Lincoln, Don
2016-07-12
The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilabâs Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.
Lattice Quantum Chromodynamics
U.S. Department of Energy (DOE) all webpages (Extended Search)
Lattice Quantum Chromodynamics Lattice Quantum Chromodynamics QCD-BU.jpg Key Challenges: Although the QCD theory has been extensively tested at at high energies, at low energies or...
Experimental results on QCD (Quantum Chromodynamics) from e/sup +/e/sup -/ annihilation
de Boer, W.
1987-09-01
A review is given on QCD results from studying e/sup +/e/sup -/ annihilation with the PEP and PETRA storage rings with special emphasis on jet physics and the determination of the strong coupling constant ..cap alpha../sub s/. 92 refs., 28 figs., 3 tabs.
Resonant ?+???+?0 amplitude from Quantum Chromodynamics
Briceo, Ral A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.
2015-12-08
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude for $\\pi\\pi \\to \\pi\\gamma^\\star$, as a function of the energy of the $\\pi\\pi$ pair and the virtuality of the photon, in the kinematic regime where $\\pi\\pi$ couples strongly to the unstable $\\rho$ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to $m_\\pi \\approx 400$ MeV. As a result, we obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analyticallymorecontinue to the $\\rho$ pole and identify from its residue the $\\rho \\to \\pi\\gamma^\\star$ form-factor.less
Novel nuclear phenomena in quantum chromodynamics
Brodsky, S.J.
1987-08-01
Many of the key issues in understanding quantum chromodynamics involve processes in nuclear targets at intermediate energies. A range of hadronic and nuclear phenomena-exclusive processes, color transparency, hidden color degrees of freedom in nuclei, reduced nuclear amplitudes, jet coalescence, formation zone effects, hadron helicity selection rules, spin correlations, higher twist effects, and nuclear diffraction were discussed as tools for probing hadron structure and the propagation of quark and gluon jets in nuclei. Several areas were also reviewed where there has been significant theoretical progress determining the form of hadron and nuclear wave functions, including QCD sum rules, lattice gauge theory, and discretized light-cone quantization. A possible interpretation was also discussed of the large spin correlation A/sub NN/ in proton-proton scattering, and how relate this effect to an energy and angular dependence of color transparency in nuclei. 76 refs., 24 figs.
Double logarithmic asymptotic behavior in quantum chromodynamics
Kirschner, R.
1981-08-01
The double logarithmic contributions to the quark-(anti)quark scattering and annihilation amplitudes are summed to all orders in quantum chromodynamics. The results are a generalization of the calculations of Gorshkov et al. in the case of quantum electrodynamics.
Resonances in Coupled ?K??K Scattering from Quantum Chromodynamics
Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.; Wilson, David J.
2014-10-01
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 ?K, ?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.
Exclusive processes in quantum chromodynamics
Brodsky, S.J.; Lepage, G.P.
1981-06-01
Large momentum transfer exclusive processes and the short distance structure of hadronic wave functions can be systematically analyzed within the context of perturbative QCD. Predictions for meson form factors, two-photon processes ..gamma gamma.. ..-->.. M anti M, hadronic decays of heavy quark systems, and a number of other related QCD phenomena are reviewed.
Nuclear Forces from Lattice Quantum Chromodynamics Martin J....
U.S. Department of Energy (DOE) all webpages (Extended Search)
Forces from Lattice Quantum Chromodynamics Martin J. Savage Institute for Nuclear Theory Large Scale Computing and Storage Requirements for Nuclear Physics (NP): Target 2017 April ...
Resonances in Coupled πK-ηK Scattering from Quantum Chromodynamics
Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.; Wilson, David J.
2014-10-01
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 πK, ηK 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.
Quantum Chromodynamics and Nuclear Physics at Extreme Energy Density
Mueller, B.; Bass, S.A.; Chandrasekharan, S.; Mehen, T.; Springer, R.P.
2005-11-07
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.
Heavy-quark physics in quantum chromodynamics
Brodsky, S.J.
1991-04-01
Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as {Upsilon} {yields} p{bar p} and B {yields} {pi}{pi}, and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x{sub F} and give anomalous contributions to the quark structure functions of ordinary hadrons at large x{sub bj}. I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/{psi} and {Upsilon} production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x{sub F}, and the coalescence of heavy quarks with co-moving spectators at low x{sub F}.
Resonant π+γ→π+π0 amplitude from Quantum Chromodynamics
Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.
2015-12-08
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude formore » $$\\pi\\pi \\to \\pi\\gamma^\\star$$, as a function of the energy of the $$\\pi\\pi$$ pair and the virtuality of the photon, in the kinematic regime where $$\\pi\\pi$$ couples strongly to the unstable $$\\rho$$ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to $$m_\\pi \\approx 400$$ MeV. As a result, we obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the $$\\rho$$ pole and identify from its residue the $$\\rho \\to \\pi\\gamma^\\star$$ form-factor.« less
QCDOC -Quantum Chromodynamics on a Chip at BNL | U.S. DOE Office...
QCDOC -Quantum Chromodynamics on a Chip at BNL Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Applications of Nuclear Science Applications ...
The application of light-cone quantization to quantum chromodynamics in one-plus-one dimensions
Hornbostel, K.J.
1988-12-01
Formal and computational aspects of light cone quantization are studied by application to quantum chromodynamics (QCD) in one spatial plus one temporal dimension. This quantization scheme, which has been extensively applied to perturbative calculations, is shown to provide an intuitively appealing and numerically tractable approach to non-perturbative computations as well. In the initial section, a light-cone quantization procedure is developed which incorporates fields on the boundaries. This allows for the consistent treatment of massless fermions and the construction of explicitly conserved momentum and charge operators. The next section, which comprises the majority of this work, focuses on the numerical solution of the light-cone Schrodinger equation for bound states. The state space is constructed and the Hamiltonian is evaluated and diagonalized by computer for arbitrary number of colors, baryon number and coupling constant strength. As a result, the full spectrum of mesons and baryons and their associated wavefunctions are determined. These results are compared with those which exist from other approaches to test the reliability of the method. The program also provides a preliminary test for the feasibility of, and an opportunity to develop approximation schemes for, an attack on three-plus-one dimensional QCD. Finally, analytic results are presented which include a discussion of integral equations for wavefunctions and their endpoint behavior. Solutions for hadronic masses and wavefunctions in the limits of both large and small quark mass are discussed. 49 refs., 32 figs., 10 tabs.
Resonances in Coupled $\pi K\text{-}\eta K$ Scattering from Quantum Chromodynamics
Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.; Wilson, David J.
2014-10-01
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 πK, ηK 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.
New parton distribution functions from a global analysis of quantum chromodynamics
Dulat, Sayipjamal; Hou, Tie -Jiun; Gao, Jun; Guzzi, Marco; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C. -P.; Huston, Joey
2016-02-16
Here, we present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged lepton rapidity asymmetry data, as well as the use of more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. Formore » completeness, we also present the CT14 PDFs determined at the leading order (LO) and the next-to-leading order (NLO) in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various αs values and additional sets in general-mass variable flavor number (GM-VFN) schemes, to deal with heavy partons, with up to 3, 4, and 6 active flavors.« less
High Energy Physics Division, ANL Lattice QCD
U.S. Department of Energy (DOE) all webpages (Extended Search)
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.
Light Nuclei and HyperNuclei from Quantum Chromodynamics in the Limit of SU(3) Flavor Symmetry
Beane, S R; Cohen, S D; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J
2013-02-01
The binding energies of a range of nuclei and hypernuclei with atomic number A <= 4 and strangeness |s| <= 2, including the deuteron, di-neutron, H-dibaryon, {sup 3}He, {sub {Lambda}}{sup 3}He, {sub {Lambda}}{sup 4}He, and {sub {Lambda}{Lambda}}{sup 4}He, are calculated in the limit of flavor-SU(3) symmetry at the physical strange quark mass with quantum chromodynamics (without electromagnetic interactions). The nuclear states are extracted from Lattice QCD calculations performed with n{sub f}=3 dynamical light quarks using an isotropic clover discretization of the quark-action in three lattice volumes of spatial extent L ~ 3.4 fm, 4.5 fm and 6.7 fm, and with a single lattice spacing b ~ 0.145 fm.
Two-photon exclusive processes in quantum chromodynamics
Brodsky, S.J.
1986-07-01
QCD predictions for ..gamma gamma.. annihilation into single mesons, meson pairs, and baryon pairs are reviewed. Two-photon exclusive processes provide the most sensitive and practical measure of the distribution amplitudes, and thus a critical confrontation between QCD and experiment. Both the angular distribution and virtual photon mass dependence of these amplitudes are sensitive to the shapes of the phi (chi, Q). Novel effects involving the production of qq anti q anti q states at threshold are also discussed, and a new method is presented for systematically incorporating higher-order QCD corrections in ..gamma gamma.. reactions.
Mueller, B.
1993-05-15
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.
QCDOC -Quantum Chromodynamics on a Chip at BNL | U.S. DOE Office of Science
(SC) QCDOC -Quantum Chromodynamics on a Chip at BNL Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Applications of Nuclear Science Applications of Nuclear Science Archives Small Business Innovation Research / Small Business Technology Transfer Funding Opportunities Nuclear Science Advisory Committee (NSAC) Community Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26/Germantown Building 1000 Independence Ave., SW Washington,
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
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 mπ ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. 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 itsmore » dominant structure. Similarly a shell-model-like moment is found for the triton, μ3H ~ μp. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.« less
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S.? R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H.? W.; Orginos, K.; Parreo, A.; Savage, M.? J.; Tiburzi, B.? C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and ^{3}He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m_{?} ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of ^{3}He 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, ?_{3H} ~ ?_{p}. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and ^{3}He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m_{π} ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of ^{3}He 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, μ_{3H} ~ μ_{p}. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.
Murray Gell-Mann, the Eightfold Way, Quarks, and Quantum Chromodynamics
U.S. Department of Energy (DOE) all webpages (Extended Search)
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,
Hadronic Resonances from Lattice QCD
Lichtl, Adam C.; Bulava, John; Morningstar, Colin; Edwards, Robert; Mathur, Nilmani; Richards, David; Fleming, George; Juge, K. Jimmy; Wallace, Stephen J.
2007-10-26
The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.
Hadronic Resonances from Lattice QCD
John Bulava; Robert Edwards; George Fleming; K. Jimmy Juge; Adam C. Lichtl; Nilmani Mathur; Colin Morningstar; David Richards; Stephen J. Wallace
2007-06-16
The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.
Color transparency and the structure of the proton in quantum chromodynamics
Brodsky, S.J.
1989-06-01
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.
Resonant ${?}^{+}??{?}^{+}{?}^{0}$ amplitude from Quantum Chromodynamics
Briceo, Ral A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.
2015-12-08
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude for $\\pi\\pi \\to \\pi\\gamma^\\star$, as a function of the energy of the $\\pi\\pi$ pair and the virtuality of the photon, in the kinematic regime where $\\pi\\pi$ couples strongly to the unstable $\\rho$ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to $m_\\pi \\approx 400$ MeV. As a result, we obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the $\\rho$ pole and identify from its residue the $\\rho \\to \\pi\\gamma^\\star$ form-factor.
Hyperon-Nucleon Interactions and the Composition of Dense Nuclear Matter from Quantum Chromodynamics
Beane, S R; Cohen, S D; Detmold, W; Lin, H -W; Luu, T C; Orginos, K; Parreno, A; Savage, M J
2012-10-01
The low-energy neutron-{Sigma}{sup -} interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from a numerical evaluation of the QCD path integral using the technique of Lattice QCD. Our calculations, performed at a pion mass of m{sub pi} ~ 389 MeV in two large lattice volumes, and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The interactions determined from QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties, and strengthen theoretical arguments that the strange quark is a crucial component of dense nuclear matter.
Hyperon-Nucleon Interactions and the Composition of Dense Matter from Quantum Chromodynamics
Konstantinos Orginos, Silas Beane, Emmanuel Chang, Saul Cohen, Huey-Wen Lin, Tom Luu, Assumpta Parreno, Martin Savage, Andre Walker-Loud, William Detmold
2012-10-01
The low-energy n{Sigma}{sup -} interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase-shifts for this system are determined from a numerical evaluation of the QCD path integral using the technique of Lattice QCD. Our results, performed at a pion mass of m{sub {pi}} ~ 389 MeV in two large lattice volumes, and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The calculated interactions indicate that the strange quark plays an important role in dense matter.
Brodsky, S.J.
1983-11-01
A number of novel features of QCD are reviewed, including the consequences of formation zone and color transparency phenomena in hadronic collisions, the use of automatic scale setting for perturbative predictions, null-zone phenomena as a fundamental test of gauge theory, and the relationship of intrinsic heavy colored particle Fock state components to new particle production. We conclude with a review of the applications of QCD to nuclear multiquark systems. 74 references.
Resonant ${\pi}^{+}\gamma \to {\pi}^{+}{\pi}^{0}$ amplitude from Quantum Chromodynamics
Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.
2015-12-08
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude for $\\pi\\pi \\to \\pi\\gamma^\\star$, as a function of the energy of the $\\pi\\pi$ pair and the virtuality of the photon, in the kinematic regime where $\\pi\\pi$ couples strongly to the unstable $\\rho$ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to $m_\\pi \\approx 400$ MeV. As a result, we obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the $\\rho$ pole and identify from its residue the $\\rho \\to \\pi\\gamma^\\star$ form-factor.
Deta, U. A.; Suparmi,; Cari,; Husein, A. S.; Yuliani, H.; Khaled, I. K. A.; Luqman, H.; Supriyanto
2014-09-30
The Energy Spectra and Wave Function of Schrodinger equation in D-Dimensions for trigonometric Rosen-Morse potential were investigated analytically using Nikiforov-Uvarov method. This potential captures the essential traits of the quark-gluon dynamics of Quantum Chromodynamics. The approximate energy spectra are given in the close form and the corresponding approximate wave function for arbitrary l-state (l ? 0) in D-dimensions are formulated in the form of differential polynomials. The wave function of this potential unnormalizable for general case. The wave function of this potential unnormalizable for general case. The existence of extra dimensions (centrifugal factor) and this potential increase the energy spectra of system.
Infrared behavior of real-time quark dispersion relations in hot QCD
Bouakaz, K.; Abada, A.
2012-06-27
We determine the analytic contributions to the complex self energy of slow-moving quarks in the context of hard-thermal-loop summed perturbation of massless quantum chromodynamics (QCD) at high temperature. The calculation is done using the real time formalism.
Sekhar Chivukula
2016-07-12
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 presentÂ at the classical level. Â Quantum Chromodynamics (QCD),Â the modern theoryÂ of the strong interactions, exemplify each ofÂ these possibilities.Â The interplayÂ of these effects determine theÂ spectrum of particles that we observeÂ and, ultimately, account forÂ 99% of the mass of ordinary matter.Â
Color force saturation in nuclear chromodynamics
Sivers, D.
1985-01-01
A simple representation of the Q anti QQ anti Q Green's Function in the strong coupling quenched approximation to lattice QCD is used to illustrate the nature of color force saturation in chromodynamics. The example shows that configuration mixing allows a binding energy of a few MeV in a Q anti QQ anti Q ''molecule'' formed from mesons with mass 1 GeV. In lattice QCD, configuration mixing can be calculated on the same footing with glueball exchange effects by measuring the appropriate operators in a Monte Carlo simulation. 3 refs., 5 figs.
Uncertainty quantification in lattice QCD calculations for nuclear physics
Beane, Silas R.; Detmold, William; Orginos, Kostas; Savage, Martin J.
2015-02-05
The numerical technique of Lattice QCD holds the promise of connecting the nuclear forces, nuclei, the spectrum and structure of hadrons, and the properties of matter under extreme conditions with the underlying theory of the strong interactions, quantum chromodynamics. A distinguishing, and thus far unique, feature of this formulation is that all of the associated uncertainties, both statistical and systematic can, in principle, be systematically reduced to any desired precision with sufficient computational and human resources. As a result, we review the sources of uncertainty inherent in Lattice QCD calculations for nuclear physics, and discuss how each is quantified in current efforts.
Quarkonium states in an anisotropic QCD plasma
Dumitru, Adrian; Guo Yun; Mocsy, Agnes; Strickland, Michael
2009-03-01
We consider quarkonium in a hot quantum chromodynamics (QCD) plasma which, due to expansion and nonzero viscosity, exhibits a local anisotropy in momentum space. At short distances the heavy-quark potential is known at tree level from the hard-thermal loop resummed gluon propagator in anisotropic perturbative QCD. The potential at long distances is modeled as a QCD string which is screened at the same scale as the Coulomb field. At asymptotic separation the potential energy is nonzero and inversely proportional to the temperature. We obtain numerical solutions of the three-dimensional Schroedinger equation for this potential. We find that quarkonium binding is stronger at nonvanishing viscosity and expansion rate, and that the anisotropy leads to polarization of the P-wave states.
Nuclear reactions from lattice QCD
Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.
2015-01-13
In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.
Nuclear reactions from lattice QCD
Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.
2015-01-13
In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculationsmore » of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.« less
QCD and Hadron Physics (Conference) | SciTech Connect
Office of Scientific and Technical Information (OSTI)
Language: English Subject: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; QUANTUM CHROMODYNAMICS; HADRONS; MEETINGS; RECOMMENDATIONS; EXPERIMENT PLANNING; PARTICLE STRUCTURE ...
Deur, Alexandre; Brodsky, Stanley J.; de Téramond, Guy F.
2016-05-09
Here, we review present knowledge onmore » $$\\alpha_{s}$$, the Quantum Chromodynamics (QCD) running coupling. The dependence of $$\\alpha_s(Q^2)$$ on momentum transfer $Q$ encodes the underlying dynamics of hadron physics --from color confinement in the infrared domain to asymptotic freedom at short distances. We will survey our present theoretical and empirical knowledge of $$\\alpha_s(Q^2)$$, including constraints at high $Q^2$ predicted by perturbative QCD, and constraints at small $Q^2$ based on models of nonperturbative dynamics. In the first, introductory, part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain. In the second, more technical, part of the review, we discuss $$\\alpha_s(Q^2)$$ in the high momentum transfer domain of QCD. We review how $$\\alpha_s$$ is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as `` Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization scale ambiguity. We also report recent important experimental measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the ``Principle of Maximum Conformality" which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of the gauge and renormalization scheme. In last part of the review, we discuss $$\\alpha_s(Q^2)$$ in the low momentum transfer domain, where there has been no consensus on how to define $$\\alpha_s(Q^2)$$ or its analytic behavior. We will discuss the various approaches used for low energy calculations. Among them, we will discuss the light-front holographic approach to QCD in the strongly coupled
Nuclear chromodynamics is not the colorization of nuclear physics
Sivers, D.
