grenoble (France); Guichon, P. [CEA-Saclay, IRFU/Service de Physique Nucleaire, 91191 Gif-sur-Yvette (France); Jansen, K. [NIC, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Korzec, T. [Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Institut fuer Physik Humboldt Universitaet zu Berlin, Newtonstrasse 15, 12489 Berlin (Germany); Constantinou, M.

2011-05-01T23:59:59.000Z

263

Meson masses and decay constants from unquenched lattice QCD  

SciTech Connect (OSTI)

We report results for the masses of the flavor nonsinglet light 0{sup ++}, 1{sup --}, and 1{sup +-} mesons from unquenched lattice QCD at two lattice spacings. The twisted mass formalism was used with two flavors of sea quarks. For the 0{sup ++} and 1{sup +-} mesons we look for the effect of decays on the mass dependence. For the light vector mesons we study the chiral extrapolations of the mass. We report results for the leptonic and transverse decay constants of the {rho} meson. We test the mass dependence of the KSRF relations, between the mass, leptonic coupling constant, and strong coupling of the rho meson.

Jansen, K. [DESY, Zeuthen, Platanenallee 6, D-15738 Zeuthen (Germany); McNeile, C. [Department of Physics and Astronomy, Kelvin Building, University of Glasgow, Glasgow, G12 8QQ (United Kingdom); Michael, C. [Theoretical Physics Division, Department of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX (United Kingdom); Urbach, C. [Humboldt-Universitaet zu Berlin, Institut fuer Physik Mathematisch-Naturwissenschaftliche Fakultaet I, Theorie der Elementarteilchen/Phaenomenologie, Newtonstrasse 15, 12489 Berlin (Germany)

2009-09-01T23:59:59.000Z

264

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

265

The Jacobi polynomials QCD analysis for proton spin structure  

SciTech Connect (OSTI)

We present the results of our QCD analysis for polarized quark distribution and structure function xg1(x,Q2). Polarized parton distributions and structure functions of the nucleon are analyzed in the improved valon model. The Polarized valon distribution in a proton and the polarized parton distributions inside the valon are necessary to obtain the polarized parton distributions in a proton. Jacobi polynomial method is used to extract the unknown parameters of the polarized valon distributions by fitting to the available experimental data. The predictions for the NLO calculations of the polarized parton distribution functions are in good agreement with other theoretical models.

Khorramian, Ali N. [Physics Department, Semnan University, Semnan (Iran, Islamic Republic of); Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of); Tehrani, S. Atashbar [Physics Department, Persian Gulf University 75168, Boushehr (Iran, Islamic Republic of); Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of)

2007-06-13T23:59:59.000Z

266

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

267

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

268

Chiral Baryon Fields in the QCD Sum Rule  

E-Print Network [OSTI]

We study the structure of local baryon fields using the method of QCD sum rule. We only consider the single baryon fields and calculate their operator product expansions. We find that the octet baryon fields belonging to the chiral representations [(3,3*)+(3*,3)] and [(8,1)+(1,8)] and the decuplet baryon fields belonging to the chiral representations [(3,6)+(6,3)] lead to the baryon masses which are consistent with the experimental data of ground baryon masses. We also calculate their decay constants, check our normalizations for baryon fields in PRD81:054002(2010) and find that they are well-defined.

Hua-Xing Chen

2012-03-15T23:59:59.000Z

269

QCD corrections to Higgs-boson decay and jet analysis  

Science Journals Connector (OSTI)

We have calculated, within the framework of an on-shell renormalization scheme, the first-order QCD corrections to the rate of Higgs-boson decay to heavy quarks. Our analytic results are in complete agreement with those of Braaten and Leveille. We have also considered the Sterman-Weinberg jet structure for two- and three-jet decays of the Higgs boson. Here our results differ somewhat from those of Braaten and Leveille so we discuss the origin of this discrepancy; we extend their work by keeping the quark mass in the jet formulation.

Pat Kalyniak; Nita Sinha; Rahul Sinha; John N. Ng

1991-06-01T23:59:59.000Z

270

Gaussian quantum information  

Science Journals Connector (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 teleportation are among the most celebrated ideas that have emerged from this new field. It was realized later on that using continuous-variable quantum information carriers, instead of qubits, constitutes an extremely powerful alternative approach to quantum information processing. This review focuses on continuous-variable quantum information processes that rely on any combination of Gaussian states, Gaussian operations, and Gaussian measurements. Interestingly, such a restriction to the Gaussian realm comes with various benefits, since on the theoretical side, simple analytical tools are available and, on the experimental side, optical components effecting Gaussian processes are readily available in the laboratory. Yet, Gaussian quantum information processing opens the way to a wide variety of tasks and applications, including quantum communication, quantum cryptography, quantum computation, quantum teleportation, and quantum state and channel discrimination. This review reports on the state of the art in this field, ranging from the basic theoretical tools and landmark experimental realizations to the most recent successful developments.

Christian Weedbrook; Stefano Pirandola; Raúl García-Patrón; Nicolas J. Cerf; Timothy C. Ralph; Jeffrey H. Shapiro; Seth Lloyd

2012-05-01T23:59:59.000Z

271

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

272

Quantum Information Causality  

Science Journals Connector (OSTI)

How much information can a transmitted physical system fundamentally communicate? We introduce the principle of quantum information causality, which states the maximum amount of quantum information that a quantum system can communicate as a function of its dimension, independently of any previously shared quantum physical resources. We present a new quantum information task, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs.

Damián Pitalúa-García

2013-05-22T23:59:59.000Z

273

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

274

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

275

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

276

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

277

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

278

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

279

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

280

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

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281

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

282

Efficient distributed quantum computing  

Science Journals Connector (OSTI)

...model of a distributed quantum computer. As a result, the circuit...algorithms and the way that quantum computers are likely to be implemented...W.H. was funded by NSF grant nos 0916400, 0829937, 0803478...Large scale modular quantum computer architecture with atomic memory...

2013-01-01T23:59:59.000Z

283

Topological Quantum Distillation  

E-Print Network [OSTI]

We construct a class of topological quantum codes to perform quantum entanglement distillation. These codes implement the whole Clifford group of unitary operations in a fully topological manner and without selective addressing of qubits. This allows us to extend their application also to quantum teleportation, dense coding and computation with magic states.

H. Bombin; M. A. Martin-Delgado

2006-05-16T23:59:59.000Z

284

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

285

Eavesdropping without quantum memory  

E-Print Network [OSTI]

In quantum cryptography the optimal eavesdropping strategy requires that the eavesdropper uses quantum memories in order to optimize her information. What happens if the eavesdropper has no quantum memory? It is shown that the best strategy is actually to adopt the simple intercept/resend strategy.

H. Bechmann-Pasquinucci

2005-04-01T23:59:59.000Z

286

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

287

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

288

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

289

Electron Ion Collider: The Next QCD Frontier Understanding  

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

Electron Electron Ion Collider: The Next QCD Frontier Understanding the glue that binds us all White Paper Writing Committee Elke C. Aschenauer Brookhaven National Laboratory William Brooks Universidad T´ ecnica Federico Santa Maria Abhay Deshpande 1 Stony Brook University Markus Diehl Deutsches Elektronen-Synchrotron DESY Haiyan Gao Duke University Roy Holt Argonne National Laboratory Tanja Horn The Catholic University of America Andrew Hutton Thomas Jefferson National Accelerator Facility Yuri Kovchegov The Ohio State University Krishna Kumar University of Massachusetts, Amherst Zein-Eddine Meziani 1 Temple University Alfred Mueller Columbia University Jianwei Qiu 1 Brookhaven National Laboratory Michael Ramsey-Musolf University of Wisconsin Thomas Roser Brookhaven National Laboratory 1 Co-Editor 1 Franck Sabati´ e Commissariat ` a l' ´ Energie Atomique-Saclay

290

Bulk viscosity of anisotropically expanding hot QCD plasma  

SciTech Connect (OSTI)

The bulk viscosity, {zeta} and its ratio with the shear viscosity, {zeta}/{eta} have been studied in an anisotropically expanding pure glue plasma in the presence of turbulent color fields. It has been shown that the anisotropy in the momentum distribution function of gluons, which has been determined from a linearized transport equation eventually leads to the bulk viscosity. For the isotropic (equilibrium) state, a recently proposed quasiparticle model of pure SU(3) lattice QCD equation of state has been employed where the interactions are encoded in the effective fugacity. It has been argued that the interactions present in the equation of state, significantly contribute to the bulk viscosity. Its ratio with the shear viscosity is significant even at 1.5T{sub c}. Thus, one needs to take in account the effects of the bulk viscosity while studying the hydrodynamic expansion of quark-gluon plasma in the Relativistic Heavy Ion Collider and the Large Hadron Collider.

Chandra, Vinod [Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400005 (India)

2011-11-01T23:59:59.000Z

291

QCD Viscosity to Entropy Density Ratio in the Hadronic Phase  

E-Print Network [OSTI]

Shear viscosity (eta) of QCD in the hadronic phase is computed by the coupled Boltzmann equations of pions and nucleons in low temperatures and low baryon number densities. The eta to entropy density ratio eta/s maps out the nuclear gas-liquid phase transition by forming a valley tracing the phase transition line in the temperature-chemical potential plane. When the phase transition turns into a crossover, the eta/s valley gradually disappears. We suspect the general feature for a first-order phase transition is that eta/s has a discontinuity in the bottom of the eta/s valley. The discontinuity coincides with the phase transition line and ends at the critical point. Beyond the critical point, a smooth eta/s valley is seen. However, the valley could disappear further away from the critical point. The eta/s measurements might provide an alternative to identify the critical points.

Jiunn-Wei Chen; Yen-Han Li; Yen-Fu Liu; Eiji Nakano

2007-03-21T23:59:59.000Z

292

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

293

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

294

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

295

Success Stories: Quantum Dots  

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

Quantum Dots Outshine the Competition for Biomedical Assays Quantum Dots Outshine the Competition for Biomedical Assays Quantum Dots (Qdots), nano-scale semiconductor crystals that emit a range of bright colors when excited by a light source such as a laser, are shining brightly these days. The Berkeley Lab developed technology has been licensed by Quantum Dot Corporation and is being used as fluorescence probes for biomedical assays. The technology just won an R & D 100 Award and Quantum Dot Corporation was named by Fortune magazine as one of 2004's "Cool Companies." Science honored the technology as one of the Top 10 Breakthroughs of the Year in 2003, and Nanotechnology Now named Quantum Dots as the Best Nanotech Product in 2003, among other honors. Quantum Dot Corporation (QDC) is a 1998 start-up biotechnology company

296

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

297

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

298

Search for a Signal on QCD Critical Point in Central Nucleus-Nucleus Collisions  

E-Print Network [OSTI]

We discuss that the QCD critical point could appear in central collisions in percolation cluster. We suggest using the nuclear transparency effect and the one of the light nuclear production to identify the critical point.

M. K. Suleymanov; E. U. Khan; K. Ahmed; Mahnaz Q. Haseeb; Farida Tahir; Y. H. Huseynaliyev; M. Ajaz; K. H. Khan; Z. Wazir

2008-04-19T23:59:59.000Z

299

From strange to charmed baryons using two-flavour QCD Jaume Carbonella  

E-Print Network [OSTI]

From strange to charmed baryons using two-flavour QCD Jaume Carbonella , Vincent Drachb , Mauro.drach@desy.de (Vincent Drach), mauro.papinutto@lpsc.in2p3.fr (Mauro Papinutto) The inclusion of the strange sea quark

Boyer, Edmond

300

Summary of activities in the Working Group on QCD Cascades of the HERA Monte Carlo workshop  

E-Print Network [OSTI]

We summarize the activities in working group 10 concerned with QCD cascades, and find that although much work still needs to be done, much progress was made during this workshop in understanding the merits and deficiencies of different programs.

Nick Brook; Leif Lonnblad

1999-08-16T23:59:59.000Z

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301

Summary of activities in the Working Group on QCD Cascades of the HERA Monte Carlo workshop  

E-Print Network [OSTI]

We summarize the activities in working group 10 concerned with QCD cascades, and find that although much work still needs to be done, much progress was made during this workshop in understanding the merits and deficiencies of different programs.

Brook, N; Brook, Nick; Lonnblad, Leif

1999-01-01T23:59:59.000Z

302

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

303

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

304

Inclusive Single- and Dijet Rates in Next-to-Leading Order QCD for ?*p and ?*? Collisions  

Science Journals Connector (OSTI)

We present one- and two-jet inclusive cross sections for ?*? scattering and virtual photoproduction in ep collisions. The hard cross sections are calculated in next-to-leading order QCD. Soft and collinear singul...

B. Pötter

2000-12-01T23:59:59.000Z

305

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

306

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

307

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

308

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.

Quan, H T

2008-01-01T23:59:59.000Z

309

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

310

Ultraviolet-Renormalon Calculus  

Science Journals Connector (OSTI)

We consider the status of the so-called ultraviolet (UV) renormalon which contributes to large order divergences of perturbative expansions in quantum chromodynamics. We argue that although the renormalon is associated with short distance dynamics, the class of renormalon graphs is not well defined and its overall weight is not controlled by theory. From this point of view there is not much difference from the case of Borel nonsummable singularities. Phenomenologically the UV renormalon is related to an effective four-fermion interaction originating within fundamental QCD.

A. I. Vainshtein and V. I. Zakharov

1994-08-29T23:59:59.000Z

311

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

312

The Quantum Field as a Quantum Computer  

E-Print Network [OSTI]

It is supposed that at very small scales a quantum field is an infinite homogeneous quantum computer. On a quantum computer the information cannot propagate faster than $c=a/\\tau$, $a$ and $\\tau$ being the minimum space and time distances between gates, respectively. It is shown that the information flow satisfies a Dirac equation, with speed $v=\\zeta c$ and $\\zeta=\\zeta(m)$ mass-dependent. For $a/\\tau=c$ the speed of light $\\zeta^{-1}$ is a vacuum refraction index increasing monotonically from $\\zeta^{-1}(0)=1$ to $\\zeta^{-1}(M)=\\infty$, $M$ being the Planck mass for $2a$ the Planck length.

Giacomo Mauro D'Ariano

2010-12-02T23:59:59.000Z

313

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

314

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

315

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

316

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

317

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

318

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

319

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

320

Quantum computation of scattering in scalar quantum field theories  

Science Journals Connector (OSTI)

Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational ... Keywords: quantum algorithm, quantum field theory, simulation

Stephen P. Jordan, Keith S. M. Lee, John Preskill

2014-09-01T23:59:59.000Z

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

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

322

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

323

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

324

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

325

Quantum Imaging Technologies  

E-Print Network [OSTI]

Over the past three decades, quantum mechanics has allowed the development of technologies that provide unconditionally secure communication. In parallel, the quantum nature of the transverse electromagnetic field has spawned the field of quantum imaging that encompasses technologies such as quantum ghost imaging and high-dimensional quantum key distribution (QKD). The emergence of such quantum technologies also highlights the need for the development of methods for characterizing the elusive quantum state itself. In this document, we describe new technologies that use the quantum properties of light for security. The first is a technique that extends the principles behind QKD to the field of imaging. By applying the polarization-based BB84 protocol to individual photons in an active imaging system, we obtained images that are secure against intercept-resend jamming attacks. The second technology presented in this article is based on an extension of quantum ghost imaging. We used a holographic filtering technique to build a quantum ghost image identification system that uses a few pairs of photons to identify an object from a set of known objects. The third technology addressed in this document is a high-dimensional QKD system that uses orbital-angular-momentum (OAM) modes of light for encoding. Moving to a high-dimensional state space in QKD allows one to impress more information on each photon, as well as introduce higher levels of security. We discuss the development of two OAM-QKD protocols based on the BB84 and Ekert QKD protocols. The fourth and final technology presented in this article is a relatively new technique called direct measurement that uses sequential weak and strong measurements to characterize a quantum state. We use this technique to characterize the quantum state of a photon with a dimensionality of d=27, and measure its rotation in the natural basis of OAM.

Mehul Malik; Robert W. Boyd

2014-06-06T23:59:59.000Z

326

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

327

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

328

Quantum-assisted biomolecular modelling  

Science Journals Connector (OSTI)

...incremental improvements. Quantum computing offers the possibility...might be addressed using quantum computation and speculate on the future importance of quantum-assisted biomolecular...self-organization and molecular motors are central to all cellular...

2010-01-01T23:59:59.000Z

329

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

330

Instantaneous Quantum Computation  

E-Print Network [OSTI]

We examine theoretic architectures and an abstract model for a restricted class of quantum computation, called here instantaneous quantum computation because it allows for essentially no temporal structure within the quantum dynamics. Using the theory of binary matroids, we argue that the paradigm is rich enough to enable sampling from probability distributions that cannot, classically, be sampled from efficiently and accurately. This paradigm also admits simple interactive proof games that may convince a skeptic of the existence of truly quantum effects. Furthermore, these effects can be created using significantly fewer qubits than are required for running Shor's Algorithm.

Dan Shepherd; Michael J. Bremner

2008-09-04T23:59:59.000Z

331

Efficient Distributed Quantum Computing  

E-Print Network [OSTI]

We provide algorithms for efficiently addressing quantum memory in parallel. These imply that the standard circuit model can be simulated with low overhead by the more realistic model of a distributed quantum computer. As a result, the circuit model can be used by algorithm designers without worrying whether the underlying architecture supports the connectivity of the circuit. In addition, we apply our results to existing memory intensive quantum algorithms. We present a parallel quantum search algorithm and improve the time-space trade-off for the Element Distinctness and Collision problems.

Robert Beals; Stephen Brierley; Oliver Gray; Aram Harrow; Samuel Kutin; Noah Linden; Dan Shepherd; Mark Stather

2012-07-10T23:59:59.000Z

332

Quantum Metropolis Sampling  

E-Print Network [OSTI]

The original motivation to build a quantum computer came from Feynman who envisaged a machine capable of simulating generic quantum mechanical systems, a task that is believed to be intractable for classical computers. Such a machine would have a wide range of applications in the simulation of many-body quantum physics, including condensed matter physics, chemistry, and high energy physics. Part of Feynman's challenge was met by Lloyd who showed how to approximately decompose the time-evolution operator of interacting quantum particles into a short sequence of elementary gates, suitable for operation on a quantum computer. However, this left open the problem of how to simulate the equilibrium and static properties of quantum systems. This requires the preparation of ground and Gibbs states on a quantum computer. For classical systems, this problem is solved by the ubiquitous Metropolis algorithm, a method that basically acquired a monopoly for the simulation of interacting particles. Here, we demonstrate how to implement a quantum version of the Metropolis algorithm on a quantum computer. This algorithm permits to sample directly from the eigenstates of the Hamiltonian and thus evades the sign problem present in classical simulations. A small scale implementation of this algorithm can already be achieved with today's technology

K. Temme; T. J. Osborne; K. G. Vollbrecht; D. Poulin; F. Verstraete

2009-11-18T23:59:59.000Z

333

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

334

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

335

Terahertz Quantum Cascade Lasers  

Science Journals Connector (OSTI)

We provide an overview of terahertz quantum cascade lasers based on resonant-phonon depopulation and metal-metal waveguides, including two-phonon resonant-phonon depopulation...

Williams, Benjamin; Kumar, Sushil; Qin, Qi; Lee, Alan Wei Min; Hu, Qing; Reno, John L; Wasilewski, Z R; Liu, H C

336

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

337

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...

338

Quantum Junction Solar Cells  

Science Journals Connector (OSTI)

Quantum Junction Solar Cells ... § Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario, M5S 3G4, Canada ...

Jiang Tang; Huan Liu; David Zhitomirsky; Sjoerd Hoogland; Xihua Wang; Melissa Furukawa; Larissa Levina; Edward H. Sargent

2012-08-10T23:59:59.000Z

339

Quantum random access memory  

E-Print Network [OSTI]

A random access memory (RAM) uses n bits to randomly address N=2^n distinct memory cells. A quantum random access memory (qRAM) uses n qubits to address any quantum superposition of N memory cells. We present an architecture that exponentially reduces the requirements for a memory call: O(log N) switches need be thrown instead of the N used in conventional (classical or quantum) RAM designs. This yields a more robust qRAM algorithm, as it in general requires entanglement among exponentially less gates, and leads to an exponential decrease in the power needed for addressing. A quantum optical implementation is presented.

Vittorio Giovannetti; Seth Lloyd; Lorenzo Maccone

2007-08-14T23:59:59.000Z

340

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

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

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

342

Majorization-preserving quantum channels  

E-Print Network [OSTI]

In this report, we give a characterization to those quantum channels that preserve majorization relationship between quantum states. Some remarks are presented as well.

Lin Zhang

2012-09-24T23:59:59.000Z

343

Sandia National Laboratories: Quantum Systems  

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

Quantum Systems Sensors Sandia leverages quantum mechanics to enable exquisite metrology devices, such as inertial sensors and frequency standards that go beyond the capabilities...

344

The Quantum Side of Photosynthesis  

Science Journals Connector (OSTI)

The Quantum Side of Photosynthesis ... But evidence is mounting that photosynthetic organisms may, in fact, capitalize on quantum effects to harness the sun’s rays. ...

JYLLIAN KEMSLEY

2012-02-19T23:59:59.000Z

345

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

346

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

347

Electric and magnetic response of hot QCD matter  

E-Print Network [OSTI]

We study the electric conductivity as well as the magnetic response of hot QCD matter at various temperatures $T$ and chemical potentials $\\mu_q$ within the off-shell Parton-Hadron-String Dynamics (PHSD) transport approach for interacting partonic systems in a finite box with periodic boundary conditions. The response of the strongly-interacting system in equilibrium to an external electric field defines the electric conductivity $\\sigma_0$ whereas the response to a moderate external magnetic field defines the induced diamagnetic moment $\\mu_L$ ($T, \\mu_q$) as well as the spin susceptibility $\\chi_S(T, \\mu_q)$. We find a sizeable temperature dependence of the dimensionless ratio $\\sigma_0/T$ well in line with calculations in a relaxation time approach for $T_c \\! line with results from the Dynamical QuasiParticle Model (DQPM). The spin susceptibility $\\chi_S(T,\\mu_q)$ is found to increase with temperature $T$ and to rise $\\sim \\mu_q ^2/T^2$, too. The actual values for the magnetic response of the QGP in the temperature range below 250 MeV show that the QGP should respond diamagnetically in actual ultra-relativistic heavy-ion collisions since the maximal magnetic fields created in these collisions are smaller than $B_c(T)$ which defines a boundary between diamagnetism and paramagnetism.

T. Steinert; W. Cassing

2013-12-11T23:59:59.000Z

348

Quantum motor and future  

E-Print Network [OSTI]

In a popular language, the possibilities of the Casimir expulsion effect are presented, which can be the basis of quantum motors. Such motors can be in the form of a special multilayer thin film with periodic and complex nanosized structures. Quantum motors of the type of the Casimir platforms can be the base of transportation, energy and many other systems in the future.

Fateev, Evgeny G

2013-01-01T23:59:59.000Z

349

Quantum motor and future  

E-Print Network [OSTI]

In a popular language, the possibilities of the Casimir expulsion effect are presented, which can be the basis of quantum motors. Such motors can be in the form of a special multilayer thin film with periodic and complex nanosized structures. Quantum motors of the type of the Casimir platforms can be the base of transportation, energy and many other systems in the future.

Evgeny G. Fateev

2013-01-20T23:59:59.000Z

350

Isotope - based Quantum Information  

E-Print Network [OSTI]

This paper is brief review of three aspects of the isotope - based quantum information: computation, teleportation and cryptography. Our results demonstrate not only that entanglement exists in elementary excitation of isotope - mixed solids but also it can be used for quantum information processing.

Vladimir G. Plekhanov

2009-09-04T23:59:59.000Z

351

Reliable quantum computers  

Science Journals Connector (OSTI)

...the performance of a useful quantum computer will need to be. And that in itself...by the Department of Energy under Grant No. DE- FG03-92-ER40701, and...Lond. A (1998) Reliable quantum computers 409 References Aharonov, D. & Ben-Or...

1998-01-01T23:59:59.000Z

352

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

353

Quantum dot cascade laser  

Science Journals Connector (OSTI)

We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode...??~?6.15 ?m and a bro...

Ning Zhuo; Feng Qi Liu; Jin Chuan Zhang; Li Jun Wang…

2014-03-01T23:59:59.000Z

354

Relation of QCD sum rules in matter and the nuclear many-body problem  

Science Journals Connector (OSTI)

The method of QCD sum rules provides a powerful technique for the calculation of properties of hadrons in terms of a number of parameters that specify various condensate matrix elements. One may hope that it will be possible to calculate some of the condensate matrix elements using effective Lagrangians. If we concentrate on quark condensates, the Nambu–Jona-Lasinio model may provide a useful model. In this work we study the relation between relativistic nuclear many-body theory and the analysis of the nucleon self-energy in nuclear matter made using QCD sum rules. This is done by introducing the fields of a bosonized version of the Nambu–Jona-Lasinio (NJL) model. Using the simplest version of the QCD sum-rule analysis, we replace the QCD order parameters in matter with related order parameters describing a Lorentz scalar and a vector field. In our mean-field analysis we find that the many-body theory, based upon the bosonization of the NJL model, is consistent with the simplest version of the QCD sum-rule calculation of the nucleon self-energy in matter.