1988-07-19
The successful description of nuclei in terms of nucleons, deltas and mesons provides an enormous challenge to QCD. It compels us to pursue our theoretical understanding of chromodynamics into the realm of multiple color singlets in order to examine the concept of color saturation. To pursue this theme, we examine the idea of nuclear transparency in the light of models for confinement and describe the formulation of lattice simulations sensitive to exchange forces. 22 refs., 7 figs.
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Huston, Joey [Co-Spokesperson; Ownes, Joseph [Co-Spokesperson
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.
Nonrelativistic QCD factorization and the velocity dependence...
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CONFIGURATION; FACTORIZATION; MATRIX ELEMENTS; QUANTUM CHROMODYNAMICS; QUARKONIUM; SINGULARITY; T QUARKS; VELOCITY Word Cloud More Like This Full Text Journal Articles DOI: ...
Workshop on nuclear chromodynamics: Quarks and gluons in particles and nuclei
Brodsky, S.; Moniz, Ernest
1985-01-01
The assertion that quantum chromodynamics (QCD) is the correct theory describing strong interaction phenomena has, largely by repetition, become rather non-controversial. It is likely even true. However, whether or not it is correct in detail, the experimentally supported realization that colored quarks and gluons are the elementary degrees of freedom, that asymptotic freedom makes short distance phenomena rather ''simple'' to understand, and that color is confined on the hadronic length scale of -- 1 fm has led to a profound change in the character of our attempts to understand the structure and interactions of both hadrons and nuclei. Many of the most important issued in particle physics and in nuclear physics are now seen to be intimately connected. An understanding of the validity and limits of effective theories based upon hadron degrees of freedom, so phenomenologically successful in describing a host of low energy phenomena, is coming into focus. The existence of new forms of matter grounded in the hidden color degree of freedom is predicted. These considerations form the subject of nuclear chromodynamics (NCD). The subject is far from mature and is developing rapidly.
Hamiltonian Light-front Field Theory Within an AdS/QCD Basis
Vary, J.P.; Honkanen, H.; Li, Jun; Maris, P.; Brodsky, S.J.; Harindranath, A.; de Teramond, G.F.; Sternberg, P.; Ng, E.G.; Yang, C.; /LBL, Berkeley
2009-12-16
Non-perturbative Hamiltonian light-front quantum field theory presents opportunities and challenges that bridge particle physics and nuclear physics. Fundamental theories, such as Quantum Chromodynamics (QCD) and Quantum Electrodynamics (QED) offer the promise of great predictive power spanning phenomena on all scales from the microscopic to cosmic scales, but new tools that do not rely exclusively on perturbation theory are required to make connection from one scale to the next. We outline recent theoretical and computational progress to build these bridges and provide illustrative results for nuclear structure and quantum field theory. As our framework we choose light-front gauge and a basis function representation with two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall AdS/QCD model obtained from light-front holography.
Light-cone quantization and QCD phenomenology
Brodsky, S.J.; Robertson, D.G.
1995-12-31
In principle, quantum chromodynamics provides a fundamental description of hadronic and nuclear structure and dynamics in terms of their elementary quark and gluon degrees of freedom. In practice, the direct application of QCD to reactions involving the structure of hadrons is extremely complex because of the interplay of nonperturbative effects such as color confinement and multi-quark coherence. A crucial tool in analyzing such phenomena is the use of relativistic light-cone quantum mechanics and Fock state methods to provide tractable and consistent treatments of relativistic many-body systems. In this article we present an overview of this formalism applied to QCD, focusing in particular on applications to the final states in deep inelastic lepton scattering that will be relevant for the proposed European Laboratory for Electrons (ELFE), HERMES, HERA, SLAC, and CEBAF. We begin with a brief introduction to light-cone field theory, stressing how it many allow the derivation of a constituent picture, analogous to the constituent quark model, from QCD. We then discuss several applications of the light-cone Fock state formalism to QCD phenomenology. The Fock state representation includes all quantum fluctuations of the hadron wavefunction, including far off-shell configurations such as intrinsic charm and, in the case of nuclei, hidden color. In some applications, such as exclusive processes at large momentum transfer, one can make first-principle predictions using factorization theorems which separate the hard perturbative dynamics from the nonpertubative physics associated with hadron binding. The Fock state components of the hadron with small transverse size, which dominate hard exclusive reactions, have small color dipole moments and thus diminished hadronic interactions. Thus QCD predicts minimal absorptive corrections, i.e., color transparency for quasi-elastic exclusive reactions in nuclear targets at large momentum transfer.
Wilson Dslash Kernel From Lattice QCD Optimization
Joo, Balint; Smelyanskiy, Mikhail; Kalamkar, Dhiraj D.; Vaidyanathan, Karthikeyan
2015-07-01
Lattice Quantum Chromodynamics (LQCD) is a numerical technique used for calculations in Theoretical Nuclear and High Energy Physics. LQCD is traditionally one of the first applications ported to many new high performance computing architectures and indeed LQCD practitioners have been known to design and build custom LQCD computers. Lattice QCD kernels are frequently used as benchmarks (e.g. 168.wupwise in the SPEC suite) and are generally well understood, and as such are ideal to illustrate several optimization techniques. In this chapter we will detail our work in optimizing the Wilson-Dslash kernels for Intel Xeon Phi, however, as we will show the technique gives excellent performance on regular Xeon Architecture as well.
QCD, Tevatron results and LHC prospects
Elvira, V.Daniel; /Fermilab
2008-08-01
We present a summary of the most recent measurements relevant to Quantum Chromodynamics (QCD) delivered by the D0 and CDF Tevatron experiments by May 2008. CDF and D0 are moving toward precision measurements of QCD based on data samples in excess of 1 fb-1. The inclusive jet cross sections have been extended to forward rapidity regions and measured with unprecedented precision following improvements in the jet energy calibration. Results on dijet mass distributions, bbbar dijet production using tracker based triggers, underlying event in dijet and Drell-Yan samples, inclusive photon and diphoton cross sections complete the list of measurements included in this paper. Good agreement with pQCD within errors is observed for jet production measurements. An improved and consistent theoretical description is needed for photon+jets processes. Collisions at the LHC are scheduled for early fall 2008, opening an era of discoveries at the new energy frontier, 5-7 times higher than that of the Tevatron.
Yuri Kovchegov
2012-05-31
The project significantly advanced our understanding of the theory of strong interactions known as quantum chromodynamics (QCD) in high energy collisions of elementary particles and nuclei. QCD is one of the four fundamental forces of nature, but is understood quite poorly due to the complexity of strong interactions. This project advanced our understanding of QCD in the very high energy collisions of protons and nuclei, where densities of quarks and gluons inside the colliding particles are so high (due to high energy) that complicated nonlinear interactions between quarks and gluons become important. This regime is known as gluon (or parton) saturation. The result of the project is a significant improvement of our understanding of the physics of gluon saturation: important (running coupling) corrections to the existing description of the process (the so-called Balitsky-Kovchegov equation) have been calculated, placing the BK equation in good agreement with the experimental data on deep inelastic scattering (DIS), a process where an electron is collided with the proton to probe the proton's internal structure. Corresponding cross section for quark and gluon production in DIS and nuclear collisions have been calculated and corrected correspondingly, resulting in new and interesting predictions for the physics to be probed in heavy ion collisions at the Large Hadron Collider (LHC). The dense gluon systems play an important role in collisions of ultrarelativistic large nuclei, which are performed in order to create a plasma of quarks and gluons (QGP). An important question in the field is how exactly this QGP is produced in a collision of two heavy ions. The conclusion of this project is that QGP production happens due to strong coupling effects between quarks and gluons. This made theoretical description of QGP production only possible using the methods emerging from string theory. Using these methods QGP production was well understood as a result of this project
1998-10-16
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.
Multi-meson systems in lattice QCD / Many-body QCD
Detmold, William
2013-08-31
Nuclear physics entails the study of the properties and interactions of hadrons, such as the proton and neutron, and atomic nuclei and it is central to our understanding of our world at the smallest scales. The underlying basis for nuclear physics is provided by the Standard Model of particle physics which describes how matter interacts through the strong, electromagnetic and weak (electroweak) forces. This theory was developed in the 1970s and provides an extremely successful description of our world at the most fundamental level to which it has been probed. The Standard Model has been, and continues to be, subject to stringent tests at particle accelerators around the world, so far passing without blemish. However, at the relatively low energies that are relevant for nuclear physics, calculations involving the strong interaction, governed by the equations of Quantum Chromodynamics (QCD), are enormously challenging, and to date, the only systematic way to perform them is numerically, using a framework known as lattice QCD (LQCD). In this approach, one discretizes space-time and numerically solves the equations of QCD on a space-time lattice; for realistic calculations, this requires highly optimized algorithms and cutting-edge high performance computing (HPC) resources. Progress over the project period is discussed in detail in the following subsections
The QCD/SM working group: A Summary report
Alekhin, S.; Balazs, C.; Ball, R.; Binoth, T.; Boos, E.; Botje, M.; Cacciari, M.; Catani, S.; Del Duca, V.; Dobbs, M.; Ellis, S.D.; Field, R.; deFlorian, D.; Forte, S.; Gardi, E.; Gehrmann, T.; Gehrmann-De Riddler, A.; Giele, W.; Glover, E.W.N.; Grazzini, M.; Guillet, J.-Ph.; HeinRich, G.; Huston, J.; Hinchliffe, I.; Llyin, V.; Kanzaki, J.; Kato, K.; Kersevan, B.; Kidonakis, N.; Kulesza, A.; Kurihara, Y.; Laenen, E.; Lassila-Perini, K.; Lonnblad, L.; Magnea, L.; Mangano, M.; Mazumudar, K.; Moch, S.; Mrenna, S.; Nadolsky, P.; Nason, P.; Olness, F.; Paige, F.; Puljak, I.; Pumplin, J.; Richter-Was, E.; Salam, G.; Scalise, R.; Seymour, M.; Sjostrand, T.; Sterman, G.; Monnesmann, M.; Tournefier, E.; Vogelsang, W.; Vogt, A.; Vogt, R.; Webber, B.; Yuan, C.-P.; Zeppenfeld, D.
2002-04-01
This report documents the results obtained by the Working Group on Quantum Chromodynamics and the Standard Model for the Workshop ''Physics at TeV Colliders,'' Les Houches, France, 26 May - 6 June 2003. After a Monte Guide description, the first contributions report on progress in describing multiple interactions, important for the LHC, and underlying events. An announcement of a Monte Carlo database, under construction, is then followed by a number of contributions improving parton shower descriptions. Subsequently, a large number of contributions address resummations in various forms, after which follow studies of QCD effects in pion pair, top quark pair and photon pair plus jet production. After a study of electroweak corrections to hadronic precision observables, the report ends by presenting recent progress in methods to compute finite order corrections at one-loop with many legs, and at two-loop.
Lattice Quantum Chromodynamics (SPI, mapping, site ordering,...
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Resource Type: Technical Report Research Org: Argonne National Laboratory (ANL) Sponsoring Org: SC OFFICE OF BASIC ENERGY SCIENCES Country of Publication: United States Language: ...
Lattice Quantum Chromodynamics (SPI, mapping, site ordering,...
Office of Scientific and Technical Information (OSTI)
LCF Publication Date: 2013-05-14 OSTI Identifier: 1079769 Report Number(s): ANLALCFESP-1311 DOE Contract Number: DE-AC02-06CH11357 Resource Type: Technical Report Research...
Two-loop ultrasoft running of the O(v{sup 2}) QCD quark potentials...
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Subject: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANNIHILATION; B QUARKS; C QUARKS; FEYNMAN DIAGRAM; PAIR PRODUCTION; POTENTIALS; QUANTUM CHROMODYNAMICS; T QUARKS Word Cloud ...
Hadronic resonances above the QCD phase transition
Blaschke, D.
2005-06-14
We describe matter formed in ultrarelativistic heavy ion collisions within a generalized Hagedorn resonance gas model where hadrons have a vanishing width below the Hagedorn temperature TH and a Hagedorn spectrum-like width above TH. Such an approach not only eliminates the divergence of the thermodynamic functions above TH, but it is able to successfully describe the lattice quantum chromodynamics (QCD) data on the energy density. It also allows to explain the absence of heavy resonance contributions in the fit of the experimentally measured particle ratios at SPS and RHIC energies. We present an application of the approach to the description of the NA50 experiment which suggests that the anomalous suppression of J/{psi} production may be explained by the increase of the effective number of degrees of freedom at the Hagedorn temperature. We estimate the shear viscosity of the generalized Hagedorn resonance gas model and find remarkable agreement with the perfect liquid bound {eta}/s {>=} 1/(4{pi})
U.S. Department of Energy (DOE) all 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 Lattice QCD at Los Alamos lattice Figure: (Above) The behavior of (energy - 3 x pressure) of QCD as a function of the temperature calculated by the HotQCD collaboration. The equation of state of QCD is extracted from this data and used in the analysis of experimental data produced in the collisions of relativistic
Chromodynamic fluctuations in quark-gluon plasma
Mrowczynski, Stanislaw
2008-05-15
Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary, and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.
Importance of proper renormalization scale-setting for QCD testing at colliders
Wu, Xing-Gang; Wang, Sheng-Quan; Brodsky, Stanley J.
2015-12-22
A primary problem affecting perturbative quantum chromodynamic (pQCD) analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality (PMC) eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set order-by-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived from the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant αs to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the NC → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the “increasing-decreasing” behavior observed by the D0 collaboration for increasing tt invariant mass. At lower energies
Importance of proper renormalization scale-setting for QCD testing at colliders
Wu, Xing -Gang; Wang, Sheng -Quan; Brodsky, Stanley J.
2015-12-22
A primary problem affecting perturbative quantum chromodynamic (pQCD) analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality (PMC) eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set order-by-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived frommore » the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant αs to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the NC → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the “increasing-decreasing” behavior observed by the D0 collaboration for increasing tt¯ invariant mass. At lower
Importance of proper renormalization scale-setting for QCD testing at colliders
Wu, Xing -Gang; Wang, Sheng -Quan; Brodsky, Stanley J.
2015-12-22
A primary problem affecting perturbative quantum chromodynamic (pQCD) analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality (PMC) eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set order-by-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived from the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant αs to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the N_{C} → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the “increasing-decreasing” behavior observed by the D0 collaboration for increasing tt¯ invariant mass. At lower
The QCD/SM working group: Summary report
W. Giele et al.
2004-01-12
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
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QPX for Lattice QCD James C. Osborn Argonne Leadership Computing Facility Mira Boot Camp ... Quantum Chromodynamics (QCD) fundamental theory of strong nuclear force part of ...
Color Glass Condensate in Schwinger-Keldysh QCD (Journal Article...
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-- Highlights: *Application of the Schwinger-Keldysh formalism to many-body QCD. *Clean separation of classical and quantum degrees of freedom. *Identification of the correct ...
Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins
2011-08-12
I review a number of topics where conventional wisdom in hadron physics has been challenged. For example, hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation. Such 'direct' processes can explain the 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. Initial-state and final-state interactions of the struck quark, the soft-gluon rescattering associated with its Wilson line, lead to Bjorken-scaling single-spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as nuclear shadowing and antishadowing. The Gribov-Glauber theory predicts that antishadowing of nuclear structure functions is not universal, but instead depends on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence measured in deep-inelastic neutrino scattering. Since shadowing and antishadowing arise from the physics of leading-twist diffractive deep inelastic scattering, one cannot attribute such phenomena to the structure of the nucleus itself. It is thus important to distinguish 'static' structure functions, the probability distributions computed from the square of the target light-front wavefunctions, versus 'dynamical' structure functions which include the effects of the final-state rescattering of the struck quark. The importance of the J = 0 photon-quark QCD contact interaction in deeply virtual Compton scattering is also emphasized. The scheme-independent BLM method for setting the renormalization scale is discussed. Eliminating the renormalization scale ambiguity greatly improves the precision of QCD predictions and increases the sensitivity of searches for new physics at the LHC
The QCD/SM Working Group: Summary Report
M. Dobbs et al.
2004-08-05
Among the many physics processes at TeV hadron colliders, we look most eagerly for those that display signs of the Higgs boson or of new physics. We do so however amid an abundance of processes that proceed via Standard Model (SM) and in particular Quantum Chromodynamics (QCD) interactions, and that are interesting in their own right. Good knowledge of these processes is required to help us distinguish the new from the known. Their theoretical and experimental study teaches us at the same time more about QCD/SM dynamics, and thereby enables us to further improve such distinctions. This is important because it is becoming increasingly clear that the success of finding and exploring Higgs boson physics or other New Physics at the Tevatron and LHC will depend significantly on precise understanding of QCD/SM effects for many observables. To improve predictions and deepen the study of QCD/SM signals and backgrounds was therefore the ambition for our QCD/SM working group at this Les Houches workshop. Members of the working group made significant progress towards this on a number of fronts. A variety of tools were further developed, from methods to perform higher order perturbative calculations or various types of resummation, to improvements in the modeling of underlying events and parton showers. Furthermore, various precise studies of important specific processes were conducted. A significant part of the activities in Les Houches revolved around Monte Carlo simulation of collision events. A number of contributions in this report reflect the progress made in this area. At present a large number of Monte Carlo programs exist, each written with a different purpose and employing different techniques. Discussions in Les Houches revealed the need for an accessible primer on Monte Carlo programs, featuring a listing of various codes, each with a short description, but also providing a low-level explanation of the underlying methods. This primer has now been compiled and a
The QCD/SM working group: Summary report
Dobbs, Matt; Frixione, S.; Laenen, E.; De Roeck, A.; Tollefson, K.; Andersen, J.; Balazs, C.; Banfi, A.; Bernreuther, W.; Binoth, T.; Brandenburg, A.; Buttar, C.; Cao, C-H.; Cruz, A.; Dawson, I.; DelDuca, V.; Drollinger, V.; Dudko, L.; Eynck, T.; Field, R.; Grazzini, M.; Guillet, J.P.; Heinrich, G.; Huston, J.; Kauer, N.; Kidonakis, N.; Kulesza, A.; Lassila-Perini, K.; Magnea, L.; Mahmoudi, F.; Maina, E.; Maltoni, F.; Nolten, M.; Moraes, A.; Moretti, S.; Mrenna, S.; Nagy, Z.; Olness, F.; Puljak, I.; Ross, D.A.; Sabio-Vera, A.; Salam, G.P.; Sherstnev, A.; Si, Z.G.; Sjostrand, T.; Skands, P.; Thome, E.; Trocsanyi, Z.; Uwer, P.; Weinzierl, S.; Yuan, C.P.; Zanderighi,G.; Zanderighi, G.