C. M. Shakin

1994-08-01T23:59:59.000Z

355

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

356

Reasoning about quantum knowledge  

E-Print Network [OSTI]

We construct a formal framework for investigating epistemic and temporal notions in the context of distributed quantum computation. While we rely on structures developed earlier, we stress that our notion of quantum knowledge makes sense more generally in any agent-based model for distributed quantum systems. Several arguments are given to support our view that an agent's possibility relation should not be based on the reduced density matrix, but rather on local classical states and local quantum operations. In this way, we are able to analyse distributed primitives such as superdense coding and teleportation, obtaining interesting conclusions as to how the knowledge of individual agents evolves. We show explicitly that the knowledge transfer in teleportation is essentially classical, in that eventually, the receiving agent knows that its state is equal to the initial state of the sender. The relevant epistemic statements for teleportation deal with this correlation rather than with the actual quantum state, which is unknown throughout the protocol.

Ellie D'Hondt; Prakash Panangaden

2005-07-19T23:59:59.000Z

357

An Invisible Quantum Tripwire  

E-Print Network [OSTI]

We present here a quantum tripwire, which is a quantum optical interrogation technique capable of detecting an intrusion with very low probability of the tripwire being revealed to the intruder. Our scheme combines interaction-free measurement with the quantum Zeno effect in order to interrogate the presence of the intruder without interaction. The tripwire exploits a curious nonlinear behaviour of the quantum Zeno effect we discovered, which occurs in a lossy system. We also employ a statistical hypothesis testing protocol, allowing us to calculate a confidence level of interaction-free measurement after a given number of trials. As a result, our quantum intruder alert system is robust against photon loss and dephasing under realistic atmospheric conditions and its design minimizes the probabilities of false positives and false negatives as well as the probability of becoming visible to the intruder.

Petr M. Anisimov; Daniel J. Lum; S. Blane McCracken; Hwang Lee; Jonathan P. Dowling

2010-02-17T23:59:59.000Z

358

Effective equations for the quantum pendulum from momentous quantum mechanics  

SciTech Connect (OSTI)

In this work we study the quantum pendulum within the framework of momentous quantum mechanics. This description replaces the Schroedinger equation for the quantum evolution of the system with an infinite set of classical equations for expectation values of configuration variables, and quantum dispersions. We solve numerically the effective equations up to the second order, and describe its evolution.

Hernandez, Hector H.; Chacon-Acosta, Guillermo [Universidad Autonoma de Chihuahua, Facultad de Ingenieria, Nuevo Campus Universitario, Chihuahua 31125 (Mexico); Departamento de Matematicas Aplicadas y Sistemas, Universidad Autonoma Metropolitana-Cuajimalpa, Artificios 40, Mexico D. F. 01120 (Mexico)

2012-08-24T23:59:59.000Z

359

Quantum Degrees of Freedom, Quantum Integrability and Entanglment Generators  

E-Print Network [OSTI]

Dynamical algebra notion of quantum degrees of freedom is utilized to study the relation between quantum dynamical integrability and generalized entanglement. It is argued that a quantum dynamical system generates generalized entanglement by internal dynamics if and only if it is quantum non-integrable. Several examples are used to illustrate the relation.

Nikola Buric

2010-03-26T23:59:59.000Z

360

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

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

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

362

Chiral magnetic effect in 2+1 flavor QCD+QED  

E-Print Network [OSTI]

The exciting possibility of direct observation of QCD instantons in heavy-ion collisions has recently been proposed by Kharzeev. The underlying phenomenon, known as the chiral magnetic effect, may have been observed recently at RHIC, and a first principles calculation is needed to confirm and understand the results. The chiral magnetic effect is thought to be visible in the symmetric phase, at temperatures above the QCD critical temperature, and in the presence of an external magnetic field. We report on first 2+1 flavor, domain wall fermion, QCD+QED dynamical simulations above the critical temperature, in a fixed topological sector(s), which are used to study the electric charge separation produced by the effect.

M. Abramczyk; T. Blum; G. Petropoulos; R. Zhou

2009-11-06T23:59:59.000Z

363

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

364

Local coherence and deflation of the low quark modes in lattice QCD  

E-Print Network [OSTI]

The spontaneous breaking of chiral symmetry in QCD is known to be linked to a non-zero density of eigenvalues of the massless Dirac operator near the origin. Numerical studies of two-flavour QCD now suggest that the low quark modes are locally coherent to a certain extent. As a consequence, the modes can be simultaneously deflated, using local projectors, with a total computational effort proportional to the lattice volume (rather than its square). Deflation has potentially many uses in lattice QCD. The technique is here worked out for the case of quark propagator calculations, where large speed-up factors and a flat scaling behaviour with respect to the quark mass are achieved.

Martin Lüscher

2007-06-15T23:59:59.000Z

365

Recursion relations for the general tree-level amplitudes in QCD with massive dirac fields  

E-Print Network [OSTI]

QCD amplitudes with many external fields have been studied for a long time. At tree-level, the amplitudes can be obtained effectively by the BCFW recursion relations. In this article, we extend the Britto-Cachazo-Feng-Witten (BCFW) relations to the QCD amplitude of which the external fields are all massive or include only one massless line. We find such amplitude can be split into two parts and each part of the amplitude is of some correlated spin configuration between the two shifted lines. After choosing proper momentum shift scheme, we can show that each part is constructible directly. Hence, we can obtain a general procedure for the amplitudes in QCD by the BCFW recursion relations. We apply the procedure to several amplitudes as examples. We find such methods are very efficient when there are many massive external fields in the amplitudes.

Gang Chen

2011-03-13T23:59:59.000Z

366

Estimating nonlinear QCD effects in ultrahigh energy neutrino events at IceCube  

Science Journals Connector (OSTI)

The number of ultrahigh energy events at IceCube is estimated, for the first time, taking into account nonlinear QCD effects in the neutrino-hadron cross section. We assume that the extragalactic neutrino flux is given by ??(E?)=?0E??2 and estimate the neutrino-hadron cross section using the dipole approach and a phenomenological model for the dipole-hadron cross section based on nonlinear QCD dynamics. We demonstrate that the nonlinear prediction is able to describe the current IceCube data and that the magnitude of the nonlinear effects is larger than 20% for visible energies of order of 2 PeV and increases with the neutrino energy. Our main conclusion is that the nonlinear QCD effects are non-negligible and should be taken into account in the analysis of the number of ultrahigh energy events.

V.?P. Gonçalves and D.?R. Gratieri

2014-09-11T23:59:59.000Z

367

Nucleon Structure and Hyperon Form Factors from Lattice QCD.  

SciTech Connect (OSTI)

In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point. to be 1.23(5), consistent with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(2G), consistent with the Adelaide-JLab Collaboration's result. The hyperon {Sigma} and {Xi} axial coupling constants are also performed for the first time in a lattice calculation, g{sub {Sigma}{Sigma}} = 0.441(14) and g{sub {Xi}{Xi}} = -0.277(11).

Lin,H.W.

2007-06-11T23:59:59.000Z

368

Quantum Channels with Memory  

E-Print Network [OSTI]

We present a general model for quantum channels with memory, and show that it is sufficiently general to encompass all causal automata: any quantum process in which outputs up to some time t do not depend on inputs at times t' > t can be decomposed into a concatenated memory channel. We then examine and present different physical setups in which channels with memory may be operated for the transfer of (private) classical and quantum information. These include setups in which either the receiver or a malicious third party have control of the initializing memory. We introduce classical and quantum channel capacities for these settings, and give several examples to show that they may or may not coincide. Entropic upper bounds on the various channel capacities are given. For forgetful quantum channels, in which the effect of the initializing memory dies out as time increases, coding theorems are presented to show that these bounds may be saturated. Forgetful quantum channels are shown to be open and dense in the set of quantum memory channels.

Dennis Kretschmann; Reinhard F. Werner

2005-02-17T23:59:59.000Z

369

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

370

Quantum technology: the second quantum revolution  

Science Journals Connector (OSTI)

...be an electron or nuclear spin in a molecule...the Coulomb energy cost of adding one extra...1667 A B A' B' C D BS M M S - 0 2.0 1...resolution at low cost. In addition to writing...A silicon-based nuclear spin quantum computer...

2003-01-01T23:59:59.000Z

371

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

372

Moment Analysis of Hadronic Vacuum Polarization - Proposal for a lattice QCD evaluation of $g_?-2$  

E-Print Network [OSTI]

I suggest a new approach to the determination of the hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon $a_{\\mu}^{\\rm HVP}$ in lattice QCD. It is based on properties of the Mellin transform of the hadronic spectral function and their relation to the HVP self energy in the Euclidean. I show how $a_{\\mu}^{\\rm HVP}$ is very well approximated by a few moments associated to this Mellin transform and how these moments can be evaluated in lattice QCD, providing thus a series of tests when compared with the corresponding determinations using experimental data.

Eduardo de Rafael

2014-06-18T23:59:59.000Z

373

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

374

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

375

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

376

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

377

Hydrodynamic Stability Analysis of Burning Bubbles in Electroweak Theory and in QCD  

E-Print Network [OSTI]

Assuming that the electroweak and QCD phase transitions are first order, upon supercooling, bubbles of the new phase appear. These bubbles grow to macroscopic sizes compared to the natural scales associated with the Compton wavelengths of particle excitations. They propagate by burning the old phase into the new phase at the surface of the bubble. We study the hydrodynamic stability of the burning and find that for the velocities of interest for cosmology in the electroweak phase transition, the shape of the bubble wall is stable under hydrodynamic perturbations. Bubbles formed in the cosmological QCD phase transition are found to be a borderline case between stability and instability.

P. Huet; K. Kajantie; R. G. Leigh; B. -H. Liu; L. McLerran

1992-12-05T23:59:59.000Z

378

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

379

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

380

Stabilizing quantum information  

Science Journals Connector (OSTI)

The dynamical-algebraic structure underlying all the schemes for quantum information stabilization is argued to be fully contained in the reducibility of the operator algebra describing the interaction with the environment of the coding quantum system. This property amounts to the existence of a nontrivial group of symmetries for the global dynamics. We provide a unified framework that allows us to build systematically additional classes of error correcting codes and noiseless subsystems. It is shown that by using symmetrization strategies one can artificially produce noiseless subsystems supporting universal quantum computation.

Paolo Zanardi

2000-12-05T23:59:59.000Z

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

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

382

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

383

Parasupersymmetry in Quantum Graphs  

E-Print Network [OSTI]

We study hidden parasupersymmetry structures in purely bosonic quantum mechanics on compact equilateral graphs. We consider a single free spinless particle on the graphs and show that the Huang-Su parasupersymmetry algebra is hidden behind degenerate spectra.

Satoshi Ohya

2012-10-29T23:59:59.000Z

384

Parasupersymmetry in Quantum Graphs  

E-Print Network [OSTI]

We study hidden parasupersymmetry structures in purely bosonic quantum mechanics on compact equilateral graphs. We consider a single free spinless particle on the graphs and show that the Rubakov-Spiridonov-Khare-Tomiya parasupersymmetries are hidden behind degenerate spectra.

Ohya, Satoshi

2012-01-01T23:59:59.000Z

385

Integrable quantum mappings  

Science Journals Connector (OSTI)

A quantum R-matrix structure is presented for a family of exactly integrable multidimensional rational mappings related to lattice versions of the Korteweg–de Vries equation. It is shown that these mappings possess a commuting family of invariants.

F. W. Nijhoff; H. W. Capel; V. G. Papageorgiou

1992-08-15T23:59:59.000Z

386

Wires with Quantum Memory  

E-Print Network [OSTI]

We show that quantum particles constrained to move along curves undergoing cyclic deformations acquire, in general, geometric phases. We treat explicitly an example, involving particular deformations of a circle, and ponder on potential applications.

C. Chryssomalakos; H. Hernandez; D. Gelbwaser-Klimovsky; E. Okon

2008-04-19T23:59:59.000Z

387

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

388

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

389

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

390

Time in quantum mechanics  

E-Print Network [OSTI]

OF CONTENTS I. INTRODUCTION II. HISTORICAL DEVELOPMENT A. Classical Mechanics B. Quantum Theory . C. The Problem 3 4 6 III. TIME ATOMS AND DISCRETE TIME A. The Earliest Applications of Atomistic and Discrete Time . . . . . B. The Radiating Electron... . C. Quantum Field Theory 8 10 l2 IV. TIME OPERATOR FORMULATIONS 16 A. Advocates Against a Time Operator . B. The Possibility of a Time Operator C, Advocates in Favor of a Time Operator D. A Restricted Time Delay Operator: Scattering Theory...

Chapin, Kimberly R.

2012-06-07T23:59:59.000Z

391

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

392

Quantum robots and environments  

Science Journals Connector (OSTI)

Quantum robots and their interactions with environments of quantum systems are described, and their study justified. A quantum robot is a mobile quantum system that includes an on-board quantum computer and needed ancillary systems. Quantum robots carry out tasks whose goals include specified changes in the state of the environment, or carrying out measurements on the environment. Each task is a sequence of alternating computation and action phases. Computation phase activites include determination of the action to be carried out in the next phase, and recording of information on neighborhood environmental system states. Action phase activities include motion of the quantum robot and changes in the neighborhood environment system states. Models of quantum robots and their interactions with environments are described using discrete space and time. A unitary step operator T that gives the single time step dynamics is associated with each task. T=Ta+Tc is a sum of action phase and computation phase step operators. Conditions that Ta and Tc should satisfy are given along with a description of the evolution as a sum over paths of completed phase input and output states. A simple example of a task—carrying out a measurement on a very simple environment—is analyzed in detail. A decision tree for the task is presented and discussed in terms of the sums over phase paths. It is seen that no definite times or durations are associated with the phase steps in the tree, and that the tree describes the successive phase steps in each path in the sum over phase paths.

Paul Benioff

1998-08-01T23:59:59.000Z

393

Chiral Quantum Walks  

E-Print Network [OSTI]

Wigner separated the possible types of symmetries in quantum theory into those symmetries that are unitary and those that are antiunitary. Unitary symmetries have been well studied whereas antiunitary symmetries and the physical implications associated with time-reversal symmetry breaking have had little influence on quantum information science. Here we develop a quantum circuits version of time-reversal symmetry theory, classifying time-symmetric and time-asymmetric Hamiltonians and circuits in terms of their underlying network elements and geometric structures. These results reveal that many of the typical quantum circuit networks found across the field of quantum information science exhibit time-asymmetry. We then experimentally implement the most fundamental time-reversal asymmetric process, applying local gates in an otherwise time-symmetric circuit to induce time-reversal asymmetry and thereby achieve (i) directional biasing in the transition probability between basis states, (ii) the enhancement of and (iii) the suppression of these transport probabilities. Our results imply that the physical effect of time-symmetry breaking plays an essential role in coherent transport and its control represents an omnipresent yet essentially untapped resource in quantum transport science.

DaWei Lu; Jacob D. Biamonte; Jun Li; Hang Li; Tomi H. Johnson; Ville Bergholm; Mauro Faccin; Zoltán Zimborás; Raymond Laflamme; Jonathan Baugh; Seth Lloyd

2014-05-23T23:59:59.000Z

394

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

395

SciTech Connect: Quark mass variation constraints from Big Bang...  

Office of Scientific and Technical Information (OSTI)

NUCLEAR PHYSICS; NUCLEOSYNTHESIS; QUANTUM CHROMODYNAMICS; QUARKS; REACTION KINETICS Word Cloud More Like This Full Text preview image File size NAView Full Text View Full Text...

396

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

397

Quantum graph as a quantum spectral filter  

SciTech Connect (OSTI)

We study the transmission of a quantum particle along a straight input-output line to which a graph {Gamma} is attached at a point. In the point of contact we impose a singularity represented by a certain properly chosen scale-invariant coupling with a coupling parameter {alpha}. We show that the probability of transmission along the line as a function of the particle energy tends to the indicator function of the energy spectrum of {Gamma} as {alpha}{yields}{infinity}. This effect can be used for a spectral analysis of the given graph {Gamma}. Its applications include a control of a transmission along the line and spectral filtering. The result is illustrated with an example where {Gamma} is a loop exposed to a magnetic field. Two more quantum devices are designed using other special scale-invariant vertex couplings. They can serve as a band-stop filter and as a spectral separator, respectively.

Turek, Ondrej; Cheon, Taksu [Laboratory of Physics, Kochi University of Technology, Tosa Yamada, Kochi 782-8502 (Japan)] [Laboratory of Physics, Kochi University of Technology, Tosa Yamada, Kochi 782-8502 (Japan)

2013-03-15T23:59:59.000Z

398

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

399

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

400

Detection of gravitational waves from the QCD phase transition with pulsar timing arrays  

Science Journals Connector (OSTI)

If the cosmological QCD phase transition is strongly first order and lasts sufficiently long, it generates a background of gravitational waves which may be detected via pulsar timing experiments. We estimate the amplitude and the spectral shape of such a background and we discuss its detectability prospects.

Chiara Caprini; Ruth Durrer; Xavier Siemens

2010-09-08T23:59:59.000Z

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.


401

Gauge-invariant truncation scheme for the Schwinger-Dyson equations of QCD  

Science Journals Connector (OSTI)

We present a new truncation scheme for the Schwinger-Dyson equations of QCD that respects gauge invariance at any level of the dressed loop expansion. When applied to the gluon self-energy, it allows for its nonperturbative treatment without compromising the transversality of the solution, even when entire sets of diagrams (most notably the ghost loops) are omitted or treated perturbatively.

D. Binosi and J. Papavassiliou

2008-03-19T23:59:59.000Z

402

Testing QCD Plasma Formation by Pion Correlations in Relativistic Nuclear Collisions  

Science Journals Connector (OSTI)

To test the formation of a deconfined QCD plasma in relativistic nuclear collisions, we propose measuring the charge anticorrelations of pions of similar momenta. These anticorrelations will be greatly weakened by plasma formation, and their kinematic characteristics will also change in a predicted way.

Jorge A. Lopez; Jitendra C. Parikh; Philip J. Siemens

1984-09-24T23:59:59.000Z

403

Semileptonic decay of B and D?K0*(1430)?¯? from QCD sum rule  

Science Journals Connector (OSTI)

We calculate B(s) and D(s) to K0*(1430) transition form factors, and study semileptonic decays of B(s) and D(s)?K0*(1430)?¯? based on QCD sum rule. Measuring these semileptonic decays with high statistics will give valuable information on the nature of light scalar mesons.

Mao-Zhi Yang

2006-02-23T23:59:59.000Z

404

Photo-production of Positive Parity Excited Baryons in the 1/Nc Expansion of QCD  

E-Print Network [OSTI]

We analyze the photo-production helicity amplitudes for the positive parity excited baryons in the context of the $1/N_c$ expansion of QCD. The results show that sub-leading corrections in $1/N_c$ are important and that, while 1-body effective operators are dominant, there is some evidence for the need of 2-body effects.

Jose L. Goity Norberto N. Scoccola

2007-01-29T23:59:59.000Z

405

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

406

Magnetic moments of $?_Q^\\prime$-$?_Q$ transitions in light cone QCD  

E-Print Network [OSTI]

The $\\Xi_Q^\\prime$-$\\Xi_Q$ transition magnetic moments are calculated in framework of the light cone QCD sum rules method (LCSR). The values of the transition magnetic moments obtained are compared with the predictions of the other theoretical approaches.

T. M. Aliev; K. Azizi; M. Savci

2014-02-21T23:59:59.000Z

407

Handbook of Higher Twist Distribution Amplitudes of Vector Mesons in QCD  

E-Print Network [OSTI]

We give a summary of existing results on higher twist distribution amplitudes of vector mesons in QCD. Special attention is payed to meson mass corrections which turn out to be large. A ``shopping list'' is presented of most important nonperturbative parameters which enter distribution amplitudes.

Patricia Ball; V. M. Braun

1998-08-05T23:59:59.000Z

408

I REMARKS ON THE TOPOLOGY OF GAUGE FIELDS*  

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

! 8 ' SLAC-PUB-2089 March 1978 (T) I REMARKS ON THE TOPOLOGY OF GAUGE FIELDS* t Y. Nambu Stanford Linear Accelerator Center Stanford University, Stanford, California 94305 In contrast to the short distance behavior of quantum chromodynamics (QCD), which is within the scope of perturbation theory and thus can be subjected to quantitative t e s t s , the large distance or strong coupling regime of QCD is not well understood yet even qualitatively. An overriding problem of interest in quark confinement, and various theoretical schemes have been put forward to show that the quarks can indeed be confined. These schemes, though , varying from one to another i n detail, rely on the idea that the growing coupling constant at large distances plays a key role. It is not clear yet, however,

409

Energy Dependence of $K/\\pi$, $p/\\pi$, 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 \

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

2014-01-01T23:59:59.000Z

410

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

411

LHC Results on Charmonium in Heavy Ions  

E-Print Network [OSTI]

In heavy-ion collisions at high energies, the quantum chromodynamics (QCD) predicts the production of the deconfined quark-gluon plasma (QGP) state. Quarkonia ($c\\bar{c}$ or $b\\bar{b}$ bound states) are a useful means to probe QGP and to investigate the behavior of QCD under the high parton-density environment. Up to now, the large hadron collider (LHC) at CERN provided two runs for PbPb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV in the years 2010 and 2011. The ALICE, ATLAS, and CMS experiments at LHC have analyzed the yields and spectra of the $J/\\psi$ and $\\Upsilon$ families. In this article, we review particularly the recent charmonium results in PbPb collisions at LHC from the 2010 run.

Byungsik Hong; on behalf of the ALICE; ATLAS; CMS collaborations

2012-08-08T23:59:59.000Z

412

Associated production of a top quark and a charged Higgs boson  

Science Journals Connector (OSTI)

We compute the inclusive and differential cross sections for the associated production of a top quark along with a charged Higgs boson at hadron colliders to next-to-leading order (NLO) in perturbative quantum chromodynamics (QCD) and in supersymmetric QCD. For small Higgs boson masses we include top-quark pair production diagrams with subsequent top-quark decay into a bottom quark and a charged Higgs boson. We compare the NLO differential cross sections obtained in the bottom parton picture with those for the gluon-initiated production process and find good agreement. The effects of supersymmetric loop contributions are explored. Only the corrections to the Yukawa coupling are sizable in the potential discovery region at the CERN Large Hadron Collider (LHC). All expressions and numerical results are fully differential, permitting selections on the momenta of both the top quark and the charged Higgs boson.

Edmond L Berger; Tao Han; Jing Jiang; Tilman Plehn

2005-06-28T23:59:59.000Z

413

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

414

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

415

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

2009-10-12T23:59:59.000Z

416

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

417

Quantum Algorithm for SAT Problem and Quantum Mutual Entropy  

E-Print Network [OSTI]

It is von Neumann who opened the window for today's Information epoch. He defined quantum entropy including Shannon's information more than 20 years ahead of Shannon, and he introduced a concept what computation means mathematically. In this paper I will report two works that we have recently done, one of which is on quantum algorithum in generalized sense solving the SAT problem (one of NP complete problems) and another is on quantum mutual entropy properly describing quantum communication processes.

Masanori Ohya

2004-06-29T23:59:59.000Z

418

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

419

Microwave Quantum Illumination  

E-Print Network [OSTI]

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or 'quantum radar', is shown to be superior to that of any classical microwave radar of equal transmitted energy.

Shabir Barzanjeh; Saikat Guha; Christian Weedbrook; David Vitali; Jeffrey H. Shapiro; Stefano Pirandola

2014-10-15T23:59:59.000Z

420

Microwave Quantum Illumination  

E-Print Network [OSTI]

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or 'quantum radar', is shown to be superior to that of any classical microwave radar of equal transmit...

Barzanjeh, Shabir; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

2014-01-01T23:59:59.000Z

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.


421

Consistent Quantum Reasoning  

E-Print Network [OSTI]

Precise rules are developed in order to formalize the reasoning processes involved in standard non-relativistic quantum mechanics, with the help of analogies from classical physics. A classical or quantum description of a mechanical system involves a {\\it framework}, often chosen implicitly, and a {\\it statement} or assertion about the system which is either true or false within the framework with which it is associated. Quantum descriptions are no less ``objective'' than their classical counterparts, but differ from the latter in the following respects: (i) The framework employs a Hilbert space rather than a classical phase space. (ii) The rules for constructing meaningful statements require that the associated projectors commute with each other and, in the case of time-dependent quantum histories, that consistency conditions be satisfied. (iii) There are incompatible frameworks which cannot be combined, either in constructing descriptions or in making logical inferences about them, even though any one of these frameworks may be used separately for describing a particular physical system. A new type of ``generalized history'' is introduced which extends previous proposals by Omn\\`es, and Gell-Mann and Hartle, and a corresponding consistency condition which does not involve density matrices or single out a direction of time. Applications which illustrate the formalism include: measurements of spin, two-slit diffraction, and the emergence of the classical world from a fully quantum description.