2004-04-09
Among the many physics processes at TeV hadron colliders, we look most eagerly for those that display signs of the Higgs boson or of new physics. We do so however amid an abundance of processes that proceed via Standard Model (SM) and in particular Quantum Chromodynamics (QCD) interactions, and that are interesting in their own right. Good knowledge of these processes is required to help us distinguish the new from the known. Their theoretical and experimental study teaches us at the same time more about QCD/SM dynamics, and thereby enables us to further improve such distinctions. This is important because it is becoming increasingly clear that the success of finding and exploring Higgs boson physics or other New Physics at the Tevatron and LHC will depend significantly on precise understanding of QCD/SM effects for many observables. To improve predictions and deepen the study of QCD/SM signals and backgrounds was therefore the ambition for our QCD/SM working group at this Les Houches workshop. Members of the working group made significant progress towards this on a number of fronts. A variety of tools were further developed, from methods to perform higher order perturbative calculations or various types of resummation, to improvements in the modeling of underlying events and parton showers. Furthermore, various precise studies of important specific processes were conducted. A significant part of the activities in Les Houches revolved around Monte Carlo simulation of collision events. A number of contributions in this report reflect the progress made in this area. At present a large number of Monte Carlo programs exist, each written with a different purpose and employing different techniques. Discussions in Les Houches revealed the need for an accessible primer on Monte Carlo programs, featuring a listing of various codes, each with a short description, but also providing a low-level explanation of the underlying methods. This primer has now been compiled and a
Nuclear Forces from Lattice Quantum Chromodynamics Martin J. Savage
U.S. Department of Energy (DOE) all webpages (Extended Search)
Training (NELT) 2016 Nuclear Executive Leadership Training (NELT) 2016 September 12, 2016 - 1:13pm Addthis Nuclear Executive Leadership Training (NELT) 2016 The Department of Energy (DOE) Office of Enterprise Assessments, National Training Center (NTC) conducted its 16th annual Nuclear Executive Leadership Training (NELT) on August 15-19, 2016 in Washington, DC. Since the inception of NELT in 2005, approximately 375 senior personnel across the complex have participated in this event. The course
Light nuclei and hypernuclei from quantum chromodynamics in the...
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in the limit of SU(3) flavor symmetry Authors: Beane, S. R. ; Chang, E. ; Cohen, S. D. ; Detmold, W. ; Lin, H. W. ; Luu, T. C. ; Orginos, K. ; Parreo, A. ; Savage,...
QCD Phase Transitions, Volume 15
Schaefer, T.; Shuryak, E.
1999-03-20
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.
Gedanken Worlds without Higgs: QCD-Induced Electroweak Symmetry Breaking
Quigg, Chris; Shrock, Robert; /YITP, Stony Brook
2009-01-01
To illuminate how electroweak symmetry breaking shapes the physical world, we investigate toy models in which no Higgs fields or other constructs are introduced to induce spontaneous symmetry breaking. Two models incorporate the standard SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} U(1){sub Y} gauge symmetry and fermion content similar to that of the standard model. The first class--like the standard electroweak theory--contains no bare mass terms, so the spontaneous breaking of chiral symmetry within quantum chromodynamics is the only source of electroweak symmetry breaking. The second class adds bare fermion masses sufficiently small that QCD remains the dominant source of electroweak symmetry breaking and the model can serve as a well-behaved low-energy effective field theory to energies somewhat above the hadronic scale. A third class of models is based on the left-right-symmetric SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} {circle_times} U(1)B?L gauge group. In a fourth class of models, built on SU(4){sub PS} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} gauge symmetry, lepton number is treated as a fourth color. Many interesting characteristics of the models stem from the fact that the effective strength of the weak interactions is much closer to that of the residual strong interactions than in the real world. The Higgs-free models not only provide informative contrasts to the real world, but also lead us to consider intriguing issues in the application of field theory to the real world.
Dudek, Jozef J.; Edwards, Robert G.
2012-03-21
In this study, 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 numbersmore » $$N_{1/2^+},\\,N_{1/2^+},\\,N_{3/2^+},\\, N_{3/2^+},\\,N_{5/2^+},\\,$$ 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.« less
Quenched hadron spectrum of QCD
Kim, Seyong
1992-12-01
We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32{sup 3} {times} 64 lattice volume at {beta} = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the {triangle} masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.
Quenched hadron spectrum of QCD
Kim, Seyong.
1992-12-01
We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32[sup 3] [times] 64 lattice volume at [beta] = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the [triangle] masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.
H. David Politzer, Asymptotic Freedom, and Strong Interaction
Office of Scientific and Technical Information (OSTI)
... showed that in quantum chromodynamics (QCD), quarks are held together strongly when separated by a distance comparable to the size of a proton, explaining quark confinement. ...
U.S. Department of Energy (DOE) all webpages (Extended Search)
... Accelerator Laboratory FNAL) hosting a distributed Lattice QCD (quantum chromodynamics) Computing Facility consisting of 10-100 teraflops class clusters tuned to the ...
National labs offer computing time to Japanese physicists | Jefferson...
U.S. Department of Energy (DOE) all webpages (Extended Search)
Virginia will be made available to the Japanese Lattice Quantum Chromodynamics community. ... Such calculations require enormous computing power, and as a result groups of QCD ...
Karsch,F.; Kharzeev, D.; Molnar, K.; Petreczky, P.; Teaney, D.
2008-04-21
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.
QCD in the Hartree approximation
Biro f , T. S.
1989-04-01
For QCD and expansion of the full quantum theory on a variational background forcing vanishing expectation values for colour fields is considered. This approach at low temperature (strong coupling) describes a colourless condensate of gluonic Cooper pairs. Their binding energy cancels exactly their background generated gluon mass, restoring the gauge symmetry. At high temperature (weak coupling) only a perturbative gluon plasma exists. The vacuum energy density and the phase transition temperature are related to the pairing energy. Our results scale according to asymptotic freedom. /copyright/ Academic Press, Inc. 1989
Norniella, Olga; /Barcelona, IFAE
2005-01-01
Recent QCD measurements from the CDF collaboration at the Tevatron are presented, together with future prospects as the luminosity increases. The measured inclusive jet cross section is compared to pQCD NLO predictions. Precise measurements on jet shapes and hadronic energy flows are compared to different phenomenological models that describe gluon emissions and the underlying event in hadron-hadron interactions.
QCD PHASE TRANSITIONS-VOLUME 15.
SCHAFER,T.
1998-11-04
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.
Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and...
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Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and Conformal Quantum Mechanics Dosch, Hans Gunter; U. Heidelberg, ITP; Brodsky, Stanley J.; SLAC; de Teramond, Guy F.;...
Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and...
Office of Scientific and Technical Information (OSTI)
Modified Anti-de-Sitter Metric, Light-Front Quantized QCD, and Conformal Quantum Mechanics Citation Details In-Document Search Title: Modified Anti-de-Sitter Metric, Light-Front...
Lattice QCD and NERSC requirements
U.S. Department of Energy (DOE) all webpages (Extended Search)
QCD and NERSC requirements Rich Brower, Steven Gottlieb and Doug Toussaint November 26, 2012 Rich Brower, Steven Gottlieb and Doug Toussaint () Lattice QCD at NERSC November 26, 2012 1 / 17 Lattice Gauge Theory at NERSC First-principles computations in QCD Computations in other strongly coupled field theories Find hadronic factors to get fundamental physics from experiments Understand structure and interactions of hadrons Understand QCD: confinement and chiral symmetry breaking Other strongly
Seymour, M.H.
1996-02-01
Many analyses at the collider utilize the hadronic jets that are the footprints of QCD partons. These are used both to study the QCD processes themselves and increasingly as tools to study other physics, for example top mass reconstruction. However, jets are not fundamental degrees of freedom in the theory, so we need an {ital operational} {ital jet} {ital definition} and {ital reliable} {ital methods} {ital to} {ital calculate} {ital their} {ital properties}. This talk covers both of these important areas of jet physics. {copyright} {ital 1996 American Institute of Physics.}
Nuclear Physics from Lattice QCD
U.S. Department of Energy (DOE) all webpages (Extended Search)
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
Brodsky, Stanley J.; Deshpande, Abhay L.; Gao, Haiyan; McKeown, Robert D.; Meyer, Curtis A.; Meziani, Zein-Eddine; Milner, Richard G.; Qiu, Jianwei; Richards, David G.; Roberts, Craig D.
2015-02-26
This White Paper presents the recommendations and scientific conclusions from the Town Meeting on QCD and Hadronic Physics that took place in the period 13-15 September 2014 at Temple University as part of the NSAC 2014 Long Range Planning process. The meeting was held in coordination with the Town Meeting on Phases of QCD and included a full day of joint plenary sessions of the two meetings. The goals of the meeting were to report and highlight progress in hadron physics in the seven years since the 2007 Long Range Plan (LRP07), and present a vision for the future by identifying the key questions and plausible paths to solutions which should define the next decade. The introductory summary details the recommendations and their supporting rationales, as determined at the Town Meeting on QCD and Hadron Physics, and the endorsements that were voted upon. The larger document is organized as follows. Section 2 highlights major progress since the 2007 LRP. It is followed, in Section 3, by a brief overview of the physics program planned for the immediate future. Finally, Section 4 provides an overview of the physics motivations and goals associated with the next QCD frontier: the Electron-Ion-Collider.
QCD coupling constants and VDM
Erkol, G.; Ozpineci, A.; Zamiralov, V. S.
2012-10-23
QCD sum rules for coupling constants of vector mesons with baryons are constructed. The corresponding QCD sum rules for electric charges and magnetic moments are also derived and with the use of vector-meson-dominance model related to the coupling constants. The VDM role as the criterium of reciprocal validity of the sum rules is considered.
None
2016-07-12
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.
Murray Gell-Mann, the Eightfold Way, Quarks, and Quantum Chromodynamic...
Office of Scientific and Technical Information (OSTI)
Interview with Murray Gell-Mann, Caltech Murray Gell-Mann On Emergence (video) 2005 Albert Einstein Medal Murray Gell-Mann 1929 - , PBS Murray Gell-Mann, Emory University...
New Perspectives for QCD Physics at the LHC
Brodsky, Stanley J.; /SLAC /Stanford U. /Southern Denmark U., CP3-Origins
2011-02-07
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{sub T} photon plus charm-jet events observed at the Tevatron and imply a large production rate for 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}. 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.
Variational perturbation theory and nonperturbative calculations in QCD
Solovtsova, O. P.
2013-10-15
A nonperturbative approach based on the variational perturbation theory in quantum chromodynamics is developed. The variational series is different from the conventional perturbative expansion and can be used to go beyond the weak-coupling regime. The approach suggested takes into account the summation of threshold singularities and the involvement of nonperturbative light quark masses. Phenomenological applications of this approach to describe physical quantities connected with the hadronic {tau}-decay data: the R{sub {tau}} ratio, the light-quark Adler function, and the smeared R{sub {Delta}} function are presented. The description of examined quantities includes an infrared region and, therefore, they cannot be directly calculated within the standard perturbation theory. It is shown that in spite of this fact the approach suggested gives a rather good result for these quantities down to the lowest energy scale.
Spectroscopy of charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2015-01-01
We present the ground and excited state spectra of singly, doubly and triply charmed baryons by using dynamical lattice QCD. A large set of baryonic operators that respect the symmetries of the lattice and are obtained after subduction from their continuum analogues are utilized. Using novel computational techniques correlation functions of these operators are generated and the variational method is exploited to extract excited states. The lattice spectra that we obtain have baryonic states with well-defined total spins up to 7/2 and the low lying states remarkably resemble the expectations of quantum numbers from SU(6) x O(3) symmetry. Various energy splittings between the extracted states, including splittings due to hyperfine as well as spin-orbit coupling, are considered and those are also compared against similar energy splittings at other quark masses.
Results from D0: dijet angular distributions, dijet mass cross...
Office of Scientific and Technical Information (OSTI)
At hadron colliders, jet production has one of the highest cross section and is therefore an ideal place to test the predictions of perturbative Quantum chromodynamics (pQCD). The ...
Fermilab | Science at Fermilab | Computing | High-performance...
U.S. Department of Energy (DOE) all webpages (Extended Search)
In parallel computing, computations are divided up so that many computers can work on the same problem at once. Lattice Quantum Chromodynamics, or Lattice QCD, is one area of ...
Anti-proton annihilation in nuclei as a probe of QCD
Brodsky, S.J.
1990-09-01
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.
Twistor inspired techniques in QCD
Duhr, C.
2008-08-29
I present a short review of the new twistor inspired techniques in perturbative QCD, which are the result of Witten's conjecture of a duality between twistors and string theory. I give an introduction to the main two tree-level techniques, the BCFW recursion and the CSW formalism, and show how the idea of using on-shell QCD amplitudes evaluated for complex momenta can lead to efficient techniques to perform analytic computations. Finally, I briefly discuss how these ideas can be applied to loop calculations if they are combined to the generalized unitarity approach.
Basics of QCD perturbation theory
Soper, D.E.
1997-06-01
This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs.
Rotor spectra, berry phases, and monopole fields: From antiferromagnets to QCD
Chandrasekharan, S.; Jiang, F.-J.; Wiese, U.-J.; Pepe, M.
2008-10-01
The order parameter of a finite system with a spontaneously broken continuous global symmetry acts as a quantum mechanical rotor. Both antiferromagnets with a spontaneously broken SU(2){sub s} spin symmetry and massless QCD with a broken SU(2){sub L}xSU(2){sub R} chiral symmetry have rotor spectra when considered in a finite volume. When an electron or hole is doped into an antiferromagnet or when a nucleon is propagating through the QCD vacuum, a Berry phase arises from a monopole field and the angular momentum of the rotor is quantized in half-integer units.
Hadron Structure from Lattice QCD
U.S. Department of Energy (DOE) all webpages (Extended Search)
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
Signatures of confinement in axial gauge QCD
Lenz, F.; Moniz, Ernest J.; Thies, M.
1995-09-01
A comparative dynamical study of axial gauge QED and QCD is presented. Elementary excitations associated with particular field configurations are investigated. Gluonic excitations analogous to linearly polarized photons are shown to acquire infinite energy. Suppression of this class of excitations in QCD results from quantization of the chromo-electric flux and is interpreted as a dual Meissner effect, i.e., as expulsion from the QCD vacuum of chromo-electric fields which are constant over significant distances. This interpretation is supported by a comparative evaluation of the interaction energy of static charges in the axial gauge representation of QED and QCD. {copyright} 1995 Academic Press, Inc.
None
2011-10-06
Modern QCD - Lecture 2 We will start discussing the matter content of the theory and revisit the experimental measurements that led to the discovery of quarks. We will then consider a classic QCD observable, the R-ratio, and use it to illustrate the appearance of UV divergences and the need to renormalize the coupling constant of QCD. We will then discuss asymptotic freedom and confinement. Finally, we will examine a case where soft and collinear infrared divergences appear, will discuss the soft approximation in QCD and will introduce the concept of infrared safe jets.
Collisional energy loss above the critical temperature in QCD...
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Collisional energy loss above the critical temperature in QCD Citation Details In-Document Search Title: Collisional energy loss above the critical temperature in QCD Authors: Lin, ...
Equation of State from Lattice QCD Calculations (Conference)...
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Conference: Equation of State from Lattice QCD Calculations Citation Details In-Document Search Title: Equation of State from Lattice QCD Calculations You are accessing a...
QCD Prediction for Heavy Boson Transverse Momentum Distributions...
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QCD Prediction for Heavy Boson Transverse Momentum Distributions Citation Details In-Document Search Title: QCD Prediction for Heavy Boson Transverse Momentum Distributions We ...
Solvable models and hidden symmetries in QCD
Yepez-Martinez, Tochtli; Hess, P. O.; Civitarese, O.; Lerma H., S.
2010-12-23
We show that QCD Hamiltonians at low energy exhibit an SU(2) structure, when only few orbital levels are considered. In case many orbital levels are taken into account we also find a semi-analytic solution for the energy levels of the dominant part of the QCD Hamiltonian. The findings are important to propose the structure of phenomenological models.
QCD tests in electron-positron scattering
Maruyama, T.
1995-11-01
Recent results on QCD tests at the Z{sup o} resonance are described. Measurements of Color factor ratios, and studies of final state photon radiation are performed by the LEP experiments. QCD tests using a longitudinally polarized beam are reported by the SLD experiment.
Light-front holographic QCD and emerging confinement
Brodsky, Stanley J.; de Téramond, Guy F.; Dosch, Hans Günter; Erlich, Joshua
2015-05-21
In this study we explore the remarkable connections between light-front dynamics, its holographic mapping to gravity in a higher-dimensional anti-de Sitter (AdS) space, and conformal quantum mechanics. This approach provides new insights into the origin of a fundamental mass scale and the physics underlying confinement dynamics in QCD in the limit of massless quarks. The result is a relativistic light-front wave equation for arbitrary spin with an effective confinement potential derived from a conformal action and its embedding in AdS space. This equation allows for the computation of essential features of hadron spectra in terms of a single scale. The light-front holographic methods described here give a precise interpretation of holographic variables and quantities in AdS space in terms of light-front variables and quantum numbers. This leads to a relation between the AdS wave functions and the boost-invariant light-front wave functions describing the internal structure of hadronic bound-states in physical spacetime. The pion is massless in the chiral limit and the excitation spectra of relativistic light-quark meson and baryon bound states lie on linear Regge trajectories with identical slopes in the radial and orbital quantum numbers. In the light-front holographic approach described here currents are expressed as an infinite sum of poles, and form factors as a product of poles. At large q^{2} the form factor incorporates the correct power-law fall-off for hard scattering independent of the specific dynamics and is dictated by the twist. At low q^{2} the form factor leads to vector dominance. The approach is also extended to include small quark masses. We briefly review in this report other holographic approaches to QCD, in particular top-down and bottom-up models based on chiral symmetry breaking. We also include a discussion of open problems and future applications.
Lattice QCD with Domain Decomposition on Intel Xeon Phi Co-Processors
Heybrock, Simon; Joo, Balint; Kalamkar, Dhiraj D.; Smelyanskiy, Mikhail; Vaidyanathan, Karthikeyan; Wettig, Tilo; Dubey, Pradeep
2014-12-01
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.
QCD mechanisms for heavy particle production
Brodsky, S.J.
1985-09-01
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.
None
2016-07-12
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.
Some New/Old Approaches to QCD
DOE R&D Accomplishments [OSTI]
Gross, D. J.
1992-11-01
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.
QCD and hard diffraction at the LHC
Albrow, Michael G.; /Fermilab
2005-09-01
As an introduction to QCD at the LHC the author gives an overview of QCD at the Tevatron, emphasizing the high Q{sup 2} frontier which will be taken over by the LHC. After describing briefly the LHC detectors the author discusses high mass diffraction, in particular central exclusive production of Higgs and vector boson pairs. The author introduces the FP420 project to measure the scattered protons 420m downstream of ATLAS and CMS.
Gao, Jun; Zhu, Hua Xing
2014-12-17
We report on a calculation of the vector current contributions to the electroweak production of top quark pairs in e^{+}e^{–} annihilation at next-to-next-to-leading order in quantum chromodynamics. Our setup is fully differential and can be used to calculate any infrared-safe observable. The real emission contributions are handled by a next-to-next-to-leading order generalization of the phase-space slicing method. As a result, we demonstrate the power of our technique by considering its application to various inclusive and exclusive observables.
Novel QCD Phenomena at JLab (Conference) | SciTech Connect
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DOE Contract Number: AC02-76SF00515 Resource Type: Conference Resource Relation: Conference: Presented at QCD Evolution Workshop (QCD 2015), 26-30 May 2015. Newport News, VA, USA ...
Electroweak and QCD corrections to top-pair hadroproduction in...
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Electroweak and QCD corrections to top-pair hadroproduction in association with heavy bosons Citation Details In-Document Search Title: Electroweak and QCD corrections to top-pair ...
Electromagnetically superconducting phase of QCD vacuum induced by strong magnetic field
Chernodub, M. N. [CNRS, Laboratoire de Mathematiques et Physique Theorique, Universite Francois-Rabelais Tours, Federation Denis Poisson, Parc de Grandmont, 37200 Tours (France); Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent (Belgium)
2011-05-23
In this talk we discuss our recent suggestion that the QCD vacuum in a sufficiently strong magnetic field (stronger than 10{sup 16} Tesla) may undergo a spontaneous transition to an electromagnetically superconducting state. The possible superconducting state is anisotropic (the vacuum exhibits superconductivity only along the axis of the uniform magnetic field) and inhomogeneous (in the transverse directions the vacuum structure shares similarity with the Abrikosov lattice of an ordinary type-II superconductor). The electromagnetic superconductivity of the QCD vacuum is suggested to occur due to emergence of specific quark-antiquark condensates which carry quantum numbers of electrically charged rho mesons. A Lorentz-covariant generalization of the London transport equations for the magnetic-field-induced superconductivity is given.
JLab Completes 100th Experiment | Jefferson Lab
U.S. Department of Energy (DOE) all webpages (Extended Search)
Completes 100th Experiment JLab Completes 100th Experiment The experiment, titled "Quark Propagation through Cold QCD Matter," began its run in December 2003 and wrapped up in early March. It probed Quantum Chromodynamics (QCD), a fundamental theory of particle physics that describes the interactions of quarks and gluons - the basic building blocks of matter. A property of QCD, called confinement, states that no quark can ever be found alone. Instead, quarks combine in pairs or
Light-front holographic QCD and emerging confinement
Brodsky, Stanley J.; de Téramond, Guy F.; Dosch, Hans Günter; Erlich, Joshua
2015-05-21
In this study we explore the remarkable connections between light-front dynamics, its holographic mapping to gravity in a higher-dimensional anti-de Sitter (AdS) space, and conformal quantum mechanics. This approach provides new insights into the origin of a fundamental mass scale and the physics underlying confinement dynamics in QCD in the limit of massless quarks. The result is a relativistic light-front wave equation for arbitrary spin with an effective confinement potential derived from a conformal action and its embedding in AdS space. This equation allows for the computation of essential features of hadron spectra in terms of a single scale. Themore » light-front holographic methods described here give a precise interpretation of holographic variables and quantities in AdS space in terms of light-front variables and quantum numbers. This leads to a relation between the AdS wave functions and the boost-invariant light-front wave functions describing the internal structure of hadronic bound-states in physical spacetime. The pion is massless in the chiral limit and the excitation spectra of relativistic light-quark meson and baryon bound states lie on linear Regge trajectories with identical slopes in the radial and orbital quantum numbers. In the light-front holographic approach described here currents are expressed as an infinite sum of poles, and form factors as a product of poles. At large q2 the form factor incorporates the correct power-law fall-off for hard scattering independent of the specific dynamics and is dictated by the twist. At low q2 the form factor leads to vector dominance. The approach is also extended to include small quark masses. We briefly review in this report other holographic approaches to QCD, in particular top-down and bottom-up models based on chiral symmetry breaking. We also include a discussion of open problems and future applications.« less
Nonperturbative QCD corrections to electroweak observables
Dru B Renner, Xu Feng, Karl Jansen, Marcus Petschlies
2011-12-01
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.
The Top Quark, QCD, And New Physics.
DOE R&D Accomplishments [OSTI]
Dawson, S.
2002-06-01
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.
None
2016-07-12
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.
QCD at the Tevatron: Jets and fragmentation
V. Daniel Elvira
2001-09-27
At the Fermilab Tevatron energies, ({radical} s=1800 GeV and {radical} s = 630 GeV), jet production is the dominant process. During the period 1992-1996, the D0 and CDF experiments accumulated almost 100 pb{sup -1} of data and performed the most accurate jet production measurements up to this date. These measurements and the NLO-QCD theoretical predictions calculated during the last decade, have improved our understanding of QCD, our knowledge of the proton structure, and pushed the limit to the scale associated with quark compositeness to 2.4-2.7 TeV. In this paper, we present the most recent published and preliminary measurements on jet production and fragmentation by the D0 and CDF collaborations.
Bootstrapping One-Loop QCD Amplitudes
Berger, Carola F.; /SLAC
2006-09-08
We review the recently developed bootstrap method for the computation of high-multiplicity QCD amplitudes at one loop. We illustrate the general algorithm step by step with a six-point example. The method combines (generalized) unitarity with on-shell recursion relations to determine the not cut-constructible, rational terms of these amplitudes. Our bootstrap approach works for arbitrary configurations of gluon helicities and arbitrary numbers of external legs.
Full CKM matrix with lattice QCD
Okamoto, Masataka; /Fermilab
2004-12-01
The authors show that it is now possible to fully determine the CKM matrix, for the first time, using lattice QCD. |V{sub cd}|, |V{sub cs}|, |V{sub ub}|, |V{sub cb}| and |V{sub us}| are, respectively, directly determined with the lattice results for form factors of semileptonic D {yields} {pi}lv, D {yields} Klv, B {yields} {pi}lv, B {yields} Dlv and K {yields} {pi}lv decays. The error from the quenched approximation is removed by using the MILC unquenced lattice gauge configurations, where the effect of u, d and s quarks is included. The error from the ''chiral'' extrapolation (m{sub l} {yields} m{sub ud}) is greatly reduced by using improved staggered quarks. The accuracy is comparable to that of the Particle Data Group averages. In addition, |V{sub ud}|, |V{sub ts}|, |V{sub ts}| and |V{sub td}| are determined by using unitarity of the CKM matrix and the experimental result for sin (2{beta}). In this way, they obtain all 9 CKM matrix elements, where the only theoretical input is lattice QCD. They also obtain all the Wolfenstein parameters, for the first time, using lattice QCD.
Heavy Quarks, QCD, and Effective Field Theory Thomas Mehen 72...
Office of Scientific and Technical Information (OSTI)
Heavy Quarks, QCD, and Effective Field Theory Thomas Mehen 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS Heavy Quarks, Quarkonium,...
Heavy Quarks, QCD, and Effective Field Theory (Technical Report...
Office of Scientific and Technical Information (OSTI)
The perturbative physics can then be calculated using QCD perturbation theory. Universal functions with precise fi eld theoretic de nitions describe the nonperturbative physics. In ...
Quantum simulations of strongly coupled quark-gluon plasma
Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.
2012-06-15
A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasi-particles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the classical molecular dynamics by Gelman, Shuryak, and Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state. The results indicate that the QGP reveals liquid-like rather than gaslike properties. Quantum effects turned out to be of prime importance in these simulations.
Quarkyonic Matter and the Revised Phase Diagram of QCD
McLerran,L.
2009-03-30
At high baryon number density, it has been proposed that a new phase of QCD matter controlsthe physics. This matter is confining but can have densities much larger than 3QCD. Its existenceis argued from large Nc approximations, and model computations. It is approximately chirallysymmetric.
Lattice QCD production on commodity clusters at Fermilab
D. Holmgren et al.
2003-09-30
We describe the construction and results to date of Fermilab's three Myrinet-networked lattice QCD production clusters (an 80-node dual Pentium III cluster, a 48-node dual Xeon cluster, and a 128-node dual Xeon cluster). We examine a number of aspects of performance of the MILC lattice QCD code running on these clusters.
None
2011-10-06
Modern QCD - Lecture 5 We will introduce and discuss in some detail the two main classes of jets: cone type and sequential-recombination type. We will discuss their basic properties, as well as more advanced concepts such as jet substructure, jet filtering, ways of optimizing the jet radius, ways of defining the areas of jets, and of establishing the quality measure of the jet-algorithm in terms of discriminating power in specific searches. Finally we will discuss applications for Higgs searches involving boosted particles.
Lattice QCD | Argonne Leadership Computing Facility
U.S. Department of Energy (DOE) all webpages (Extended Search)
The form factor for the decay of a kaon into a pion and two leptons The form factor for the decay of a kaon into a pion and two leptons. It yields the most precise determination so far of the CKM matrix element, |Vus|. A. Bazavov et al., Phys.Rev. Lett. 112 (2014) 112001; e-Print: arXiv:1312.1228 Lattice QCD PI Name: Paul Mackenzie PI Email: mackenzie@fnal.gov Institution: Fermilab Allocation Program: INCITE Allocation Hours at ALCF: 180 Million Year: 2016 Research Domain: Physics For this
Two nucleon systems at mπ~450MeV from lattice QCD
Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Beane, Silas R.; Chang, Emmanuel; Detmold, William
2015-12-23
Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass ofmore » $$m_\\pi\\sim 450~{\\rm MeV}$$ in three spatial volumes using $n_f=2+1$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $$B_d = 14.4^{+3.2}_{-2.6} ~{\\rm MeV}$$, while the dineutron is bound by $$B_{nn} = 12.5^{+3.0}_{-5.0}~{\\rm MeV}$$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the 1S0 and 3S1-3D1 channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the effective range expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. Thus, the extracted phase shifts allow for matching to nuclear effective field theories, from which low energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann–Okubo mass relation.« less
Brodsky, Stanley J.; de Teramond, Guy F.; Deur, Alexandre P.; Dosch, Hans G.
2015-09-01
The valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a relativistic equation of motion with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. If one requires that the effective action which underlies the QCD Lagrangian remains conformally invariant and extends the formalism of de Alfaro, Fubini and Furlan to light front Hamiltonian theory, the potential U has a unique form of a harmonic oscillator potential, and a mass gap arises. The result is a nonperturbative relativistic light-front quantum mechanical wave equation which incorporates color confinement and other essential spectroscopic and dynamical features of hadron physics, including a massless pion for zero quark mass and linear Regge trajectories with the same slope in the radial quantum number n and orbital angular momentum L. Only one mass parameter κ appears. Light-front holography thus provides a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. We also show how the mass scale κ underlying confinement and hadron masses determines the scale ΛMS¯¯¯¯ controlling the evolution of the perturbative QCD coupling. The relation between scales is obtained by matching the nonperturbative dynamics, as described by an effective conformal theory mapped to the light-front and its embedding in AdS space, to the perturbative QCD regime computed to four-loop order. The result is an effective coupling defined at all momenta. The predicted value ΛMS¯¯¯¯=0.328±0.034 GeV is in agreement with the world average 0.339±0.010 GeV. The analysis applies to any renormalization scheme.
QCD, OZI, and evidence for glueballs
Lindenbaum, S.J.
1981-01-01
The characteristics expected from low Q-QCD for the behavior of glueballs and the OZI rule is discussed. The reaction ..pi../sup -/p ..-->.. phi phi n represents on OZI forbidden (hairpin) diagram. It has been observed at the Brookhaven National Laboratory multiparticle spectrometer by the Brookhaven National Laboratory/City College of New York group. The author has shown that the expected OZI suppression is essentially entirely absent and in fact the Isobar Model which does not contain OZI suppression quantitatively explains the observed results. A general evaluation of the special characteristics of the data compared to other related reactions plus the foregoing facts leads the author to conclude that the intervention of glueball resonances is the likely explanation in the context of QCD. Other explanations are shown to be improbable. In particular the hypothesis that decay of a radial excitation of the eta' is responsible for lack of OZI suppression is ruled out. Planned experiments with the purpose of explicity discovering glueballs will be discussed. The OZI rule peculiarities such as violation of crossing symmetry and unitarity are attributed to color confinement.
Charmed bottom baryon spectroscopy from lattice QCD
Brown, Zachary S.; Detmold, William; Meinel, Stefan; Orginos, Kostas
2014-11-19
In this study, 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 physicalmore » 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.« less
Charmed bottom baryon spectroscopy from lattice QCD
Brown, Zachary S.; Detmold, William; Meinel, Stefan; Orginos, Kostas
2014-11-19
In this study, 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 J^{P} = 1/2^{+} and J^{P} = 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/m_{Q} 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.
Charmed bottom baryon spectroscopy from lattice QCD
Brown, Zachary S.; Detmold, William; Meinel, Stefan; Orginos, Kostas
2014-11-01
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/m_{Q} 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.
Scharre, D.L.
1982-01-01
It is expected from quantum chromodynamics (QCD) that glueballs, bound states which contain gluons but no valence quarks, should exist. To date, no conclusive evidence for glueballs has been presented. After a brief review of the expected properties and experimental signatures of glueballs the status of some glueball candidate states are discussed.
AdS/QCD and Applications of Light-Front Holography
Brodsky, Stanley J.; Cao, Fu-Guang; de Teramond, Guy F.; /Costa Rica U.
2012-02-16
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.
U.S. Department of Energy (DOE) all webpages (Extended Search)
MILC MILC Description The benchmark code MILC represents part of a set of codes written by the MIMD Lattice Computation (MILC) collaboration used to study quantum chromodynamics (QCD), the theory of the strong interactions of subatomic physics. It performs simulations of four dimensional SU(3) lattice gauge theory on MIMD parallel machines. "Strong interactions" are responsible for binding quarks into protons and neutrons and holding them all together in the atomic nucleus. QCD
Feynman rules for Coulomb gauge QCD
Andrasi, A.; Taylor, J.C.
2012-10-15
The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel. - Highlights: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.
U.S. Department of Energy (DOE) all webpages (Extended Search)
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
Meson mass decomposition from lattice QCD (Journal Article) ...
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Citation Details In-Document Search Title: Meson mass decomposition from lattice QCD Authors: Yang, Yi-Bo ; Chen, Ying ; Draper, Terrence ; Gong, Ming ; Liu, Keh-Fei ; Liu, ...
Tevatron-for-LHC Report of the QCD Working Group
Albrow, Michael G.; Begel, M.; Bourilkov, D.; Campanelli, M.; Chlebana, F.; De Roeck, A.; Dittmann, J.R.; Ellis, S.D.; Field, B.; Field, R.; Gallinaro, M.; /Fermilab /Rochester U. /Florida U. /Geneva U. /CERN /Baylor U. /Washington U., Seattle /Florida State U. /Rockefeller U. /Prague, Tech. U. /Michigan State U.
2006-10-01
The experiments at Run 2 of the Tevatron have each accumulated over 1 fb{sup -1} of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focused on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.
New analogies between extreme QCD and cold atoms
Nishida, Yusuke
2012-08-15
We discuss two new analogies between extreme QCD and cold atoms. One is the analogue of 'hard probes' in cold atoms. The other is the analogue of 'quark-hadron continuity' in cold atoms.
Pion polarizabilities and volume effects in lattice QCD
Hu Jie; Jiang Fujiun; Tiburzi, Brian C.
2008-01-01
We use chiral perturbation theory to study the extraction of pion electromagnetic polarizabilities from lattice QCD. Chiral extrapolation formulae are derived for partially quenched QCD, and quenched QCD simulations. On a torus, volume dependence of electromagnetic current correlators is complicated by SO(4) breaking, as well as photon zero-mode interactions. We determine finite volume corrections to the Compton scattering tensor of pions. We argue, however, that such results cannot be used to ascertain volume corrections to polarizabilities determined in lattice QCD with background field methods. Connection is lacking because small momentum expansions are not permitted in finite volume. Our argument also applies to form factors. Volume effects for background field calculations of electromagnetic moments cannot be deduced from finite volume form factors.
Charm and bottom hadronic form factors with QCD sum rules
Bracco, M. E.; Rodrigues, B. O.; Cerqueira, A. Jr.
2013-03-25
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.
Searching for the rules that govern hadron construction
Shepherd, Matthew R.; Dudek, Jozef J.; Mitchell, Ryan E.
2016-06-22
Just as quantum electrodynamics describes how electrons are bound in atoms by the electromagnetic force, mediated by the exchange of photons, quantum chromodynamics (QCD) describes how quarks are bound inside hadrons by the strong force, mediated by the exchange of gluons. QCD seems to allow hadrons constructed from increasingly many quarks to exist, just as atoms with increasing numbers of electrons exist, yet such complex constructions seemed, until recently, not to be present in nature. In this paper, we describe advances in the spectroscopy of mesons that are refining our understanding of the rules for predicting hadron structure from QCD.
Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena
Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.
2012-02-16
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
QCD analysis of $W$- and $Z$-boson production at Tevatron (Journal...
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QCD analysis of W- and Z-boson production at Tevatron Citation Details In-Document Search Title: QCD analysis of W- and Z-boson production at Tevatron You are accessing...
Constructing QCD one-loop amplitudes (Conference) | SciTech Connect
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Conference: Constructing QCD one-loop amplitudes Citation Details In-Document Search Title: Constructing QCD one-loop amplitudes In the context of constructing one-loop amplitudes ...
Wong's equations and the small x effective action in QCD (Journal...
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Wong's equations and the small x effective action in QCD Citation Details In-Document Search Title: Wong's equations and the small x effective action in QCD We propose a new form ...
Toward large N thermal QCD from dual gravity: The heavy quarkonium...
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Toward large N thermal QCD from dual gravity: The heavy quarkonium potential Citation Details In-Document Search Title: Toward large N thermal QCD from dual gravity: The heavy ...
QCD tests of the puzzling scalar mesons
Narison, Stephan
2006-06-01
Motivated by several recent data, we test the QCD spectral sum rules (QSSR) predictions based on different proposals (qq, qqqq, and gluonium) for the nature of scalar mesons. In the I=1 and 1/2 channels, the unusual wrong splitting between the a{sub 0}(980) and {kappa}(900) and the a{sub 0}(980) width can be understood from QSSR within a qq assignment. However, none of the qq and qqqq results can explain the large {kappa} width, which may suggest that it can result from a strong interference with nonresonant backgrounds. In the I=0 channel, QSSR and some low-energy theorems (LET) require the existence of a low mass gluonium {sigma}{sub B}(1 GeV) coupled strongly to Goldstone boson pairs which plays in the U(1){sub V} channel, a similar role as the {eta}{sup '} for the value of the U(1){sub A} topological charge. The observed {sigma}(600) and f{sub 0}(980) mesons result from a maximal mixing between the gluonium {sigma}{sub B} and qq (1 GeV) mesons, a mixing scheme which passes several experimental tests. Okubo-Zweig-Izuki (OZI) violating J/{psi}{yields}{phi}{pi}{sup +}{pi}{sup -}, D{sub s}{yields}3{pi} decays, and J/{psi}{yields}{gamma}S glueball filter processes may indicate that the f{sub 0}(1500), f{sub 0}(1710), and f{sub 0}(1790) have significant gluonium components in their wave functions, while the f{sub 0}(1370) is mostly qq. Tests of these results can be provided by the measurements of the pure gluonium {eta}{sup '}{eta} and 4{pi} specific U(1){sub A} decay channels.
Search for the pentaquark resonance signature in lattice QCD
B. G. Lasscock; J. Hedditch; Derek Leinweber; Wolodymyr Melnitchouk; Anthony Thomas; A. G. Williams; R. D. Young; James Zanotti
2005-02-01
Claims concerning the possible discovery of the {Theta}{sup +} pentaquark, with minimal quark content uudd{bar s}, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various pentaquark interpolating fields in the literature and create a new candidate ideal for lattice QCD simulations. Using these interpolating fields we attempt to isolate a signal for a five-quark resonance. Calculations are performed using improved actions on a large 20{sup 3} x 40 lattice in the quenched approximation. The standard lattice resonance signal of increasing attraction between baryon constituents for increasing quark mass is not observed for spin-1/2 pentaquark states. We conclude that evidence supporting the existence of a spin-1/2 pentaquark resonance does not exist in quenched QCD.
Search for the pentaquark resonance signature in lattice QCD
B. G. Lasscock; J. Hedditch; D. B. Leinweber; W. Melnitchouk; A. W. Thomas; A. G. Williams; R. D. Young; J. M. Zanotti
2005-03-01
Claims concerning the possible discovery of the $\\Theta^+$ pentaquark, with minimal quark content $uudd\\bar{s}$, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various pentaquark interpolating fields in the literature and create a new candidate ideal for lattice QCD simulations. Using these interpolating fields we attempt to isolate a signal for a five-quark resonance. Calculations are performed using improved actions on a large $20^{3} \\times 40$ lattice in the quenched approximation. The standard lattice resonance signal of increasing attraction between baryon constituents for increasing quark mass is not observed for spin-1/2 pentaquark states. We conclude that evidence supporting the existence of a spin-1/2 pentaquark resonance does not exist in quenched QCD.
Merging weak and QCD showers with matrix elements
Christiansen, Jesper Roy; Prestel, Stefan
2016-01-22
In this study, we present a consistent way of combining associated weak boson radiation in hard dijet events with hard QCD radiation in Drell–Yan-like scatterings. This integrates multiple tree-level calculations with vastly different cross sections, QCD- and electroweak parton-shower resummation into a single framework. The new merging strategy is implemented in the P ythia event generator and predictions are confronted with LHC data. Improvements over the previous strategy are observed. Results of the new electroweak-improved merging at a future 100 TeV proton collider are also investigated.
New insight on global QCD fits using Regge theory
Soyez, G.
2005-06-14
In global QCD fits, one has to choose an initial parton distribution at Q{sup 2} = Q{sub 0}{sup 2}. I shall argue that the initial condition chosen in usual standard sets is inconsistent with analytic S-matrix theory. I shall show how one can combine these two approaches, leading to a Regge-compatible next-to-leading order global QCD fit. This allows one to extend the parametrisation in the low-Q2 region. Finally, I shall discuss how it it possible to use the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equation to obtain information on Regge models at high Q2.
Exact and approximate fermion Green`s functions in QED and QCD
Fried, H.M. [Physics Department, Brown University, Providence, Rhode Island 02912 (United States)] [Physics Department, Brown University, Providence, Rhode Island 02912 (United States); Gabellini, Y. [Institut Non-Lineaire de Nice, 1361, Route des Lucioles, 06560 Valbonne (France)] [Institut Non-Lineaire de Nice, 1361, Route des Lucioles, 06560 Valbonne (France); McKellar, B.H.J. [School of Physics, University of Melbourne, Parkville, Victoria, 3052 (Australia)] [School of Physics, University of Melbourne, Parkville, Victoria, 3052 (Australia)
1995-06-15
That special variant of the Fradkin representation, previously defined for scalar Green`s functions {ital G}{sub {ital c}}({ital x},{ital y}{vert_bar}{ital A}) in an arbitrary potential {ital A}({ital z}), is here extended to the case of vector interactions and spinor Green`s functions of QED and QCD. An exact representation is given which may again be approximated by a finite number {ital N} of quadratures, with the order of magnitude of the errors generated specified in advance, and decreasing with increasing {ital N}. A feature appears for both exact and approximate {ital G}{sub {ital c}}[{ital A}]: the possibility of chaotic behavior of a function central to the representation, which in turn generates chaotic behavior in {ital G}{sub {ital c}}[{ital A}] for certain {ital A}({ital z}). An example is given to show how the general criterion specified here works for a known case of ``quantum chaos,`` in a potential theory context of first quantization. When the full, nonperturbative, radiative corrections of quantum field theory are included, such chaotic effects are removed.
Progress in vacuum susceptibilities and their applications to the chiral phase transition of QCD
Cui, Zhu-Fang; Hou, Feng-Yao; Shi, Yuan-Mei; Wang, Yong-Long; Zong, Hong-Shi
2015-07-15
The QCD vacuum condensates and various vacuum susceptibilities are all important parameters which characterize the nonperturbative properties of the QCD vacuum. In the QCD sum rules external field formula, various QCD vacuum susceptibilities play important roles in determining the properties of hadrons. In this paper, we review the recent progress in studies of vacuum susceptibilities together with their applications to the chiral phase transition of QCD. The results of the tensor, the vector, the axial–vector, the scalar, and the pseudo-scalar vacuum susceptibilities are shown in detail in the framework of Dyson–Schwinger equations.
Testing QCD in the non-perturbative regime
A.W. Thomas
2007-01-01
This is an exciting time for strong interaction physics. We have a candidate for a fundamental theory, namely QCD, which has passed all the tests thrown at it in the perturbative regime. In the non-perturbative regime it has also produced some promising results and recently a few triumphs but the next decade will see enormous progress in our ability to unambiguously calculate the consequences of non-perturbative QCD and to test those predictions experimentally. Amongst the new experimental facilities being constructed, the hadronic machines at JPARC and GSI-FAIR and the 12 GeV Upgrade at Jefferson Lab, the major new electromagnetic facility worldwide, present a beautifully complementary network aimed at producing precise new measurements which will advance our knowledge of nuclear systems and push our ability to calculate the consequences of QCD to the limit. We will first outline the plans at Jefferson Lab for doubling the energy of CEBAF. The new facility presents some wonderful opportunities for discovery in strong interaction physics, as well as beyond the standard model. Then we turn to the theoretical developments aimed at extracting precise results for physical hadron properties from lattice QCD simulations. This discussion will begin with classical examples, such as the mass of the nucleon and ?, before dealing with a very recent and spectacular success involving information extracted from modern parity violating electron scattering.
Pfeiffer, P.; Egusquiza, I. L.; Di Ventra, M.; Sanz, M.; Solano, E.
2016-07-06
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantummore » regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. As a result, the proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.« less
Quantum chaos in compact lattice QED
Berg, B.A. [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States); [Supercomputer Computations Research Institute, The Florida State University, Tallahassee, Florida 32306 (United States); Markum, H. [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria)] [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria); Pullirsch, R. [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States); [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria)
1999-05-01
Complete eigenvalue spectra of the staggered Dirac operator in quenched 4D compact QED are studied on 8{sup 3}{times}4 and 8{sup 3}{times}6 lattices. We investigate the behavior of the nearest-neighbor spacing distribution P(s) as a measure of the fluctuation properties of the eigenvalues in the strong coupling and the Coulomb phase. In both phases we find agreement with the Wigner surmise of the unitary ensemble of random-matrix theory indicating quantum chaos. Combining this with previous results on QCD, we conjecture that quite generally the non-linear couplings of quantum field theories lead to a chaotic behavior of the eigenvalues of the Dirac operator. {copyright} {ital 1999} {ital The American Physical Society}
Results on QCD Physics from the CDF-II Experiment
Pagliarone, C.; /Cassino U. /INFN, Pisa
2006-12-01
In this paper the authors review a selection of recent results obtained, in the area of QCD physics, from the CDF-II experiment that studies p{bar p} collisions at {radical}s = 1.96 TeV provided by the Fermilab Tevatron Collider. All results shown correspond to analysis performed using the Tevatron Run II data samples. In particular they will illustrate the progress achieved and the status of the studies on the following QCD processes: jet inclusive production, using different jet clustering algorithm, W({yields} e{nu}{sub e}) + jets and Z({yields} e{sup +}e{sup -}) + jets production, {gamma} + b-jet production, dijet production in double pomeron exchange and finally exclusive e{sup +}e{sup -} and {gamma}{gamma} production. No deviations from the Standard Model have been observed so far.
QCD and strongly coupled gauge theories: Challenges and perspectives
Brambilla, N.; Eidelman, S.; Foka, P.; Gardner, S.; Kronfeld, A. S.; Alford, M. G.; Alkofer, R.; Butenschoen, M.; Cohen, T. D.; Erdmenger, J.; Fabbietti, L.; Faber, M.; Goity, J. L.; Ketzer, B.; Lin, H. W.; Llanes-Estrada, F. J.; Meyer, H. B.; Pakhlov, P.; Pallante, E.; Polikarpov, M. I.; Sazdjian, H.; Schmitt, A.; Snow, W. M.; Vairo, A.; Vogt, R.; Vuorinen, A.; Wittig, H.; Arnold, P.; Christakoglou, P.; Di Nezza, P.; Fodor, Z.; Garcia i Tormo, X.; Höllwieser, R.; Janik, M. A.; Kalweit, A.; Keane, D.; Kiritsis, E.; Mischke, A.; Mizuk, R.; Odyniec, G.; Papadodimas, K.; Pich, A.; Pittau, R.; Qiu, J. -W.; Ricciardi, G.; Salgado, C. A.; Schwenzer, K.; Stefanis, N. G.; von Hippel, G. M.; Zakharov, V. I.
2014-10-21
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to stongly-coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.
More on the renormalization group limit cycle in QCD
Evgeny Epelbaum; Hans-Werner Hammer; Ulf-G. Meissner; Andreas Nogga
2006-02-26
We present a detailed study of the recently conjectured infrared renormalization group limit cycle in QCD using chiral effective field theory. We show that small increases in the up and down quark masses, corresponding to a pion mass around 200 MeV, can move QCD to the critical renormalization group trajectory for an infrared limit cycle in the three-nucleon system. At the critical values of the quark masses, the binding energies of the deuteron and its spin-singlet partner are tuned to zero and the triton has infinitely many excited states with an accumulation point at the three-nucleon threshold. At next-to-leading order in the chiral counting, we find three parameter sets where this effect occurs. For one of them, we study the structure of the three-nucleon system using both chiral and contact effective field theories in detail. Furthermore, we calculate the influence of the limit cycle on scattering observables.
QCD and strongly coupled gauge theories: Challenges and perspectives
Brambilla, N.; Eidelman, S.; Foka, P.; Gardner, S.; Kronfeld, A. S.; Alford, M. G.; Alkofer, R.; Butenschoen, M.; Cohen, T. D.; Erdmenger, J.; et al
2014-10-21
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to stongly-coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many researchmore » streams which flow into and out of QCD, as well as a vision for future developments.« less
Report of the 2005 Snowmass Top/QCD Working Group
Juste, A.; Kiyo, Y.; Petriello, F.; Teubner, T.; Agashe, K.; Batra, P.; Baur, U.; Berger, C.F.; Cembranos, J.A.R.; Gehrmann-De Ridder, A.; Gehrmann, T.; Glover, E.W.N.; Godfrey, S.; Hoang, A.; Perelstein, M.; Sullivan, Z.; Tait, T.; Zhu, S.; /Johns Hopkins U. /Princeton, Inst. Advanced Study /Syracuse U. /Argonne /SUNY, Buffalo /SLAC /UC, Irvine /Zurich, ETH /Zurich U. /Durham U., IPPP /Ottawa Carleton Inst. Phys. /Munich, Max Planck Inst. /Cornell U., CIHEP /Peking U.
2006-01-17
This report discusses several topics in both top quark physics and QCD at an International Linear Collider (ILC). Issues such as measurements at the t tbar threshold, including both theoretical and machine requirements, and the determination of electroweak top quark couplings are reviewed. New results concerning the potential of a 500 GeV e+e collider for measuring Wtb couplings and the top quark Yukawa coupling are presented. The status of higher order QCD corrections to jet production cross sections, heavy quark form factors, and longitudinal gauge boson scattering, needed for percent-level studies at the ILC, are reviewed. A new study of the measurement of the hadronic structure of the photon at a gamma gamma collider is presented. The effects on top quark properties from several models of new physics, including composite models, Little Higgs theories, and CPT violation, are studied.
Spontaneous supersymmetry breaking in two dimensional lattice super QCD
Catterall, Simon; Veernala, Aarti
2015-10-02
We report on a non-perturbative study of two dimensional N=(2,2) super QCD. Our lattice formulation retains a single exact supersymmetry at non-zero lattice spacing, and contains Nf fermions in the fundamental representation of a U(Nc) gauge group. The lattice action we employ contains an additional Fayet-Iliopoulos term which is also invariant under the exact lattice supersymmetry. This work constitutes the first numerical study of this theory which serves as a toy model for understanding some of the issues that are expected to arise in four dimensional super QCD. As a result, we present evidence that the exact supersymmetry breaks spontaneouslymore » when Nf < Nc in agreement with theoretical expectations.« less
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)
Spontaneous supersymmetry breaking in two dimensional lattice super QCD
Catterall, Simon; Veernala, Aarti
2015-10-02
We report on a non-perturbative study of two dimensional N=(2,2) super QCD. Our lattice formulation retains a single exact supersymmetry at non-zero lattice spacing, and contains N_{f} fermions in the fundamental representation of a U(N_{c}) gauge group. The lattice action we employ contains an additional Fayet-Iliopoulos term which is also invariant under the exact lattice supersymmetry. This work constitutes the first numerical study of this theory which serves as a toy model for understanding some of the issues that are expected to arise in four dimensional super QCD. As a result, we present evidence that the exact supersymmetry breaks spontaneously when N_{f} < N_{c} in agreement with theoretical expectations.
High-Energy QCD Asymptotics of Photon--Photon Collisions
Brodsky, Stanley J.
2002-07-26
The high-energy behavior of the total cross section for highly virtual photons, as predicted by the BFKL equation at next-to-leading order (NLO) in QCD, is discussed. The NLO BFKL predictions, improved by the BLM optimal scale setting, are in good agreement with recent OPAL and L3 data at CERN LEP2. NLO BFKL predictions for future linear colliders are presented.
The nucleon axial charge in full lattice QCD
Robert Edwards; George Fleming; P Hagler; John Negele; Konstantinos Orginos; Andrew Pochinsky; Dru Renner; David Richards; Wolfram Schroers
2005-10-13
The nucleon axial charge is calculated as a function of the pion mass in full QCD. Using domain wall valence quarks and improved staggered sea quarks, we present the first calculation with pion masses as light as 354 MeV and volumes as large as (3.5 fm)3. We show that finite volume effects are small for our volumes and that a constrained fit based on finite volume chiral perturbation theory agrees with experiment within 5% statistical errors.
Muon g - 2 Hadronic Vacuum Polarization from Lattice QCD | Argonne
U.S. Department of Energy (DOE) all webpages (Extended Search)
Leadership Computing Facility Muon g - 2 Hadronic Vacuum Polarization from Lattice QCD PI Name: John Laiho PI Email: jwlaiho@syr.edu Institution: Syracuse University Allocation Program: ALCC Allocation Hours at ALCF: 66 Million Year: 2016 Research Domain: Physics The Standard Model of particle physics has been enormously successful in describing the sub--- atomic world of particle physics. A persistent exception to this success is the disagreement between the Standard Model prediction and
Heavy Quarks, QCD, and Effective Field Theory (Technical Report) | SciTech
Office of Scientific and Technical Information (OSTI)
Connect Heavy Quarks, QCD, and Effective Field Theory Citation Details In-Document Search Title: Heavy Quarks, QCD, and Effective Field Theory The research supported by this OJI award is in the area of heavy quark and quarkonium production, especially the application Soft-Collinear E ective Theory (SCET) to the hadronic production of quarkonia. SCET is an e ffective theory which allows one to derive factorization theorems and perform all order resummations for QCD processes. Factorization
Dissipative quantum computing with open quantum walks
Sinayskiy, Ilya; Petruccione, Francesco
2014-12-04
An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.