Robert B. Griffiths

1995-05-17T23:59:59.000Z

422

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

423

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

424

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

425

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

426

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

427

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

428

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

429

The Invisible Quantum Barrier  

E-Print Network [OSTI]

We construct the invisible quantum barrier which represents the phenomenon of quantum reflection using the available data. We use the Abel equation to invert the data. The resulting invisible quantum barrier is double-valued in both axes. We study this invisible barrier in the case of atom and Bose-Einstein Condensate reflection from a solid silicon surface. A time-dependent, one-spatial dimension Gross-Pitaevskii equation is solved for the BEC case. We found that the BEC behaves very similarly to the single atom except for size effects, which manifest themselves in a maximum in the reflectivity at small distances from the wall. The effect of the atom-atom interaction on the BEC reflection and correspondingly on the invisible barrier is found to be appreciable at low velocities and comparable to the finite size effect. The trapping of ultracold atoms or BEC between two walls is discussed.

J. X. de Carvalho; M. S. Hussein; Weibin Li

2008-02-06T23:59:59.000Z

430

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

431

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

432

Viscosity of Quantum Hall Fluids  

Science Journals Connector (OSTI)

The viscosity of quantum fluids with an energy gap at zero temperature is related to the adiabatic curvature on the space parametrizing flat background metrics. For quantum Hall fluids on two-dimensional tori, the quantum viscosity is computed. It turns out to be isotropic, constant, and proportional to the magnetic field strength.

J. E. Avron; R. Seiler; P. G. Zograf

1995-07-24T23:59:59.000Z

433

Shared access to quantum information  

Science Journals Connector (OSTI)

It is shown that quantum mechanics allows a qubit to be transferred so that it can be accessed symmetrically by two observers. These can then decide later which one is to take possession of the quantum information. The process is not fully successful, but a failed experiment may allow the retention of the quantum information for use in a subsequent operation.

Stig Stenholm and Erika Andersson

2000-09-11T23:59:59.000Z

434

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

435

Authentication of quantum messages.  

SciTech Connect (OSTI)

Authentication is a well-studied area of classical cryptography: a sender A and a receiver B sharing a classical private key want to exchange a classical message with the guarantee that the message has not been modified or replaced by a dishonest party with control of the communication line. In this paper we study the authentication of messages composed of quantum states. We give a formal definition of authentication in the quantum setting. Assuming A and B have access to an insecure quantum channel and share a private, classical random key, we provide a non-interactive scheme that both enables A to encrypt and authenticate (with unconditional security) an m qubit message by encoding it into m + s qubits, where the probability decreases exponentially in the security parameter s. The scheme requires a private key of size 2m + O(s). To achieve this, we give a highly efficient protocol for testing the purity of shared EPR pairs. It has long been known that learning information about a general quantum state will necessarily disturb it. We refine this result to show that such a disturbance can be done with few side effects, allowing it to circumvent cryptographic protections. Consequently, any scheme to authenticate quantum messages must also encrypt them. In contrast, no such constraint exists classically: authentication and encryption are independent tasks, and one can authenticate a message while leaving it publicly readable. This reasoning has two important consequences: On one hand, it allows us to give a lower bound of 2m key bits for authenticating m qubits, which makes our protocol asymptotically optimal. On the other hand, we use it to show that digitally signing quantum states is impossible, even with only computational security.

Barnum, Howard; Crépeau, Jean-Claude; Gottesman, D. (Daniel); Smith, A. (Adam); Tapp, Alan

2001-01-01T23:59:59.000Z

436

Electric Field effects on quantum correlations in semiconductor quantum dots  

E-Print Network [OSTI]

We study the effect of external electric bias on the quantum correlations in the array of optically excited coupled semiconductor quantum dots. The correlations are characterized by the quantum discord and concurrence and are observed using excitonic qubits. We employ the lower bound of concurrence for thermal density matrix at different temperatures. The effect of the F\\"orster interaction on correlations will be studied. Our theoretical model detects nonvanishing quantum discord when the electric field is on while concurrence dies, ensuring the existence of nonclassical correlations as measured by the quantum discord.

S. Shojaei; M. Mahdian; R. Yousefjani

2012-05-01T23:59:59.000Z

437

Quantum convolutional stabilizer codes  

E-Print Network [OSTI]

and computer scientists such as Charles H. Bennett of the IBM Thomas J. Watson Research Center, Paul A. Benio® of Argonne National Laboratory in Illinois, David Deutsch of the University of Oxford, and Richard P. Feynman of California Institute of Technology... are inherently quantum mechanical in nature, not classical. Feynman was among the ¯rst to attempt to provide an answer to this question by producing an abstract model in 1982 that showed how a quantum system could be used to do computations. Later, in 1985...

Chinthamani, Neelima

2004-09-30T23:59:59.000Z

438

Thermodynamics of quantum lightspheres  

E-Print Network [OSTI]

Lightspheres, surfaces where massless particles are confined in closed orbits, are expected to be common astrophysical structures surrounding ultra-compact objects. In this paper a semi-classical treatment to photons in a lightspheres is proposed. We consider the quantum Maxwell field and derive its energy spectra. A thermodynamic approach for the quantum lightsphere is explored. Within this treatment, an expression for the spectral energy density of the emitted radiation is presented. Our results suggest that lightspheres populated by photons, when thermalized with their environment, have non-usual thermodynamic properties, which could lead to distinct observational signatures.

M. C. Baldiotti; Walace S. Elias; C. Molina; Thiago S. Pereira

2014-10-07T23:59:59.000Z

439

Thermodynamics of quantum lightspheres  

E-Print Network [OSTI]

Lightspheres, surfaces where massless particles are confined in closed orbits, are expected to be common astrophysical structures surrounding ultra-compact objects. In this paper a semi-classical treatment to photons in a lightspheres is proposed. We consider the quantum Maxwell field and derive its energy spectra. A thermodynamic approach for the quantum lightsphere is explored. Within this treatment, an expression for the spectral energy density of the emitted radiation is presented. Our results suggest that lightspheres populated by photons, when thermalized with their environment, have non-usual thermodynamic properties, which could lead to distinct observational signatures.

Baldiotti, M C; Molina, C; Pereira, Thiago S

2014-01-01T23:59:59.000Z

440

Types of quantum information  

E-Print Network [OSTI]

Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in quantum terms, of ``classical information.'' Various examples (some updating earlier work) are given of theorems which relate different incompatible kinds of information, and thus have no counterparts in classical information theory.

Robert B. Griffiths

2007-07-25T23:59:59.000Z

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.


441

Information and quantum nonseparability  

Science Journals Connector (OSTI)

An information-theoretic inequality analogous to the well-known result of Bell [Physics 1, 195 (1964)] is formulated using the concept of information distance. This inequality, like Bell’s, is true for all local-hidden-variable theories, but not for quantum mechanics. The metric space structure of this new inequality suggests a reformulation of familiar Bell inequalities in terms of a ‘‘covariance distance.’’ Quantum nonseparability can be demonstrated through violations of these inequalities even in cases where the correlation between two systems is extremely weak. The connection between nonseparability and complementarity is also briefly discussed in this paper.

B. W. Schumacher

1991-12-01T23:59:59.000Z

442

Types of quantum information  

Science Journals Connector (OSTI)

Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in quantum terms, of “classical information.” Various examples (some updating earlier work) are given of theorems which relate different incompatible kinds of information, and thus have no counterparts in classical information theory.

Robert B. Griffiths

2007-12-21T23:59:59.000Z

443

Quantum thermodynamic cooling cycle  

E-Print Network [OSTI]

The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

Palao, J P; Gordon, J M; Palao, Jose P.; Kosloff, Ronnie; Gordon, Jeffrey M.

2001-01-01T23:59:59.000Z

444

Quantum thermodynamic cooling cycle  

E-Print Network [OSTI]

The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

Jose P. Palao; Ronnie Kosloff; Jeffrey M. Gordon

2001-06-08T23:59:59.000Z

445

Quantum Decision Theory  

E-Print Network [OSTI]

We argue that, contrary to conventional wisdom, decision theory is not invariant to the physical environment in which a decision is made. Specifically, we show that a decision maker (DM) with access to quantum information resources may be able to do strictly better than a DM with access only to classical information resources. In this respect, our findings are somewhat akin to those in computer science that have established the superiority of quantum over classical algorithms for certain problems. We treat three kinds of decision tree (Kuhn [1950], [1953]): Kuhn trees in which the DM does or does not have perfect recall, and non-Kuhn trees.

Adam Brandenburger; Pierfrancesco La Mura

2011-07-01T23:59:59.000Z

446

Fields and Quantum Mechanics  

E-Print Network [OSTI]

The quantum field theories (QFT) constructed in [1,2] include phenomenology of interest. The constructions approximate: scattering by $1/r$ and Yukawa potentials in non-relativistic approximations; and the first contributing order of the Feynman series for Compton scattering. To have a semi-norm, photon states are constrained to transverse polarizations and for Compton scattering, the constructed cross section deviates at large momentum exchanges from the cross section prediction of the Feynman rules. Discussion includes the incompatibility of canonical quantization with the constructed interacting fields, and the role of interpretations of quantum mechanics in realizing QFT.

Glenn Eric Johnson

2014-12-21T23:59:59.000Z

447

Characterizing quantum coherence  

Science Journals Connector (OSTI)

For a system with canonical variables x and p, [x,p]=i?, we associate with each density operator ? an x coherence ?x and a p coherence ?p which specify, respectively, the characteristic distance and momentum range over which the underlying quantum-mechanical nature of the ensemble cannot be neglected. These coherences are less than or equal to the associated uncertainties ?x??x, ?p??p; so the ratios cx??x/?x, cp??p/?p give measures of the quantum character of the ensemble with respect to x and p. Examples are presented.

J. E. Sipe and N. Arkani-Hamed

1992-09-01T23:59:59.000Z

448

Optimal Quantum Pumps  

E-Print Network [OSTI]

We study adiabatic quantum pumps on time scales that are short relative to the cycle of the pump. In this regime the pump is characterized by the matrix of energy shift which we introduce as the dual to Wigner's time delay. The energy shift determines the charge transport, the dissipation, the noise and the entropy production. We prove a general lower bound on dissipation in a quantum channel and define optimal pumps as those that saturate the bound. We give a geometric characterization of optimal pumps and show that they are noiseless and transport integral charge in a cycle. Finally we discuss an example of an optimal pump related to the Hall effect.

J. E. Avron; A. Elgart; G. M. Graf; L. Sadun

2001-07-12T23:59:59.000Z

449

Universal Quantum Circuits  

E-Print Network [OSTI]

We define and construct efficient depth-universal and almost-size-universal quantum circuits. Such circuits can be viewed as general-purpose simulators for central classes of quantum circuits and can be used to capture the computational power of the circuit class being simulated. For depth we construct universal circuits whose depth is the same order as the circuits being simulated. For size, there is a log factor blow-up in the universal circuits constructed here. We prove that this construction is nearly optimal.

Debajyoti Bera; Stephen Fenner; Frederic Green; Steve Homer

2008-04-15T23:59:59.000Z

450

Factorization and resummation for collinear poles in QCD amplitudes  

SciTech Connect (OSTI)

We study the origin of subleading soft and collinear poles of form factors and amplitudes in dimensionally-regulated massless gauge theories. In the case of form factors of fundamental fields, these poles originate from a single function of the coupling, denoted G({alpha}{sub s}), depending on both the spin and gauge quantum numbers of the field. We relate G({alpha}{sub s}) to gauge-theory matrix elements involving the gluon field strength. We then show that G({alpha}{sub s}) is the sum of three terms: a universal eikonal anomalous dimension, a universal non-eikonal contribution, given by the coefficient B{sub {delta}}({alpha}{sub s}) of {delta}(1-z) in the collinear evolution kernel, and a process-dependent short-distance coefficient function, which does not contribute to infrared poles. Using general results on the factorization of soft and collinear singularities in fixed-angle massless gauge theory amplitudes, we conclude that all such singularities are captured by the eikonal approximation, supplemented only by the knowledge of B{sub {delta}}({alpha}{sub s}). We explore the consequences of our results for conformal gauge theories, where in particular we find a simple exact relation between the form factor and the cusp anomalous dimension.