Four fermion operator matching with nonrelativistic QCD heavy and asqtad light quarks
Gamiz, Elvira; Shigemitsu, Junko; Trottier, Howard
2008-06-01
We present one-loop matching coefficients between continuum and lattice QCD for the heavy-light four-fermion operators relevant for neutral B meson mixing both within and beyond the standard model. For the lattice theory we use nonrelativistic QCD (NRQCD) to describe b quarks and improved staggered fermions (AsqTad) for light quarks. The gauge action is the tree-level Symanzik improved gauge action. Matching to full QCD is carried out through order {alpha}{sub s}, {lambda}{sub QCD}/M{sub b}, and {alpha}{sub s}/(aM{sub b})
A Framework for Lattice QCD Calculations on GPUs
Winter, Frank; Clark, M.A.; Edwards, Robert G.; Joo, Balint
2014-08-01
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.
Triangle Universities Nuclear Laboratory : 2011
U.S. Department of Energy (DOE) all webpages (Extended Search)
Mohammad Ahmed Haiyan Gao Henry Weller Publications INSPIRES List Useful Links HIGS TUNL Medium Energy Group Structure of the Hadron Electromagnetic reactions on light nuclei, such as Compton scattering on proton, deuteron, and 3He targets, provide a unique oppertunity to perform stringent tests of the predictions 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 this
U.S. Department of Energy (DOE) all webpages (Extended Search)
MILC MILC Description The benchmark code MILC represents part of a set of codes written by the MIMD Lattice Computation (MILC) collaboratoration used to study quantum chromodynamics (QCD), the theory of the strong interactions of subatomic physics. It performs simulations of four dimensional SU(3) lattice gauge theory on MIMD parallel machines. "Strong interactions" are responsible for binding quarks into protons and neutrons and holding them all together in the atomic nucleus. The
Pion Form Factor in Improved Holographic QCD Backgrounds
Kwee, Herry J.
2010-08-05
We extend our recent numerical calculation of the pion electromagnetic form factor F{sub {pi}}(Q{sup 2}) in holographic QCD with a background field that interpolates between 'hard-wall' and 'soft-wall' models to obtain an improved model that reproduces the desirable phenomenological features of both. In all cases, F{sub {pi}}for large Q{sup 2} is shallower than data, an effect that can be cured by relaxing the fit to one of the static observables, particularly the decay constant f{sub {pi}}.
The Brief Life of a Hadron: QCD unquenched
Pennington, Michael R.
2015-03-01
Once upon a time, the picture of hadrons was of mesons made of a quark and an antiquark, and baryons of three quarks. Though hadrons heavier than the ground states inevitably decay by the strong interaction, the successes of the quark model might suggest their decays are a mere perturbation. However, Eef van Beveren, whose career we celebrate here, recognised that decays are an integral part of the life of a hadron. The channels into which they decay are often essential to their very existence. These hold the secrets of strong coupling QCD and teach us the way quarks really build hadrons.
beta. -Decay in the Skyrme-Witten representation of QCD
Snyderman, N.J.
1991-05-01
The renormalized coupling strength of the {beta}-decay axial vector current is related to {pi}{plus minus} p cross sections through the Adler-Weisberger sum rule, that follows from chiral symmetry. We attempt to understand the Adler-Weisberger sum rule in the 1/N{sub c} expansion in QCD, and in the Skyrme-Witten model that realizes the 1/N{sub c} expansion in the low energy limit, using it to explicitly calculate both g{sub A} and the {pi}{plus minus} p cross sections. 32 refs.
Spectroscopy of triply charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2014-10-14
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. As a result, 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.
Evidence for a bound H-dibaryon using lattice QCD
Will Detmold
2012-04-01
The H-dibaryon, a J = 0 state with the valence quark content udsuds, has long been hypothesized to exist because of the attractive nature of color magnetic gluon exchange in the flavor- singlet channel. Using lattice QCD the NPLQCD collaboration have investigated this system and evidence is presented for the existence of a stable H-dibaryon, albeit at a quark mass somewhat larger than that in nature. This calculation is reviewed and combined with subsequent calculations by the HALQCD collaboration at the SU(3) flavor symmetric point to identify bounds on the H-dibaryon mass at the physical quark masses.
Quarkonium-nucleus bound states from lattice QCD
Beane, S. R.; Chang, E.; Cohen, S. D.; Detmold, W.; Lin, H. -W.; Orginos, K.; Parreño, A.; Savage, M. J.
2015-06-11
Quarkonium-nucleus systems are composed of two interacting hadronic states without common valence quarks, which interact primarily through multi-gluon exchanges, realizing a color van der Waals force. We present lattice QCD calculations of the interactions of strange and charm quarkonia with light nuclei. Both the strangeonium-nucleus and charmonium-nucleus systems are found to be relatively deeply bound when the masses of the three light quarks are set equal to that of the physical strange quark. Extrapolation of these results to the physical light-quark masses suggests that the binding energy of charmonium to nuclear matter is B < 40 MeV.
NLO QCD corrections to ZZ jet production at hadron colliders
Binoth, T.; Gleisberg, T.; Karg, S.; Kauer, N.; Sanguinetti, G.
2010-05-26
A fully differential calculation of the next-to-leading order QCD corrections to the production of Z-boson pairs in association with a hard jet at the Tevatron and LHC is presented. This process is an important background for Higgs particle and new physics searches at hadron colliders. We find sizable corrections for cross sections and differential distributions, particularly at the LHC. Residual scale uncertainties are typically at the 10% level and can be further reduced by applying a veto against the emission of a second hard jet. Our results confirm that NLO corrections do not simply rescale LO predictions.
Regularization scheme independence and unitarity in QCD cross sections
Catani, S.; Seymour, M.H.; Trocsanyi, Z.
1997-06-01
When calculating next-to-leading order QCD cross sections, divergences in intermediate steps of the calculation must be regularized. The final result is independent of the regularization scheme used, provided that it is unitary. In this paper we explore the relationship between regularization scheme independence and unitarity. We show how the regularization scheme dependence can be isolated in simple universal components, and how unitarity can be guaranteed for any regularization prescription that can consistently be introduced in one-loop amplitudes. Finally, we show how to derive transition rules between different schemes without having to do any loop calculations. {copyright} {ital 1997} {ital The American Physical Society}
Viscous quark-gluon plasma model through fluid QCD approach
Djun, T. P.; Soegijono, B.; Mart, T.; Handoko, L. T. E-mail: Laksana.tri.handoko@lipi.go.id
2014-09-25
A Lagrangian density for viscous quark-gluon plasma has been constructed within the fluid-like QCD framework. Gauge symmetry is preserved for all terms inside the Lagrangian, except for the viscous term. The transition mechanism from point particle field to fluid field, and vice versa, are discussed. The energy momentum tensor that is relevant to the gluonic plasma having the nature of fluid bulk of gluon sea is derived within the model. By imposing conservation law in the energy momentum tensor, shear viscosity appears as extractable from the equation.
Nonperturbative dynamics in the color-magnetic QCD vacuum
Nefediev, A. V. Simonov, Yu. A.
2008-01-15
In the deconfinement phase of QCD, quarks and gluons interact with the dense stochastic color-magnetic vacuum. We consider the dynamics of quarks in this deconfinement phase using the field correlators method and derive an effective nonperturbative interquark potential, in addition to the usual perturbative short-range interaction. We find the resulting angular-momentum-dependent interaction to be attractive enough to maintain bound states and, for light quarks (and gluons), to cause emission of quark and gluon pairs. Possible consequences for the strong-interacting quark-gluon plasma are briefly discussed.
Spectroscopy of triply charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2014-10-01
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.
Duality Quantum Information and Duality Quantum Communication
Li, C. Y.; Wang, W. Y.; Wang, C.; Song, S. Y.; Long, G. L.
2011-03-28
Quantum mechanical systems exhibit particle wave duality property. This duality property has been exploited for information processing. A duality quantum computer is a quantum computer on the move and passing through a multi-slits. It offers quantum wave divider and quantum wave combiner operations in addition to those allowed in an ordinary quantum computer. It has been shown that all linear bounded operators can be realized in a duality quantum computer, and a duality quantum computer with n qubits and d-slits can be realized in an ordinary quantum computer with n qubits and a qudit in the so-called duality quantum computing mode. The quantum particle-wave duality can be used in providing secure communication. In this paper, we will review duality quantum computing and duality quantum key distribution.
Vector and scalar charmonium resonances with lattice QCD
Lang, C. B.; Leskovec, Luka; Mohler, Daniel; Prelovsek, Sasa
2015-09-15
We perform an exploratory lattice QCD simulation of DD¯ scattering, aimed at determining the masses as well as the decay widths of charmonium resonances above open charm threshold. Neglecting coupling to other channels, the resulting phase shift for DD¯scattering in p-wave yields the well-known vector resonance ψ(3770). For m _{π} = 156 MeV, the extracted resonance mass and the decay width agree with experiment within large statistical uncertainty. The scalar charmonium resonances present a puzzle, since only the ground state χ _{c0}(1P ) is well understood, while there is no commonly accepted candidate for its first excitation. We then simulate DD¯scattering in s-wave in order to shed light on this puzzle. The resulting phase shift supports the existence of a yet-unobserved narrow resonance with a mass slightly below 4 GeV. A scenario with this narrow resonance and a pole at χ _{c0}(1P), we found, agrees with the energy-dependence of our phase shift. Further lattice QCD simulations and experimental efforts are needed to resolve the puzzle of the excited scalar charmonia.
Dynamics near QCD critical point by dynamic renormalization group
Minami, Yuki
2011-05-01
We work out the basic analysis on dynamics near the QCD critical point (CP) by the dynamic renormalization group (RG). In addition to the RG analysis by coarse-graining, we construct the nonlinear Langevin equation as a basic equation for the critical dynamics. Our construction is based on the generalized Langevin theory and the relativistic hydrodynamics. Applying the dynamic RG to the constructed equation, we derive the RG equation for the transport coefficients and analyze their critical behaviors. We find that the resulting RG equation turns out to be the same as that for the liquid-gas CP except for an insignificant constant. Therefore, the bulk viscosity and the thermal conductivity strongly diverge at the QCD CP. We also show that the thermal and viscous diffusion modes exhibit critical slowing down with the dynamic critical exponents z{sub thermal}{approx}3 and z{sub viscous}{approx}2, respectively. In contrast, the sound propagating mode shows critical speeding up with the negative exponent z{sub sound}{approx}-0.8.
Vector and scalar charmonium resonances with lattice QCD
Lang, C. B.; Leskovec, Luka; Mohler, Daniel; Prelovsek, Sasa
2015-09-15
We perform an exploratory lattice QCD simulation of DD scattering, aimed at determining the masses as well as the decay widths of charmonium resonances above open charm threshold. Neglecting coupling to other channels, the resulting phase shift for DD scattering in p-wave yields the well-known vector resonance ?(3770). For m? = 156 MeV, the extracted resonance mass and the decay width agree with experiment within large statistical uncertainty. The scalar charmonium resonances present a puzzle, since only the ground state ?c0(1P) is well understood, while there is no commonly accepted candidate for its first excitation. We simulate DD scattering inmores-wave in order to shed light on this puzzle. The resulting phase shift supports the existence of a yet-unobserved narrow resonance with a mass slightly below 4 GeV. A scenario with this narrow resonance and a pole at ?c0(1P) agrees with the energy-dependence of our phase shift. In addition, further lattice QCD simulations and experimental efforts are needed to resolve the puzzle of the excited scalar charmonia.less
Bootstrapping Multi-Parton Loop Amplitudes in QCD
Bern, Zvi; Dixon, Lance J.; Kosower, David A.; /Saclay, SPhT
2005-07-06
The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.
Vector and scalar charmonium resonances with lattice QCD
Lang, C. B.; Leskovec, Luka; Mohler, Daniel; Prelovsek, Sasa
2015-09-15
We perform an exploratory lattice QCD simulation of DD¯ scattering, aimed at determining the masses as well as the decay widths of charmonium resonances above open charm threshold. Neglecting coupling to other channels, the resulting phase shift for DD¯scattering in p-wave yields the well-known vector resonance ψ(3770). For m π = 156 MeV, the extracted resonance mass and the decay width agree with experiment within large statistical uncertainty. The scalar charmonium resonances present a puzzle, since only the ground state χ c0(1P ) is well understood, while there is no commonly accepted candidate for its first excitation. We then simulatemore » DD¯scattering in s-wave in order to shed light on this puzzle. The resulting phase shift supports the existence of a yet-unobserved narrow resonance with a mass slightly below 4 GeV. A scenario with this narrow resonance and a pole at χ c0(1P), we found, agrees with the energy-dependence of our phase shift. Further lattice QCD simulations and experimental efforts are needed to resolve the puzzle of the excited scalar charmonia.« less
Method to study complex systems of mesons in lattice QCD
Detmold, William; Savage, Martin J.
2010-07-30
Correlation functions involving many hadrons allow finite density systems to be explored with Lattice QCD. Recently, systems with up to 12more » $$\\pi^+$$'s or $K^+$'s have been studied to determine the the $3$-$$\\pi^+$$ and $3$-$K^+$ interactions and the corresponding chemical potential has been determined as a function of density in each case. We derive recursion relations between correlation functions that allow us to extend this work to systems of arbitrary numbers of mesons and to systems containing arbitrary different types of mesons such as $$\\pi^+$$'s, $K^+$'s, $D^0$'s and $B^+$'s. These relations allow for the study of finite-density systems in arbitrary volumes, and the study of high-density systems. Systems comprised of up to N=12 m mesons can be explored with Lattice QCD calculations utilizing $m$ different sources for the quark propagators. As the recursion relations require only a small, N-independent, number of operations to derive the N+1 meson contractions from the N meson contractions, they are compuationally feasible.« less
Improved methods for the study of hadronic physics from lattice QCD
Orginos, Kostas; Richards, David
2015-02-05
The solution of QCD on a lattice provides a first-principles method for understanding QCD in the low-energy regime, and is thus an essential tool for nuclear physics. The generation of gauge configurations, the starting point for lattice calculations, requires the most powerful leadership-class computers available. However, to fully exploit such leadership-class computing requires increasingly sophisticated methods for obtaining physics observables from the underlying gauge ensembles. In this study, we describe a variety of recent methods that have been used to advance our understanding of the spectrum and structure of hadrons through lattice QCD.
Lincoln, Don
2014-10-24
The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isnt empty at all its a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs quantum foam. In this video, Fermilabs Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.
The 3D structure of the hadrons: recents results and experimental program at Jefferson Lab
Munoz Camacho, Carlos
2014-04-01
The understanding of Quantum Chromodynamics (QCD) at large distances still remains one of the main outstanding problems of nuclear physics. Studying the internal structure of hadrons provides a way to probe QCD in the non-perturbative domain and can help us unravel the internal structure of the most elementary blocks of matter. Jefferson Lab (JLab) has already delivered results on how elementary quarks and gluons create nucleon structure and properties. The upgrade of JLab to 12 GeV will allow the full exploration of the valence-quark structure of nucleons and the extraction of real threedimensional pictures. I will present recent results and review the future experimental program at JLab.
Study of hadronic event-shape variables in multijet final states in pp collisions at √s = 7 TeV
Khachatryan, V.
2014-10-14
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 are selected with at least one jet with transverse momentum pT > 110 GeV and pseudorapidity |η| < 2.4, in a data sample corresponding to integrated luminosities of up to 5 fb–1. As a result, the distributions of five event-shape variables in various leading jet pT ranges are compared to predictions from different QCD Monte Carlo event generators.
Study of the D*? system using QCD sum rules
Torres, A. Martnez; Khemchandani, K. P.; Nielsen, M.; Navarra, F. S.; Oset, E.
2014-11-11
In this proceeding we present a study of the D*? system made by using the method of QCD sum rules. Considering isospin and spin projectors, we investigate the different configurations and obtain three D* mesons with isospin I = 1/2, spin S = 0, 1, 2 and with masses 250067 MeV, 252360 MeV, and 2439119 MeV, respectively. The last state can be related to D{sub 2}{sup *} (2460) (spin 2) listed by the Particle Data Group, while one of the first two might be associated with D*(2640), whose spin-parity is unknown. In the case of I = 3/2 we also find evidences of three states with spin 0, 1 and 2, respectively, with masses 246782 MeV, 2420128 MeV, and 255056 MeV.
Novel QCD Effects from Initial and Final State Interactions
Brodsky, Stanley J.
2007-09-12
Initial-state and final-state interactions which are conventionally neglected in the parton model, have a profound effect in QCD hard-scattering reactions. The effects, which arise from gluon exchange between the active and spectator quarks, cause leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and the breakdown of the Lam-Tung relation in Drell-Yan reactions. Diffractive deep inelastic scattering also leads to nuclear shadowing and non-universal antishadowing of nuclear structure functions through multiple scattering reactions in the nuclear target. Factorization-breaking effects are particularly important for hard hadron interactions since both initial-state and final-state interactions appear. Related factorization breaking effects can also appear in exclusive electroproduction reactions and in deeply virtual Compton scattering. None of the effects of initial-state and final-state interactions are incorporated in the light-front wavefunctions of the target hadron computed in isolation.
Toward the excited isoscalar meson spectrum from lattice QCD
Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; Thomas, Christopher E.
2013-11-18
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 J^{PC} channels; one notable exception is the pseudoscalar sector where the approximate SU(3)_{F} octet, singlet structure of the η, η' is reproduced. We extract exotic J^{PC} 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 qq¯-like spectrum.
Transverse momentum-dependent parton distribution functions in lattice QCD
Engelhardt, Michael G. [New Mexico State University; Musch, Bernhard U. [Tech. University Munich; Haegler, Philipp G. [Tech. University Munich; Negele, John W. [MIT; Schaefer, Andreas [Regensburg
2013-08-01
A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.
Toward the excited isoscalar meson spectrum from lattice QCD
Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; Thomas, Christopher E.