Dixon, Lance J.; Magnea, Lorenzo; Sterman, George

2008-05-28T23:59:59.000Z

451

Quantum Robot: Structure, Algorithms and Applications  

E-Print Network [OSTI]

A kind of brand-new robot, quantum robot, is proposed through fusing quantum theory with robot technology. Quantum robot is essentially a complex quantum system and it is generally composed of three fundamental parts: MQCU (multi quantum computing units), quantum controller/actuator, and information acquisition units. Corresponding to the system structure, several learning control algorithms including quantum searching algorithm and quantum reinforcement learning are presented for quantum robot. The theoretic results show that quantum robot can reduce the complexity of O(N^2) in traditional robot to O(N^(3/2)) using quantum searching algorithm, and the simulation results demonstrate that quantum robot is also superior to traditional robot in efficient learning by novel quantum reinforcement learning algorithm. Considering the advantages of quantum robot, its some potential important applications are also analyzed and prospected.

Dao-Yi Dong; Chun-Lin Chen; Chen-Bin Zhang; Zong-Hai Chen

2005-06-18T23:59:59.000Z

452

Quantum cost for sending entanglement  

E-Print Network [OSTI]

Establishing quantum entanglement between two distant parties is an essential step of many protocols in quantum information processing. One possibility for providing long-distance entanglement is to create an entangled composite state within a lab and then physically send one subsystem to a distant lab. However, is this the "cheapest" way? Here, we investigate the minimal "cost" that is necessary for establishing a certain amount of entanglement between two distant parties. We prove that this cost is intrinsically quantum, and is specified by quantum correlations. Our results provide an optimal protocol for entanglement distribution and show that quantum correlations are the essential resource for this task.

Alexander Streltsov; Hermann Kampermann; Dagmar Bruß

2012-03-06T23:59:59.000Z

453

Classicality of quantum information processing  

Science Journals Connector (OSTI)

The ultimate goal of the classicality program is to quantify the amount of quantumness of certain processes. Here, classicality is studied for a restricted type of process: quantum information processing (QIP). Under special conditions, one can force some qubits of a quantum computer into a classical state without affecting the outcome of the computation. The minimal set of conditions is described and its structure is studied. Some implications of this formalism are the increase of noise robustness, a proof of the quantumness of mixed state quantum computing, and a step forward in understanding the very foundation of QIP.

David Poulin

2002-04-04T23:59:59.000Z

454

National Computational Infrastructure for Lattice Gauge Theory  

SciTech Connect (OSTI)

SciDAC-2 Project The Secret Life of Quarks: National Computational Infrastructure for Lattice Gauge Theory, from March 15, 2011 through March 14, 2012. The objective of this project is to construct the software needed to study quantum chromodynamics (QCD), the theory of the strong interactions of sub-atomic physics, and other strongly coupled gauge field theories anticipated to be of importance in the energy regime made accessible by the Large Hadron Collider (LHC). It builds upon the successful efforts of the SciDAC-1 project National Computational Infrastructure for Lattice Gauge Theory, in which a QCD Applications Programming Interface (QCD API) was developed that enables lattice gauge theorists to make effective use of a wide variety of massively parallel computers. This project serves the entire USQCD Collaboration, which consists of nearly all the high energy and nuclear physicists in the United States engaged in the numerical study of QCD and related strongly interacting quantum field theories. All software developed in it is publicly available, and can be downloaded from a link on the USQCD Collaboration web site, or directly from the github repositories with entrance linke http://usqcd-software.github.io

Brower, Richard C.

2014-04-15T23:59:59.000Z

455

Heavy quark production in the black hole evaporation at LHC  

SciTech Connect (OSTI)

The understanding of Quantum Chromodynamics (QCD) and Quantum Gravity are currently two of the main open questions in Physics. In order to understand these problems some authors proposed the existence of extra dimensions in the Nature. These extra dimensions would be compacted and not visible on the macroscopic world, but the effects would be manifest in ultrarelativistic colision process. In particular, black holes (BH) could be produced in proton-proton colisions in the Large Hadron Collider (LHC) and in future colliders. The BH is an object characterized by its mass and temperature wich also characterizes the evaporation process. All kind of particle should be produced in this process. Our goal in this contribution is to study the BH production in proton - proton collisions at LHC and its evaporation rate in heavy quarks. We present our estimate considering two scenarios (with and without trapped energy corrections) and compare our predictions with those obtained using perturbative QCD. Our results demonstrate that in both scenarios the charm and bottom production in the BH evaporation are smaller than the QCD prediction at LHC. In contrast, the top production is similar or larger than the QCD prediction, if the trapped energy corrections are disregarded.

Thiel, M.; Goncalves, V. P.; Sauter, W. K. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas (Brazil)

2013-03-25T23:59:59.000Z

456

New Quantum Structures  

Science Journals Connector (OSTI)

...the thermal diffusion ofthe deposited...this thermal diffusion. Thus, LSL...low-density electron gas is predicted...microscope image oflateral superlattice...producing highly anisotropic electrical...broad span of infrared energies with...These wells and gases constitute...enhanced quantum-based electronic...

MANI SUNDARAM; SCOTT A. CHALMERS; PETER F. HOPKINS; ARTHUR C. GOSSARD

1991-11-29T23:59:59.000Z

457

Engineering the Quantum Foam  

E-Print Network [OSTI]

In 1990 Alcubierre, within the General Relativity model for space-time, proposed a scenario for `warp drive' faster than light travel, in which objects would achieve such speeds by actually being stationary within a bubble of space which itself was moving through space, the idea being that the speed of the bubble was not itself limited by the speed of light. However that scenario required exotic matter to stabilise the boundary of the bubble. Here that proposal is re-examined within the context of the new modelling of space in which space is a quantum system, viz a quantum foam, with on-going classicalisation. This model has lead to the resolution of a number of longstanding problems, including a dynamical explanation for the so-called `dark matter' effect. It has also given the first evidence of quantum gravity effects, as experimental data has shown that a new dimensionless constant characterising the self-interaction of space is the fine structure constant. The studies here begin the task of examining to what extent the new spatial self-interaction dynamics can play a role in stabilising the boundary without exotic matter, and whether the boundary stabilisation dynamics can be engineered; this would amount to quantum gravity engineering.

Reginald T. Cahill

2005-06-06T23:59:59.000Z

458

Quantum Bidding in Bridge  

Science Journals Connector (OSTI)

Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game—bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow). We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2?1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.

Sadiq Muhammad; Armin Tavakoli; Maciej Kurant; Marcin Paw?owski; Marek ?ukowski; Mohamed Bourennane

2014-06-12T23:59:59.000Z

459

Quantum Gauss Jordan Elimination  

E-Print Network [OSTI]

In this paper we construct the Quantum Gau\\ss Jordan Elimination (QGJE) Algorithm and estimate the complexity time of computation of Reduced Row Echelon Form (RREF) of an $N\\times N$ matrix using QGJE procedure. The main theorem asserts that QGJE has computation time of order $2^{N/2}$.

Do Ngoc Diep; Do Hoang Giang

2005-11-07T23:59:59.000Z

460

Hybrid Quantum Computation  

E-Print Network [OSTI]

We present a hybrid model of the unitary-evolution-based quantum computation model and the measurement-based quantum computation model. In the hybrid model part of a quantum circuit is simulated by unitary evolution and the rest by measurements on star graph states, thereby combining the advantages of the two standard quantum computation models. In the hybrid model, a complicated unitary gate under simulation is decomposed in terms of a sequence of single-qubit operations, the controlled-Z gates, and multi-qubit rotations around the z-axis. Every single-qubit- and the controlled-Z gate are realized by a respective unitary evolution, and every multi-qubit rotation is executed by a single measurement on a required star graph state. The classical information processing in our model only needs an information flow vector and propagation matrices. We provide the implementation of multi-control gates in the hybrid model. They are very useful for implementing Grover's search algorithm, which is studied as an illustrating example.

Arun Sehrawat; Daniel Zemann; Berthold-Georg Englert

2010-08-06T23:59:59.000Z

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

Compatibility of quantum states  

SciTech Connect (OSTI)

We introduce a measure of compatibility between quantum states--the likelihood that two density matrices describe the same object. Our measure is motivated by two elementary requirements, which lead to a natural definition. We list some properties of this measure, and discuss its relation to the problem of combining two observers' states of knowledge.

Poulin, David; Blume-Kohout, Robin [Theoretical Division, Los Alamos National Laboratory, MS-B210, Los Alamos, New Mexico 87545 (United States)

2003-01-01T23:59:59.000Z

462

Compatibility of quantum states  

Science Journals Connector (OSTI)

We introduce a measure of compatibility between quantum states—the likelihood that two density matrices describe the same object. Our measure is motivated by two elementary requirements, which lead to a natural definition. We list some properties of this measure, and discuss its relation to the problem of combining two observers’ states of knowledge.

David Poulin and Robin Blume-Kohout

2003-01-15T23:59:59.000Z

463

Phenomenological Quantum Gravity  

E-Print Network [OSTI]

Planck scale physics represents a future challenge, located between particle physics and general relativity. The Planck scale marks a threshold beyond which the old description of spacetime breaks down and conceptually new phenomena must appear. In the last years, increased efforts have been made to examine the phenomenology of quantum gravity, even if the full theory is still unknown.

S. Hossenfelder

2006-11-01T23:59:59.000Z

464

Quantum Interferometric Sensors  

E-Print Network [OSTI]

Quantum entanglement has the potential to revolutionize the entire field of interferometric sensing by providing many orders of magnitude improvement in interferometer sensitivity. The quantum-entangled particle interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like $1/\\sqrt{N}$, where $N$ is the number of particles passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of $\\sqrt{N}$ to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. This effect can translate into a tremendous science pay-off for space missions. For example, one application of this new effect is to fiber optical gyroscopes for deep-space inertial guidance and tests of General Relativity (Gravity Probe B). Another application is to ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively. Other applications are to Satellite-to-Satellite laser Interferometry (SSI) proposed for the next generation Gravity Recovery And Climate Experiment (GRACE II).

Kishore T. Kapale; Leo D. Didomenico; Hwang Lee; Pieter Kok; Jonathan P. Dowling

2005-07-15T23:59:59.000Z

465

Resummed Quantum Gravity  

E-Print Network [OSTI]

We present the current status of the a new approach to quantum general relativity based on the exact resummation of its perturbative series as that series was formulated by Feynman. We show that the resummed theory is UV finite and we present some phenomenological applications as well.

B. F. L. Ward

2006-10-18T23:59:59.000Z

466

Berry Phase Quantum Thermometer  

E-Print Network [OSTI]

We show how Berry phase can be used to construct an ultra-high precision quantum thermometer. An important advantage of our 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.

Martin-Martinez, E; Mann, R B; Fuentes, I

2011-01-01T23:59:59.000Z

467

Berry Phase Quantum Thermometer  

E-Print Network [OSTI]

We show how Berry phase can be used to construct an ultra-high precision quantum thermometer. An important advantage of our 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.

E. Martin-Martinez; A. Dragan; R. B. Mann; I. Fuentes

2013-05-28T23:59:59.000Z

468

Quantum-enhanced absorption refrigerators  

E-Print Network [OSTI]

Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators.

Luis A. Correa; José P. Palao; Daniel Alonso; Gerardo Adesso

2013-08-19T23:59:59.000Z

469

New weakly-coupled forces hidden in low-energy QCD  

E-Print Network [OSTI]

Is it possible to detect a new weakly-coupled force at the QCD scale that interacts primarily with quarks? This work investigates experimental signatures of a new MeV - GeV gauge boson that couples to baryon number, with attention to the 100 MeV - GeV mass range that is the regime of nonperturbative QCD. Such a state can be searched for in rare radiative decays of light mesons ($\\eta, \\eta^\\prime, \\phi, \\omega$) as a $\\pi^0 \\gamma$ resonance, which is its leading decay mode from 140 - 620 MeV. This is a new discovery window for forces beyond the Standard Model that is not covered by existing dark photon searches.

Sean Tulin

2014-04-16T23:59:59.000Z

470

New weakly-coupled forces hidden in low-energy QCD  

E-Print Network [OSTI]

Is it possible to detect a new weakly-coupled force at the QCD scale that interacts primarily with quarks? This work investigates experimental signatures of a new MeV - GeV gauge boson that couples to baryon number, with attention to the 100 MeV - GeV mass range that is the regime of nonperturbative QCD. Such a state can be searched for in rare radiative decays of light mesons ($\\eta, \\eta^\\prime, \\phi, \\omega$) as a $\\pi^0 \\gamma$ resonance, which is its leading decay mode from 140 - 620 MeV. This is a new discovery window for forces beyond the Standard Model that is not covered by existing dark photon searches.

Tulin, Sean

2014-01-01T23:59:59.000Z

471

Local CP-violation and electric charge separation by magnetic fields from lattice QCD  

E-Print Network [OSTI]

We study local CP-violation on the lattice by measuring the local correlation between the topological charge density and the electric dipole moment of quarks, induced by a constant external magnetic field. This correlator is found to increase linearly with the external field, with the coefficient of proportionality depending only weakly on temperature. Results are obtained on lattices with various spacings, and are extrapolated to the continuum limit after the renormalization of the observables is carried out. This renormalization utilizes the gradient flow for the quark and gluon fields. Our findings suggest that the strength of local CP-violation in QCD with physical quark masses is about an order of magnitude smaller than a model prediction based on nearly massless quarks in domains of constant gluon backgrounds with topological charge. We also show numerical evidence that the observed local CP-violation correlates with spatially extended electric dipole structures in the QCD vacuum.

G. S. Bali; F. Bruckmann; G. Endrodi; Z. Fodor; S. D. Katz; A. Schafer

2014-01-16T23:59:59.000Z

472

Magnetic structure of isospin-asymmetric QCD matter in neutron stars  

E-Print Network [OSTI]

We study QCD under the influence of background magnetic fields and isospin chemical potentials using lattice simulations. This setup exhibits a sign problem which is circumvented using a Taylor-expansion in the magnetic field. The ground state of the system in the pion condensation phase is found to exhibit a pronounced diamagnetic response. We elaborate on how this diamagnetism may contribute to the pressure balance in the inner core of strongly magnetized neutron stars. In addition we show that the onset of pion condensation shifts to larger chemical potentials due to the enhancement of the charged pion mass for growing magnetic fields. Finally, we sketch the magnetic structure of the QCD phase diagram in the temperature-isospin chemical potential plane.

G. Endrodi

2014-07-04T23:59:59.000Z

473

Onset Transition to Cold Nuclear Matter from Lattice QCD with Heavy Quarks to $?^4$  

E-Print Network [OSTI]

We present results of our ongoing studies of an effective three-dimensional theory of thermal lattice QCD with heavy Wilson quarks. This is done by combined strong coupling and hopping parameter expansions. The full quark determinant of four dimensional lattice QCD is expanded in orders of the hopping parameter $\\kappa$, the dimensional reduction is achieved by integrating over the spatial links. We present the calculation of the effective theory through order $\\kappa^nu^m$ with $n+m=4$. This theory is then used to simulate heavy quarks near the cold and dense limit. For nonzero chemical potential the theory suffers from a sign problem, wich is avoided by employing stochastical quantisation. Continuum extrapolated results for the onset of nuclear matter are shown and the region of convergence of the effective theory is discussed.

Jens Langelage; Mathias Neuman; Owe Philipsen

2013-11-18T23:59:59.000Z

474

Recent Results from PHENIX Experiment at RHIC: Exploring the QCD Medium  

E-Print Network [OSTI]

We review some important results from the PHENIX experiment at RHIC. They were obtained in a unique environment for studying QCD bulk matter at temperatures and densities that sur- pass the limits where hadrons exist as individual entities, so raising to prominence the quark- gluon degrees of freedom. We present measurements of nuclear modification factors for neutral pions, light favors (strange hadrons), direct-photons and non-photonic electrons from decays of particles carrying charm or beauty quarks. We interpret the large suppression of hadron produc- tion at high transverse momenta as resulting from a large energy loss by the precursor parton on its path through the dense matter, primarily driven by gluon radiation. This dense QCD matter responds to energy loss in a pattern consistent with that expected from a hydrodynamic fluid. Further, its elliptic flow measurements suggest that the hadronization of bulk partonic matter exhibits collectivity with effective partonic degrees of freedom. The results are...

Nouicer, Rachid

2012-01-01T23:59:59.000Z

475

Semileptonic B and Lambda_b Decays and Local Duality in QCD  

E-Print Network [OSTI]

The inclusive and exclusive semileptonic decay distributions for b -> c decay are computed in the Shifman-Voloshin limit. The inclusive decay distributions (computed using an operator product expansion) depend on quark masses, and the exclusive decay distributions depend on hadron masses. Nevertheless, we show explicitly how the first two terms in the 1/m expansion match between the inclusive and exclusive decays. Agreement between the inclusive and exclusive decay rates requires a minimum smearing region of size Lambda_QCD before local duality holds in QCD. The alpha_s corrections to the inclusive and exclusive decay rates are also shown to agree to order (log m)/m^2. The alpha_s/m^2 corrections are used to obtain the alpha_s correction to Bjorken's inequality on the slope of the Isgur-Wise function.

C. Glenn Boyd; Benjamin Grinstein; Aneesh V. Manohar

1995-11-03T23:59:59.000Z

476

A resummed perturbative estimate for the quarkonium spectral function in hot QCD  

E-Print Network [OSTI]

By making use of the finite-temperature real-time static potential that was introduced and computed to leading non-trivial order in Hard Thermal Loop resummed perturbation theory in recent work, and solving numerically a Schr\\"odinger-type equation, we estimate the quarkonium (in practice, bottomonium) contribution to the spectral function of the electromagnetic current in hot QCD. The spectral function shows a single resonance peak which becomes wider and then disappears as the temperature is increased beyond 450 MeV or so. This behaviour can be compared with recently attempted lattice reconstructions of the same quantity, based on the ``maximum entropy method'', which generically show several peaks. We also specify the dependence of our results on the spatial momentum of the electromagnetic current, as well as on the baryon chemical potential characterising the hot QCD plasma.

M. Laine

2007-06-12T23:59:59.000Z

477

Lee-Yang zero distribution of high temperature QCD and Roberge-Weiss phase transition  

E-Print Network [OSTI]

Canonical partition functions and Lee-Yang zeros of QCD at finite density and high temperature are studied. We present analytic derivation of the canonical partition functions and Lee-Yang zeros based on the free energy in the Stefan-Boltzmann limit using a saddle point approximation. We also perform lattice QCD simulation in a canonical approach using the fugacity expansion of the fermion determinant, and carefully examine its reliability. By comparing the analytic and numerical results, we conclude that the canonical partition functions follow the Gaussian distribution of the baryon number, and the accumulation of Lee-Yang zeros of these canonical partition functions exhibit the first order Roberge-Weiss phase transition. We discuss the validity and applicable range of the result, and its implications both for theoretical and experimental studies.

Nagata, Keitaro; Nakamura, Atsushi; Nishigaki, Shinsuke M

2014-01-01T23:59:59.000Z

478

Lee-Yang zero distribution of high temperature QCD and Roberge-Weiss phase transition  

E-Print Network [OSTI]

Canonical partition functions and Lee-Yang zeros of QCD at finite density and high temperature are studied. We present analytic derivation of the canonical partition functions and Lee-Yang zeros based on the free energy in the Stefan-Boltzmann limit using a saddle point approximation. We also perform lattice QCD simulation in a canonical approach using the fugacity expansion of the fermion determinant, and carefully examine its reliability. By comparing the analytic and numerical results, we conclude that the canonical partition functions follow the Gaussian distribution of the baryon number, and the accumulation of Lee-Yang zeros of these canonical partition functions exhibit the first order Roberge-Weiss phase transition. We discuss the validity and applicable range of the result, and its implications both for theoretical and experimental studies.

Keitaro Nagata; Kouji Kashiwa; Atsushi Nakamura; Shinsuke M. Nishigaki

2014-10-03T23:59:59.000Z

479

Synthesis of linear quantum stochastic systems via quantum feedback networks  

E-Print Network [OSTI]

Recent theoretical and experimental investigations of coherent feedback control, the feedback control of a quantum system with another quantum system, has raised the important problem of how to synthesize a class of quantum systems, called the class of linear quantum stochastic systems, from basic quantum optical components and devices in a systematic way. The synthesis theory sought in this case can be naturally viewed as a quantum analogue of linear electrical network synthesis theory and as such has potential for applications beyond the realization of coherent feedback controllers. In earlier work, Nurdin, James and Doherty have established that an arbitrary linear quantum stochastic system can be realized as a cascade connection of simpler one degree of freedom quantum harmonic oscillators, together with a direct interaction Hamiltonian which is bilinear in the canonical operators of the oscillators. However, from an experimental perspective and based on current methods and technologies, direct interaction Hamiltonians are challenging to implement for systems with more than just a few degrees of freedom. In order to facilitate more tractable physical realizations of these systems, this paper develops a new synthesis algorithm for linear quantum stochastic systems that relies solely on field-mediated interactions, including in implementation of the direct interaction Hamiltonian. Explicit synthesis examples are provided to illustrate the realization of two degrees of freedom linear quantum stochastic systems using the new algorithm.

H. I. Nurdin

2009-05-06T23:59:59.000Z

480

Quo Vadis Quantum Mechanics?  

Science Journals Connector (OSTI)

Quantum mechanics is one of the most successful theoretical structures in all of science. Developed between 1925-26 to explain the optical spectrum of atoms, the theory over the succeeding 80 years has been extended, first to quantum field theories, gauge field theories, and now even string theory. It is used every day by thousands of physicists to calculate physical phenomena to exquisite precision, with no ambiguity in the results. To claim that this is a theory which is not understood by those physicists is absurd. And yet, as eminent a physicist as Richard Feynman, who did as much as anyone else to extend quantum theory to field theories and was a master at producing those exquisite calculations, could say that anyone who claimed they understood quantum theory clearly did not understand quantum theory. One hundred years ago Einstein postulated one of the most unsettling features of the theory, the wave-particle duality, with his particulate explanation for light of the photoelectric effect, and an explanation which was in direct conflict with Maxwell's brilliant development of a wave, or field, theory of light. Einstein believed that the particulate nature would ultimately be explainable by some sort of non-linear theory of electromagnetism, and was outraged by the acceptance of the community of the probabilistic quantum theory. His programme was of course dealt a (near?) fatal blow by Bell's discovery that the three desiderata - a theory which agrees with experiment, a theory which is local in its effects, and a theory in which nature, at its heart, is not probabilistic - are incompatible. That discomfort felt by Einstein and by Feynman is felt by numerous other people as well. This discomfort is heightened by the fact that the theory of gravity, another of Einstein's great achievements, has resisted all efforts at reconciliation with quantum mechanics. This book explores that discomfort, and tries to pin down what the locus of that discomfort is. For many, the locus is in the probabilistic nature at the heart of the theory. Nature should surely, at some fundamental level, know what it is doing. The photon, despite our inability to measure it, should know where it is and how fast it is going. The papers by t'Hooft, Hiley, and Smolin fall into this camp. Some suspect that the macroscopic world of our immediate sense experiences, and the microscopic world of quantum phenomena, are genuinely different, that the fundamental conceptual nature of physics changes from one to the other, with some unknown boundary between them. Penrose, in his preface alludes to his speculations on this, as does Leggett to his own speculations in his paper. And a number of articles (e.g., by Hartle, Rovelli, and others) opine that if only everyone looked at quantum mechanics in the right way (their way), it would lose its mystery, and be as natural as Newton's world view. (I myself tend to this position, which is however somewhat tempered by the realization that the clarity and naturalness of my viewpoint is not shared by the others who believe equally firmly in their own natural, clear, but radically different, viewpoint). A number of articles simply examine the counterintuitive nature of quantum theory in general, using it to make sense of time travel (Greenberger and Svozil) and demonstrating the unusual features of induction about the past from present observations within quantum theory (Aharonov and Dolev). The book is not free from rather overblown titles (e.g., 'Liberation and Purification from Classical Prejudice', or 'A Quantum Theory of the Human Person') but those articles nevertheless contain at least amusing speculations. In quantum gravity, the incompatibilities between the two masterstrokes of the twentieth century are highlighted. There is a strong suspicion amongst many in this field that progress in understanding quantum gravity demands a deeper understanding of the great mystery of quantum theory which this book explores. This book is a useful and, at times, fascinating introduction to the flounderings which are taking pla

W G Unruh

2006-01-01T23:59:59.000Z

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481

Magnetic moments of vector, axial, and tensor mesons in lattice QCD  

E-Print Network [OSTI]

We present a calculation of magnetic moments for selected spin-1 mesons using the techniques of lattice QCD. This is carried out by introducing progressively small static magnetic field on the lattice and measuring the linear response of a hadron's mass shift. The calculations are done on $24^4$ quenched lattices using standard Wilson actions, with $\\beta$=6.0 and pion mass down to 500 MeV. The results are compared to those from the form factor method where available.