2013-11-18
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 η, η' is reproduced. We extract exotic JPC states, identifiedmore » 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 qq¯-like spectrum.« less
Highly Excited Baryons in Large-Nc QCD
Matagne, N.; Stancu, Fl.
2005-06-14
We use the 1/Nc expansion of QCD to analyse the spectrum of positive parity resonances with strangeness S = 0, -1, -2 and -3 in the 2-3 GeV mass region, supposed to belong to the [56,4+] multiplet. The mass operator is similar to that of [56,2+], previously studied in the literature. The analysis of the latter is revisited. In the [56,4+] multiplet we find that the spin-spin term brings the dominant contribution and that the spin-orbit term is entirely negligible in the hyperfine interaction, in agreement with the constituent quark model practice, where this interaction is usually neglected. More data are strongly desirable, especially in the strange sector in order to fully exploit the power of this approach. We discuss possibilities of extending the calculations to other excited baryons belonging to the N = 2 or the N = 4 band.
Evidence for a Bound H Dibaryon from Lattice QCD
Beane, S. R.; Chang, E.; Parreno, A.; Detmold, W.; Orginos, K.; Joo, B.; Lin, H. W.; Savage, M. J.; Luu, T. C.; Torok, A.; Walker-Loud, A.
2011-04-22
We present evidence for the existence of a bound H dibaryon, an I=0, J=0, s=-2 state with valence quark structure uuddss, at a pion mass of m{sub {pi}{approx}3}89 MeV. Using the results of lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of L{approx}2.0, 2.5, 3.0, and 3.9 fm at a spatial lattice spacing of b{sub s{approx}}0.123 fm, we find an H dibaryon bound by B{sub {infinity}}{sup H}=16.6{+-}2.1{+-}4.6 MeV at a pion mass of m{sub {pi}{approx}3}89 MeV.
Infrared singularities of scattering amplitudes in perturbative QCD
Becher, Thomas; Neubert, Matthias
2013-11-01
An exact formula is derived for the infrared singularities of dimensionally regularized scattering amplitudes in massless QCD with an arbitrary number of legs, valid at any number of loops. It is based on the conjecture that the anomalous-dimension matrix of n-jet operators in soft-collinear effective theory contains only a single non-trivial color structure, whose coefficient is the cusp anomalous dimension of Wilson loops with light-like segments. Its color-diagonal part is characterized by two anomalous dimensions, which are extracted to three-loop order from known perturbative results for the quark and gluon form factors. This allows us to predict the three-loop coefficients of all 1/epsilon^k poles for an arbitrary n-parton scattering amplitudes, generalizing existing two-loop results.
Bulk viscosity of anisotropically expanding hot QCD plasma
Chandra, Vinod
2011-11-01
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.
Antiangular Ordering of Gluon Radiation in QCD Media
Mehtar-Tani, Yacine; Salgado, Carlos A.; Tywoniuk, Konrad
2011-03-25
We investigate angular and energy distributions of medium-induced gluon emission off a quark-antiquark antenna in the framework of perturbative QCD as an attempt toward understanding, from first principles, jet evolution inside the quark-gluon plasma. In-medium color coherence between emitters, neglected in all previous calculations, leads to a novel mechanism of soft-gluon radiation. The structure of the corresponding spectrum, in contrast with known medium-induced radiation, i.e., off a single emitter, retains some properties of the vacuum case; in particular, it exhibits a soft divergence. However, as opposed to the vacuum, the collinear singularity is regulated by the pair opening angle, leading to a strict angular separation between vacuum and medium-induced radiation, denoted as antiangular ordering. We comment on the possible consequences of this new contribution for jet observables in heavy-ion collisions.
Role of the nonperturbative input in QCD resummed Drell-Yan Q...
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Collins-Soper-Sterman (CSS) b-space QCD resummation formalism for Drell-Yan transverse momentum (Qsub T) distributions, and investigate the predictive power of the CSS formalism. ...
Fundamental Properties of QCD Matter produced at RHIC and the LHC | Argonne
U.S. Department of Energy (DOE) all webpages (Extended Search)
Leadership Computing Facility The image illustrates how protons, neutrons, and other hadrons formed from quarks and gluons during the QCD transition as the universe expanded The image illustrates how protons, neutrons, and other hadrons formed from quarks and gluons during the QCD transition as the universe expanded. Since the transition is a crossover, there is no sharp temperature, only a broad range where the transition happened. Sandor Katz, Eotvos University, Budapest, Hungary
RECENT LATTICE RESULTS ON FINITE TEMPERATURE AND DENSITY QCD, PART 1.
KARSCH,F.
2007-07-09
We discuss recent progress made studies of bulk thermodynamics of strongly interacting matter through lattice simulations of QCD with an almost physical light and strange quark mass spectrum. We present results on the QCD equation of state at vanishing and non-vanishing quark chemical potential and show first results on baryon number and strangeness fluctuations, which might be measured in event-by-event fluctuations in low energy runs at RHIC as well as at FAIR.
Quantum simulations of strongly coupled quark-gluon plasma
Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.
2011-09-15
A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the model developed by B.A. Gelman, E.V. Shuryak, and I. Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective string-like forces and turn out to be colorless. At the temperature as large as twice the critical one no bound states are observed. Quantum effects turned out to be of prime importance in these simulations.
Adiabatically implementing quantum gates
Sun, Jie; Lu, Songfeng Liu, Fang
2014-06-14
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.
Curvature of the freeze-out line in heavy ion collisions
Bazavov, A.; Ding, H. -T.; Hegde, P.; Kaczmarek, O.; Karsch, F.; Laermann, E.; Mukherjee, Swagato; Ohno, H.; Petreczky, P.; Schmidt, C.; et al
2016-01-28
Here, we calculate the mean and variance of net-baryon number and net-electric charge distributions from quantum chromodynamics (QCD) using a next-to-leading order Taylor expansion in terms of temperature and chemical potentials. Moreover, these expansions with experimental data from STAR and PHENIX are compared, we determine the freeze-out temperature in the limit of vanishing baryon chemical potential, and, for the first time, constrain the curvature of the freeze-out line through a direct comparison between experimental data on net-charge fluctuations and a QCD calculation. We obtain a bound on the curvature coefficient, κmore » $^f$$_2$<0.011, that is compatible with lattice QCD results on the curvature of the QCD transition line.« less
Stapp, Henry
2011-11-10
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
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Quantum computers have long been on the horizon as conventional computing technologies approach their physical limits. While general-purpose quantum computers remain on the horizon ...
Resonances in coupled ?K, ?K scattering from lattice QCD
Wilson, David J.; Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.
2015-03-10
Coupled-channel ?K and ?K scattering amplitudes are determined by studying the finite-volume energy spectra obtained from dynamical lattice QCD calculations. Using a large basis of interpolating operators, including both those resembling a qq-bar construction and those resembling a pair of mesons with relative momentum, a reliable excited-state spectrum can be obtained. Working at m? = 391 MeV, we find a gradual increase in the JP = 0+ ?K phase-shift which may be identified with a broad scalar resonance that couples strongly to ?K and weakly to ?K. The low-energy behavior of this amplitude suggests a virtual bound-state that may be related to the ? resonance. A bound state with JP = 1- is found very close to the ?K threshold energy, whose coupling to the ?K channel is compatible with that of the experimental K*(892). Evidence is found for a narrow resonance in JP = 2+. Isospin3/2 ?K scattering is also studied and non-resonant phase-shifts spanning the whole elastic scattering region are obtained.
Spectroscopy of doubly charmed baryons from lattice QCD
Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael
2015-05-06
This study presents the ground and excited state spectra of doubly charmed baryons from lattice QCD with dynamical quark fields. Calculations are performed on anisotropic lattices of size 16³ × 128, with inverse spacing in temporal direction a_{t}⁻¹=5.67(4) GeV and with a pion mass of about 390 MeV. A large set of baryonic operators that respect the symmetries of the lattice yet which retain a memory of their continuum analogues are used. These operators transform as irreducible representations of SU(3)_{F} symmetry for flavor, SU(4) symmetry for Dirac spins of quarks and O(3) for spatial symmetry. The distillation method is utilized to generate baryon correlation functions which are analyzed using the variational fitting method to extract excited states. The lattice spectra obtained have baryonic states with well-defined total spins up to 7/2 and the pattern of low-lying states does not support the diquark picture for doubly charmed baryons. On the contrary the calculated spectra are remarkably similar to the expectations from models with an SU(6)×O(3) symmetry. Various spin-dependent energy splittings between the extracted states are also evaluated.
Finite Volume Dependence of Hadron Properties and Lattice QCD
Anthony W. Thomas; Jonathan D. Ashley; Derek B. Leinweber; Ross D. Young
2005-02-01
Because the time needed for a simulation in lattice QCD varies at a rate exceeding the fourth power of the lattice size, it is important to understand how small one can make a lattice without altering the physics beyond recognition. It is common to use a rule of thumb that the pion mass times the lattice size should be greater than (ideally much greater than) four (i.e., m{sub {pi}} L >> 4). By considering a relatively simple chiral quark model we are led to suggest that a more realistic constraint would be m{sub {pi}} (L - 2R) >> 4, where R is the radius of the confinement region, which for these purposes could be taken to be around 0.8-1.0 fm. Within the model we demonstrate that violating the second condition can lead to unphysical behavior of hadronic properties as a function of pion mass. In particular, the axial charge of the nucleon is found to decrease quite rapidly as the chiral limit is approached.
Mass and Width of the Lowest Resonance in QCD
Caprini, I.; Colangelo, G.; Leutwyler, H.
2006-04-07
We demonstrate that near the threshold, the {pi}{pi} scattering amplitude contains a pole with the quantum numbers of the vacuum- commonly referred to as the {sigma} - and determine its mass and width within small uncertainties. Our derivation does not involve models or parametrizations but relies on a straightforward calculation based on the Roy equation for the isoscalar S wave.
One-loop calculations in quantum field theory: from Feynman diagrams to unitarity cuts
Ellis, R. Keith; Kunszt, Zoltan; Melnikov, Kirill; Zanderighi, Giulia
2012-09-01
The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques become inefficient. Recently new approaches based on unitarity have been developed for calculating one-loop scattering amplitudes in quantum field theory. These methods are especially suitable for the description of multi-particle processes in QCD and are amenable to numerical implementations. We present a systematic pedagogical description of both conceptual and technical aspects of the new methods.
High detectivity short-wavelength II-VI quantum cascade detector
Ravikumar, Arvind P. Gmachl, Claire F.; Garcia, Thor A.; Tamargo, Maria C.; Jesus, Joel De
2014-08-11
We report on the experimental demonstration of a ZnCdSe/ZnCdMgSe-based short-wavelength photovoltaic Quantum Cascade Detector (QCD). The QCD operates in two spectral bands centered around 2.6??m and 3.6??m. Calibrated blackbody measurements yield a peak responsivity of 0.1?mA/W or 2400?V/W at 80?K, and a corresponding 300?K background radiation limited infrared performance detectivity (BLIP) of ?2.5??10{sup 10?}cm ?Hz/W. Comparison of background illuminated and dark current-voltage measurements demonstrates a BLIP temperature of 200?K. The device differential resistance-area product, decreases from about 10{sup 6} ? cm{sup 2} at 80?K to about 8000 ? cm{sup 2} at 300?K, indicative of the ultra-low Johnson noise in the detectors.
Ab-Initio Hamiltonian Approach to Light Nuclei And to Quantum Field Theory
Vary, J.P.; Honkanen, H.; Li, Jun; Maris, P.; Shirokov, A.M.; Brodsky, S.J.; Harindranath, A.; de Teramond, G.F.; Ng, E.G.; Yang, C.; Sosonkina, M.; /Ames Lab
2012-06-22
Nuclear structure physics is on the threshold of confronting several long-standing problems such as the origin of shell structure from basic nucleon-nucleon and three-nucleon interactions. At the same time those interactions are being developed with increasing contact to QCD, the underlying theory of the strong interactions, using effective field theory. The motivation is clear - QCD offers the promise of great predictive power spanning phenomena on multiple scales from quarks and gluons to nuclear structure. However, new tools that involve non-perturbative methods are required to build bridges from one scale to the next. We present an overview of recent theoretical and computational progress with a Hamiltonian approach to build these bridges and provide illustrative results for the nuclear structure of light nuclei and quantum field theory.
Sigma meson in pole-dominated QCD sum rules
Kojo, Toru; Jido, Daisuke
2008-12-01
The properties of the {sigma} meson are studied using the QCD sum rules for tetraquark operators. In the SU(3) chiral limit, we separately investigate SU(3) singlet and octet tetraquark states as constituents of the {sigma} meson and discuss their roles for the classification of the light scalar nonets {sigma}, f{sub 0}, a{sub 0}, and {kappa} as candidates of tetraquark states. All of our analyses are performed in the suitable Borel window which is indispensable to avoid the pseudopeak artifacts outside of the Borel window. We can set up acceptably wide Borel windows after preparing favorable linear combinations of operators and including the dimension 12 terms in the operator-product expansion. Taking into account the possible large widths, we evaluate masses for singlet and octet states as 700-850 and 600-750 MeV, respectively, although the octet operators have a smaller overlap with the tetraquark states than the singlet case, which requires careful interpretations. The splitting of the singlet and octet states emerges from the number of the qq annihilation diagrams, which include the color singlet annihilation processes qqqq{yields}(qq){sub 1} and the color octet annihilation processes qqqq{yields}G(qq){sub 8}. The mass of the {sigma} meson is evaluated as 600-800 MeV, which is much closer to the experimental value {approx}500 MeV than the mass evaluated by 2-quark correlator analyses, {approx}1.0 GeV. This indicates that the tetraquark state shares a larger fraction in the {sigma} meson than ordinary two quark meson states.
Neutral B meson mixing in unquenched lattice QCD
Gamiz, Elvira; Davies, Christine T. H.; Lepage, G. Peter; Shigemitsu, Junko; Wingate, Matthew
2009-07-01
We study B{sub d} and B{sub s} mixing in unquenched lattice QCD employing the MILC Collaboration gauge configurations that include u, d, and s sea quarks based on the improved staggered quark (AsqTad) action and a highly improved gluon action. We implement the valence light quarks also with the AsqTad action and use the nonrelativistic NRQCD action for the valence b quark. We calculate hadronic matrix elements necessary for extracting Cabibbo-Kobayashi-Maskawa matrix elements from experimental measurements of mass differences {delta}M{sub d} and {delta}M{sub s}. We find {xi}{identical_to}f{sub B{sub s}}{radical}(B-circumflex{sub B{sub s}})/f{sub B{sub d}}{radical}(B-circumflex{sub B{sub d}})=1.258(33), f{sub B{sub d}}{radical}(B-circumflex{sub B{sub d}})=216(15) MeV, and f{sub B{sub s}}{radical}(B-circumflex{sub B{sub s}})=266(18) MeV. We also update previous results for decay constants and obtain f{sub B{sub d}}=190(13) MeV, f{sub B{sub s}}=231(15) MeV, and f{sub B{sub s}}/f{sub B{sub d}}=1.226(26). The new lattice results lead to updated values for the ratio of Cabibbo-Kobayashi-Maskawa matrix elements |V{sub td}|/|V{sub ts}| and for the standard model prediction for Br(B{sub s}{yields}{mu}{sup +}{mu}{sup -}) with reduced errors. We determine |V{sub td}|/|V{sub ts}|=0.214(1)(5) and Br(B{sub s}{yields}{mu}{sup +}{mu}{sup -})=3.19(19)x10{sup -9}.
Meson Transition Form Factors in Light-Front Holographic QCD
Brodsky, Stanley J.; Cao, Fu-Guang; de Teramond, Guy F.; /Costa Rica U.
2011-06-22
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 Chern-Simons action, which is a natural form in 5-dimensional anti-de Sitter (AdS) space, leads directly to an expression for the photon-to-pion TFF for a class of confining models. Remarkably, the predicted pion TFF is identical to the leading order QCD result where the distribution amplitude has asymptotic form. The Chern-Simons form is local in AdS space and is thus somewhat limited in its predictability. It only retains the q{bar q} component of the pion wavefunction, and further, it projects out only the asymptotic form of the meson distribution amplitude. It is found that in order to describe simultaneously the decay process {pi}{sup 0} {yields} {gamma}{gamma} and the pion TFF at the asymptotic limit, a probability for the q{bar q} component of the pion wavefunction P{sub q{bar q}} = 0.5 is required; thus giving indication that the contributions from higher Fock states in the pion light-front wavefunction need to be included in the analysis. The probability for the Fock state containing four quarks (anti-quarks) which follows from analyzing the hadron matrix elements, P{sub q{bar q}q{bar q}} {approx} 10%, agrees with the analysis of the pion elastic form factor using light-front holography including higher Fock components in the pion wavefunction. The results for the TFFs for the {eta} and {eta}{prime} mesons are also presented. The rapid growth of the pion TFF exhibited by the BABAR data at high Q{sup 2} is not compatible with the models discussed in this article, whereas the theoretical calculations are in agreement with the experimental data for the {eta} and {eta}{prime} TFFs.
How perfect can a gluon plasma be in perturbative QCD?
Chen, Jiunn-Wei; Deng Jian; Dong Hui; Wang Qun
2011-02-01
The shear viscosity to entropy density ratio, {eta}/s, characterizes how perfect a fluid is. We calculate the leading order {eta}/s of a gluon plasma in perturbation using the kinetic theory. The leading order contribution only involves the elastic gg{r_reversible}gg (22) process and the inelastic gg{r_reversible}ggg (23) process. The hard-thermal-loop (HTL) treatment is used for the 22 matrix element, while the exact matrix element in vacuum is supplemented by the gluon Debye mass insertion for the 23 process. Also, the asymptotic mass is used for the external gluons in the kinetic theory. The errors from not implementing HTL and the Landau-Pomeranchuk-Migdal effect in the 23 process, and from the uncalculated higher order corrections, are estimated. Our result smoothly connects the two different approximations used by Arnold, Moore, and Yaffe (AMY) and Xu and Greiner (XG). At small {alpha}{sub s} ({alpha}{sub s}<<1), our result is closer to AMY's collinear result while at larger {alpha}{sub s} the finite angle noncollinear configurations become more important and our result is closer to XG's soft bremsstrahlung result. In the region where perturbation is reliable ({alpha}{sub s} < or approx. 0.1), we find no indication that the proposed perfect fluid limit {eta}/s{approx_equal}1/(4{pi}) can be achieved by perturbative QCD alone. Whether this can be achieve for {alpha}{sub s} > or approx. 0.1 is still an open question.