F. X. Lee; S. Moerschbacher; W. Wilcox

2008-07-25T23:59:59.000Z

482

$J/?$ suppression in heavy ion collsions and the QCD phase transition  

E-Print Network [OSTI]

We suggest that the new regime of $J/\\psi$ suppression in Pb-Pb collisions found by the NA50 experiment at CERN is the result of non-trivial space-time evolution due to specific behavior of the Equation of State (EOS) near the QCD phase transition. We also study another suppression channel, the conversion of $J/\\psi$ into $\\eta_c$ during the late cool hadronic stage, and find it rather inefficient.

E. Shuryak; D. Teaney

1998-01-12T23:59:59.000Z

483

Studies of QCD at the Tevatron with the D0 detector  

SciTech Connect (OSTI)

QCD studies at Fermilab`s Tevatron encompass a rich variety of topics. We present some of the latest results from the D0 experiment including probes of the standard model given by the inclusive jet cross section, the dijet invariant mass spectrum and several studies with direct photons. To complement these probes, we also present new results from precision examinations of the color interactions including studies of color coherence and jet azimuthal decorrelation. 22 refs., 14 figs.

Stephens, R.W. [Texas Univ., Arlington, TX (United States); D0 Collaboration

1996-12-01T23:59:59.000Z

484

The decay constants f(B+) and f(D+) from three-flavor lattice QCD  

SciTech Connect (OSTI)

We present new results for f{sub B+} and f{sub D+} from the MILC 2+1 flavor a = 0.09fm 'fine' lattice. We use clover heavy quarks in the Fermilab interpretation and improved staggered light quarks. Lattice results from partially quenched QCD fix the parameters of staggered chiral perturbation theory which is used in the extrapolation to the physical decay constants.

Bernard, C.; /Washington U., St. Louis; DeTar, Carleton; Levkova, L.; /Utah U.; Di Pierro, Massimo; /DePaul U.; El-Khadra, Aida Xenia; Evans, R.T.; Jain, R.; /Illinois U., Urbana; Freeland, Elizabeth Dawn; /Art Inst. of Chicago; Gottlieb, Steven A.; /Indiana U.; Heller, Urs M.; /APS, New York; Hetrick, James E.; /U. Pacific, Stockton /Fermilab /Simon Fraser U. /Arizona U. /UC, Santa Barbara

2006-01-01T23:59:59.000Z

485

Linear Confinement for Mesons and Nucleons in AdS/QCD  

E-Print Network [OSTI]

By using a new parametrization of the dilaton field and including a cubic term in the bulk scalar potential, we realize linear confinement in both meson and nucleon sectors within the framework of soft-wall AdS/QCD. At the same time this model also correctly incorporate chiral symmetry breaking. We compare our resulting mass spectra with experimental data and find good agreement between them.

Peng Zhang

2010-03-02T23:59:59.000Z

486

The role of quark mass in cold and dense perturbative QCD  

E-Print Network [OSTI]

We consider the equation of state of QCD at high density and zero temperature in perturbation theory to first order in the coupling constant $\\alpha_s$. We compute the thermodynamic potential including the effect of a non-vanishing mass for the strange quark and show that corrections are sizable. Renormalization group running of the coupling and the strange quark mass plays a crucial role. The structure of quark stars is dramatically modified.

Eduardo S. Fraga; Paul Romatschke

2005-05-27T23:59:59.000Z

487

Generalized second law of thermodynamics in QCD ghost f(G) gravity  

E-Print Network [OSTI]

Considering power-law for of scale factor in a flat FRW universe we reported a reconstruction scheme for $f(G)$ gravity based on QCD ghost dark energy. We reconstructed the effective equation of state parameter and observed "quintessence" behavior of the equation of state parameter. Furthermore, considering dynamical apparent horizon as the enveloping horizon of the universe we have observed that the generalized second law of thermodynamics is valid for this reconstructed $f(G)$ gravity.

Chattopadhyay, Surajit

2014-01-01T23:59:59.000Z

488

Generalized second law of thermodynamics in QCD ghost f(G) gravity  

E-Print Network [OSTI]

Considering power-law for of scale factor in a flat FRW universe we reported a reconstruction scheme for $f(G)$ gravity based on QCD ghost dark energy. We reconstructed the effective equation of state parameter and observed "quintessence" behavior of the equation of state parameter. Furthermore, considering dynamical apparent horizon as the enveloping horizon of the universe we have observed that the generalized second law of thermodynamics is valid for this reconstructed $f(G)$ gravity.

Surajit Chattopadhyay

2014-05-30T23:59:59.000Z

489

3D Relativistic Hydrodynamic Computations Using Lattice-QCD-Inspired Equations of State  

E-Print Network [OSTI]

In this communication, we report results of three-dimensional hydrodynamic computations, by using equations of state with a critical end point as suggested by the lattice QCD. Some of the results are an increase of the multiplicity in the mid-rapidity region and a larger elliptic-flow parameter v2. We discuss also the effcts of the initial-condition fluctuations and the continuous emission.

Yogiro Hama; Rone P. G. Andrade; Frederique Grassi; Otavio Socolowski Jr; Takeshi Kodama; Bernardo Tavares; S. S. Padula

2005-10-07T23:59:59.000Z

490

The axial N to Delta transition form factors from Lattice QCD  

E-Print Network [OSTI]

We evaluate the N to Delta axial transition form factors in lattice QCD in the quenched theory, with two degenerate flavors of dynamical Wilson fermions and using domain wall valence fermions with staggered sea quark configurations. We predict the ratio $C_5^A(q^2)/C_3^V(q^2)$ relevant to the parity violating asymmetry and check the validity of the off-diagonal Goldberger-Treiman relation.

C. Alexandrou; Th. Leontiou; J. W. Negele; A. Tsapalis

2006-07-20T23:59:59.000Z

491

Induced Light-Quark Yukawa Couplings as a probe of Low-Energy Dynamics in QCD  

E-Print Network [OSTI]

We examine the heavy-quark-induced Yukawa interaction between light quarks and a light Higgs field, which is facilitated in the chiral limit by the dynamical mass of light quarks anticipated from the chiral-noninvariance of the QCD vacuum. A low-energy estimate of the strong coupling near unity can be obtained from a comparison of the explicit perturbative calculation of the induced Yukawa interaction at zero momentum to a Higgs-low-energy theorem prediction for the same interaction.

M. R. Ahmady; V. Elias; A. H. Fariborz; R. R. Mendel

1996-04-02T23:59:59.000Z

492

Novel QCD Phenomena at the LHC: The Ridge, Digluon-Initiated Subprocesses, Direct Reactions, Non-Universal Antishadowing, and Forward Higgs Production  

E-Print Network [OSTI]

I discuss a number of novel tests of QCD at the LHC, measurements which can illuminate fundamental features of hadron physics. I also review the "Principle of Maximum Conformality" (PMC) which systematically sets the renormalization scale order-by-order in pQCD, eliminating an unnecessary theoretical uncertainty. The PMC allows LHC experiments to test QCD much more precisely, and the sensitivity of LHC measurements to physics beyond the Standard Model is increased.

Stanley J. Brodsky

2014-10-01T23:59:59.000Z

493

Effective Field Theory Approach to Parton-Hadron Conversion in High Energy QCD Processes  

E-Print Network [OSTI]

A QCD based effective action is constructed to describe the dynamics of confinement and symmetry breaking in the process of parton-hadron conversion. The deconfined quark and gluon degrees of freedom of the perturbative QCD vacuum are coupled to color singlet collective fields representing the non-perturbative vacuum with broken scale and chiral symmetry. The effective action recovers QCD with its scale and chiral symmetry properties at short space-time distances, but yields at large distances (r > 1 fm) to the formation of symmetry breaking gluon and quark condensates. The approach is applied to the evolution of a fragmenting $q\\bar q$ pair with its generated gluon distribution, starting from a large hard scale $Q^2$. The modification of the gluon distribution arising from the coupling to the non-perturbative collective field results eventually in a complete condensation of gluons. Color flux tube configurations of the gluons in between the $q\\bar q$ pair are obtained as solutions of the equations of motion. With reasonable parameter choice, the associated energy per unit length (string tension) comes out $\\simeq 1$ GeV/fm, consistent with common estimates.

K. Geiger

1994-09-14T23:59:59.000Z

494

Thermodynamics of Two Flavor QCD to Sixth Order in Quark Chemical Potential  

E-Print Network [OSTI]

We present results of a simulation of 2-flavor QCD on a 4x16^3 lattice using p4-improved staggered fermions with bare quark mass m/T=0.4. Derivatives of the thermodynamic grand canonical partition function Z(V,T,mu_u,mu_d) with respect to chemical potentials mu_(u,d) for different quark flavors are calculated up to sixth order, enabling estimates of the pressure and the quark number density as well as the chiral condensate and various susceptibilities as functions of mu_q = (mu_u + mu_d)/2 via Taylor series expansion. Furthermore, we analyze baryon as well as isospin fluctuations and discuss the relation between the radius of convergence of the Taylor series and the chiral critical point in the QCD phase diagram. We argue that bulk thermodynamic observables do not, at present, provide direct evidence for the existence of a chiral critical point in the QCD phase diagram. Results are compared to high temperature perturbation theory as well as a hadron resonance gas model.

C. R. Allton; M. Doering; S. Ejiri; S. J. Hands; O. Kaczmarek; F. Karsch; E. Laermann; K. Redlich

2005-01-30T23:59:59.000Z

495

Bag model of hadrons, dual QCD thermodynamics and Quark-Gluon Plasma  

E-Print Network [OSTI]

Using the grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of the dual QCD has been presented in terms of the bag model of hadrons and analyzed for the quark-gluon plasma phase of hadronic matter. The dual QCD bag construction has been shown to lead to the radial pressure on the bag surface in terms of the vector glueball masses of the magnetically condensed QCD vacuum. Constructing the grand canonical partition function to deal with the quark-gluon plasma phase of the non-strange hadrons, the energy density and the plasma pressure have been derived and used to understand the dynamics of the associated phase transition. The critical temperature for QGP-hadron phase transition has been derived and numerically estimated by using various thermodynamic considerations. A comparison of the values of the critical temperatures for QGP-hadron phase transition with those obtained for the deconfinement-phase transition, has been shown to lead to the relaxation ...

Chandola, H C; Dehnen, H

2015-01-01T23:59:59.000Z

496

Quantum Computing via The Bethe Ansatz  

E-Print Network [OSTI]

We recognize quantum circuit model of computation as factorisable scattering model and propose that a quantum computer is associated with a quantum many-body system solved by the Bethe ansatz. As an typical example to support our perspectives on quantum computation, we study quantum computing in one-dimensional nonrelativistic system with delta-function interaction, where the two-body scattering matrix satisfies the factorisation equation (the quantum Yang--Baxter equation) and acts as a parametric two-body quantum gate. We conclude by comparing quantum computing via the factorisable scattering with topological quantum computing.

Yong Zhang

2011-06-20T23:59:59.000Z

497

QCD and nuclear physics. How to explain the coincidence between the radius of the strong interaction of nucleons and the characteristic scale of neutron-neutron electrostatic interaction?  

E-Print Network [OSTI]

An attempt is made to interpret, in the framework of QCD, the coincidence of two observable scales which characterize the interaction between neutrons.

Godizov, A A

2014-01-01T23:59:59.000Z

498

Computational equivalence between quantum Turing machines  

E-Print Network [OSTI]

Computational equivalence between quantum Turing machines and quantum circuit families Christian Westergaard 21st November 2005 Contents 1 The quantum Turing machine model 5 1.1 Basics of quantum Turing machines . . . . . . . . . . . . . . . . . . . 5 1.2 Projections on the quantum state space

Møller, Jesper Michael

499

On Quantum Capacity and its Bound  

E-Print Network [OSTI]

The quantum capacity of a pure quantum channel and that of classical-quantum-classical channel are discussed in detail based on the fully quantum mechanical mutual entropy. It is proved that the quantum capacity generalizes the so-called Holevo bound.

Masanori Ohya; Igor V. Volovich

2004-06-29T23:59:59.000Z

500

Hybrid quantum-classical models as constrained quantum systems  

E-Print Network [OSTI]

Constrained Hamiltonian description of the classical limit is utilized in order to derive consistent dynamical equations for hybrid quantum-classical systems. Starting with a compound quantum system in the Hamiltonian formulation conditions for classical behavior are imposed on one of its subsystems and the corresponding hybrid dynamical equations are derived. The presented formalism suggests that the hybrid systems have properties that are not exhausted by those of quantum and classical systems.

M. Radonjic; S. Prvanovic; N. Buric

2012-06-07T23:59:59.000Z