Anomalous QCD contribution to the Debye screening in an external field via holography
Gorsky, A.; Kopnin, P. N.; Krikun, A.
2011-03-15
In this paper we discuss the QCD contribution to the Abelian Debye and magnetic screening masses in a deconfined QCD plasma at finite temperature in the presence of an external magnetic field B. We use a holographic AdS/QCD setup in an AdS Schwarzschild black hole background and show that the electric screening mass has a form similar to the one-loop result in QED. Moreover, we calculate the corrections due to the magnetic field to all orders of B and demonstrate that in the case when the magnetic field is large the Debye mass grows linearly with B, while the magnetic screening mass vanishes. The whole effect of the magnetic field turns out to stem from the Chern-Simons action. We also discuss the zero temperature case in the chiral perturbation theory.
Bridging a gap between continuum-QCD and ab initio predictions of hadron observables
Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis; Roberts, Craig D.
2015-01-23
Within contemporary hadron physics there are two common methods for determining the momentum-dependence of the interaction between quarks: the top-down approach, which works toward an ab initio computation of the interaction via direct analysis of the gauge-sector gap equations; and the bottom-up scheme, which aims to infer the interaction by fitting data within a well-defined truncation of those equations in the matter sector that are relevant to bound-state properties. We unite these two approaches by demonstrating that the renormalisation-group-invariant running-interaction predicted by contemporary analyses of QCDs gauge sector coincides with that required in order to describe ground-state hadron observables usingmorea nonperturbative truncation of QCDs DysonSchwinger equations in the matter sector. This bridges a gap that had lain between nonperturbative continuum-QCD and the ab initio prediction of bound-state properties.less
Present constraints on the H-dibaryon at the physical point from Lattice QCD
Beane, S. R.; Chang, E.; Detmold, W.; Joo, B.; Lin, H. -W.; Luu, T. C.; Orginos, K.; Parreno, A.; Savage, M. J.; Torok, A.; et al
2011-11-10
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 dependencemore » observed in Lattice QCD calculations of the octet baryon masses. In both cases, the extrapolation to the physical pion mass allows for a bound H-dibaryon or a near-threshold scattering state.« less
Scalable quantum computer architecture with coupled donor-quantum...
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Title: Scalable quantum computer architecture with coupled donor-quantum dot qubits A quantum bit computing architecture includes a plurality of single spin memory donor atoms ...
Quantum Fuel Systems Technologies Worldwide Inc Quantum Technologies...
Open Energy Information (Open El) [EERE & EIA]
Fuel Systems Technologies Worldwide Inc Quantum Technologies Jump to: navigation, search Name: Quantum Fuel Systems Technologies Worldwide Inc (Quantum Technologies) Place: Irvine,...
Two nucleon systems at ${m}_{\pi}~450\text{}\text{}\mathrm{MeV}$ from lattice QCD
Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Beane, Silas R.; Chang, Emmanuel; Detmold, William
2015-12-23
Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass of $m_\\pi\\sim 450~{\\rm MeV}$ in three spatial volumes using $n_f=2+1$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $B_d = 14.4^{+3.2}_{-2.6} ~{\\rm MeV}$, while the dineutron is bound by $B_{nn} = 12.5^{+3.0}_{-5.0}~{\\rm MeV}$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the 1S0 and 3S1-3D1 channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the effective range expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. Thus, the extracted phase shifts allow for matching to nuclear effective field theories, from which low energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann–Okubo mass relation.
SPIN Effects, QCD, and Jefferson Laboratory with 12 GeV electrons
Prokudin, Alexey
2013-11-01
QCD and Spin physics are playing important role in our understanding of hadron structure. I will give a short overview of origin of hadron structure in QCD and highlight modern understanding of the subject. Jefferson Laboratory is undergoing an upgrade that will increase the energy of electron beam up to 12 GeV. JLab is one of the leading facilities in nuclear physics studies and once operational in 2015 JLab 12 will be crucial for future of nuclear physics. I will briefly discuss future studies in four experimental halls of Jefferson Lab.
QCD CORRECTIONS TO DILEPTON PRODUCTION NEAR PARTONIC THRESHOLD IN PP SCATTERING.
SHIMIZU, H.; STERMAN, G.; VOGELSANG, W.; YOKOYA, H.
2005-10-02
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.
Matching next-to-leading order predictions to parton showers in supersymmetric QCD
Degrande, Céline; Fuks, Benjamin; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng
2016-02-03
We present a fully automated framework based on the FeynRules and MadGraph5_aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.
Reliable quantum communication over a quantum relay channel
Gyongyosi, Laszlo; Imre, Sandor
2014-12-04
We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.
Meson transition form factors in light-front holographic QCD
Brodsky, Stanley J.; Cao Fuguang; de Teramond, Guy F.
2011-10-01
We study the photon-to-meson transition form factors (TFFs) F{sub M}{gamma}(Q{sup 2}) for {gamma}{gamma}{sup *}{yields}M using light-front holographic methods. The Chern-Simons action, which is a natural form in five-dimensional anti-de Sitter (AdS) space, is required to describe the anomalous coupling of mesons to photons using holographic methods and leads directly to an expression for the photon-to-pion TFF for a class of confining models. Remarkably, the predicted pion TFF is identical to the leading order QCD result where the distribution amplitude has asymptotic form. The Chern-Simons form is local in AdS space and is thus somewhat limited in its predictability. It only retains the qq component of the pion wave function, and further, it projects out only the asymptotic form of the meson distribution amplitude. It is found that in order to describe simultaneously the decay process {pi}{sup 0}{yields}{gamma}{gamma} and the pion TFF at the asymptotic limit, a probability for the qq component of the pion wave function P{sub qq}=0.5 is required, thus giving indication that the contributions from higher Fock states in the pion light-front wave function need to be included in the analysis. The probability for the Fock state containing four quarks P{sub qqqq}{approx}10%, which follows from analyzing the hadron matrix elements for a dressed current model, agrees with the analysis of the pion elastic form factor using light-front holography including higher Fock components in the pion wave function. The results for the TFFs for the {eta} and {eta}{sup '} mesons are also presented. The rapid growth of the pion TFF exhibited by the BABAR data at high Q{sup 2} is not compatible with the models discussed in this article, whereas the theoretical calculations are in agreement with the experimental data for the {eta} and {eta}{sup '} TFFs.
Magnetic structure of light nuclei from lattice QCD
Chang, Emmanuel; Detmold, William; Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; Beane, Silas R.
2015-12-09
Lattice QCD with background magnetic fields is used to calculate the magnetic moments and magnetic polarizabilities of the nucleons and of light nuclei withmore » $$A\\le4$$, along with the cross-section for the $M1$ transition $$np\\rightarrow d\\gamma$$, at the flavor SU(3)-symmetric point where the pion mass is $$m_\\pi\\sim 806$$ MeV. These magnetic properties are extracted from nucleon and nuclear energies in six uniform magnetic fields of varying strengths. The magnetic moments are presented in a recent Letter. For the charged states, the extraction of the polarizability requires careful treatment of Landau levels, which enter non-trivially in the method that is employed. The nucleon polarizabilities are found to be of similar magnitude to their physical values, with $$\\beta_p=5.22(+0.66/-0.45)(0.23) \\times 10^{-4}$$ fm$^3$ and $$\\beta_n=1.253(+0.056/-0.067)(0.055) \\times 10^{-4}$$ fm$^3$, exhibiting a significant isovector component. The dineutron is bound at these heavy quark masses and its magnetic polarizability, $$\\beta_{nn}=1.872(+0.121/-0.113)(0.082) \\times 10^{-4}$$ fm$^3$ differs significantly from twice that of the neutron. A linear combination of deuteron scalar and tensor polarizabilities is determined by the energies of the $$j_z=\\pm 1$$ deuteron states, and is found to be $$\\beta_{d,\\pm 1}=4.4(+1.6/-1.5)(0.2) \\times 10^{-4}$$ fm$^3$. The magnetic polarizabilities of the three-nucleon and four-nucleon systems are found to be positive and similar in size to those of the proton, $$\\beta_{^{3}\\rm He}=5.4(+2.2/-2.1)(0.2) \\times 10^{-4}$$ fm$^3$, $$\\beta_{^{3}\\rm H}=2.6(1.7)(0.1) \\times 10^{-4}$$ fm$^3$, $$\\beta_{^{4}\\rm He}=3.4(+2.0/-1.9)(0.2) \\times 10^{-4}$$ fm$^3$. Mixing between the $j_z=0$ deuteron state and the spin-singlet $np$ state induced by the background magnetic field is used to extract the short-distance two-nucleon counterterm, $${\\bar L}_1$$, of the pionless effective theory for $NN$ systems (equivalent to the
Magnetic structure of light nuclei from lattice QCD
Chang, Emmanuel; Detmold, William; Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; Beane, Silas R.
2015-12-09
Lattice QCD with background magnetic fields is used to calculate the magnetic moments and magnetic polarizabilities of the nucleons and of light nuclei with $A\\le4$, along with the cross-section for the $M1$ transition $np\\rightarrow d\\gamma$, at the flavor SU(3)-symmetric point where the pion mass is $m_\\pi\\sim 806$ MeV. These magnetic properties are extracted from nucleon and nuclear energies in six uniform magnetic fields of varying strengths. The magnetic moments are presented in a recent Letter. For the charged states, the extraction of the polarizability requires careful treatment of Landau levels, which enter non-trivially in the method that is employed. The nucleon polarizabilities are found to be of similar magnitude to their physical values, with $\\beta_p=5.22(+0.66/-0.45)(0.23) \\times 10^{-4}$ fm$^3$ and $\\beta_n=1.253(+0.056/-0.067)(0.055) \\times 10^{-4}$ fm$^3$, exhibiting a significant isovector component. The dineutron is bound at these heavy quark masses and its magnetic polarizability, $\\beta_{nn}=1.872(+0.121/-0.113)(0.082) \\times 10^{-4}$ fm$^3$ differs significantly from twice that of the neutron. A linear combination of deuteron scalar and tensor polarizabilities is determined by the energies of the $j_z=\\pm 1$ deuteron states, and is found to be $\\beta_{d,\\pm 1}=4.4(+1.6/-1.5)(0.2) \\times 10^{-4}$ fm$^3$. The magnetic polarizabilities of the three-nucleon and four-nucleon systems are found to be positive and similar in size to those of the proton, $\\beta_{^{3}\\rm He}=5.4(+2.2/-2.1)(0.2) \\times 10^{-4}$ fm$^3$, $\\beta_{^{3}\\rm H}=2.6(1.7)(0.1) \\times 10^{-4}$ fm$^3$, $\\beta_{^{4}\\rm He}=3.4(+2.0/-1.9)(0.2) \\times 10^{-4}$ fm$^3$. Mixing between the $j_z=0$ deuteron state and the spin-singlet $np$ state induced by the background magnetic field is used to extract the short-distance two-nucleon counterterm, ${\\bar L}_1$, of the pionless effective theory for $NN$ systems (equivalent to the meson-exchange current
Quantum optics. Gravity meets quantum physics
Adams, Bernhard W.
2015-02-27
Albert Einstein’s general theory of relativity is a classical formulation but a quantum mechanical description of gravitational forces is needed, not only to investigate the coupling of classical and quantum systems but simply to give a more complete description of our physical surroundings. In this issue of Nature Photonics, Wen-Te Liao and Sven Ahrens reveal a link between quantum and gravitational physics. They propose that in the quantum-optical effect of superradiance, the world line of electromagnetic radiation is changed by the presence of a gravitational field.
QCD For Intel(R) Xeon Phi(tm) and Xeon(tm) processors
Energy Science and Technology Software Center (OSTI)
2014-09-11
This library provides a library containing highly optimized Wilson-Dslash, Wilson Clover operator and Krylov subspace solvers for Lattice QCD simulations. The library is targeted at Intel(R) Xeon Phi(tm), and Intel(R) Xeon(tm) processors.
Lattice QCD Thermodynamics : 10k analysis with 1k thermalziation and block size of 500.
Soltz, R; Vranas, P; Gupta, R
2007-05-10
This is a re-analysis of the Lattice QCD Thermodynamics p4rhcm new beta analysis (UCRL-TR-230742) with approximately 10k trajectories per beta point, rerun with thermalization cut at 1000, and a block size of 500. Some diagnostic text has been omitted to reduce the number of pages.
Unitary Structure of the QCD Sum Rules and KYN and KY{xi} Couplings
Aliev, T.; Ozpineci, A.; Yakovlev, S. B.; Zamiralov, V. S.
2006-01-12
New relations between QCD Borel sum rules for strong coupling constants of K-mesons to baryons are derived. It is shown that starting from the sum rule for the coupling constants g{pi}{sigma}{sigma} and g{pi}{sigma}{lambda} it is straightforward to obtain corresponding sum rules for the gKYN, gKY{xi} couplings, Y = {sigma}, {lambda}.
Drell-Yan Lepton pair production at NNLO QCD with parton showers
Hoeche, Stefan; Li, Ye; Prestel, Stefan
2015-04-13
We present a simple approach to combine NNLO QCD calculations and parton showers, based on the UNLOPS technique. We apply the method to the computation of Drell-Yan lepton-pair production at the Large Hadron Collider. We comment on possible improvements and intrinsic uncertainties.
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ANNIHILATION; FLAVOR MODEL; SUPERNOVAE; QUANTUM CHROMODYNAMICS; HEAVY ION REACTIONS; SUN; NUCLEAR THEORY; CONVERSION; CHARM PARTICLES; PROGRESS REPORT; NONLUMINOUS MATTER; STAR...
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Research in theoretical nuclear and neutrino physics. Final report
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Setting the Renormalization Scale in QCD: The Principle of Maximum Conformality
Brodsky, Stanley J.; Di Giustino, Leonardo; /SLAC
2011-08-19
A key problem in making precise perturbative QCD predictions is the uncertainty in determining the renormalization scale {mu} of the running coupling {alpha}{sub s}({mu}{sup 2}): The purpose of the running coupling in any gauge theory is to sum all terms involving the {beta} function; in fact, when the renormalization scale is set properly, all non-conformal {beta} {ne} 0 terms in a perturbative expansion arising from renormalization are summed into the running coupling. The remaining terms in the perturbative series are then identical to that of a conformal theory; i.e., the corresponding theory with {beta} = 0. The resulting scale-fixed predictions using the 'principle of maximum conformality' (PMC) are independent of the choice of renormalization scheme - a key requirement of renormalization group invariance. The results avoid renormalon resummation and agree with QED scale-setting in the Abelian limit. The PMC is also the theoretical principle underlying the BLM procedure, commensurate scale relations between observables, and the scale-setting method used in lattice gauge theory. The number of active flavors nf in the QCD {beta} function is also correctly determined. We discuss several methods for determining the PMC/BLM scale for QCD processes. We show that a single global PMC scale, valid at leading order, can be derived from basic properties of the perturbative QCD cross section. The elimination of the renormalization scheme ambiguity using the PMC will not only increase the precision of QCD tests, but it will also increase the sensitivity of collider experiments to new physics beyond the Standard Model.
U.S. Department of Energy (DOE) all webpages (Extended Search)
Quantum ESPRESSO/PWscf Quantum ESPRESSO/PWscf Description Quantum ESPRESSO is an integrated suite of computer codes for electronic structure calculations and materials modeling at the nanoscale. It builds on the electronic structure codes PWscf, PHONON, CP90, FPMD, and Wannier. It is based on density-functional theory, plane waves, and pseudopotentials (both norm-conserving and ultrasoft). How to Access Quantum ESPRESSO NERSC uses modules to manage access to software. To use the default version
Huang, Liang; Lai Yingcheng; Ferry, David K.; Goodnick, Stephen M.; Akis, Richard
2009-07-31
The concentrations of wave functions about classical periodic orbits, or quantum scars, are a fundamental phenomenon in physics. An open question is whether scarring can occur in relativistic quantum systems. To address this question, we investigate confinements made of graphene whose classical dynamics are chaotic and find unequivocal evidence of relativistic quantum scars. The scarred states can lead to strong conductance fluctuations in the corresponding open quantum dots via the mechanism of resonant transmission.
Scalable optical quantum computer
Manykin, E A; Mel'nichenko, E V [Institute for Superconductivity and Solid-State Physics, Russian Research Centre 'Kurchatov Institute', Moscow (Russian Federation)
2014-12-31
A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr{sup 3+}, regularly located in the lattice of the orthosilicate (Y{sub 2}SiO{sub 5}) crystal, are suggested to be used as optical qubits. Operations with qubits are performed using coherent and incoherent laser pulses. The operation protocol includes both the method of measurement-based quantum computations and the technique of optical computations. Modern hybrid photon echo protocols, which provide a sufficient quantum efficiency when reading recorded states, are considered as most promising for quantum computations and communications. (quantum computer)
Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara
MILC asqtad QCD SU(3) gauge ensemble; series=a; a=0.11fm minus 0.0022fm ; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)
Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050b
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara
MILC asqtad QCD SU(3) gauge ensemble; series=b; a=0.11fm minus 0.0022fm; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)
Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050b
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara
2015-01-01
MILC asqtad QCD SU(3) gauge ensemble; series=b; a=0.11fm minus 0.0022fm; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)
Lattice QCD gauge ensemble: USQCD/MILC/asqtad/2064f21b678m010m050
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Aubin, Christopher Alan [Fordham U.; Bernard, Claude W. [Washington U. St. Louis; Burch, Tommy [U. Regensburg; Datta, Saumen [Tata Institute; DeGrand, Thomas Alan [Colorado U., Boulder; DeTar, Carleton E. [Utah U.; Gottlieb, Steven A. [Indiana U., Bloomington; Gregory, Eric Brittain [Wuppertal U.; Heller, Urs M. [American Physical Society; Hetrick, James Edward [U. Pacific, Stockton; Orginos, Kostas Nikolaou [William-Mary Coll.; Osborn, James C. [Argonne National Laboratory, ALCF; Toussaint, W. Doug [Arizona U.; Sugar, Robert L. [U. C., Santa Barbara
2015-01-01
MILC asqtad QCD SU(3) gauge ensemble; series=a; a=0.11fm minus 0.0022fm ; Ls=2.16fm; Nf=2+1; u0.m0=(0.010,0.050)
The Nc dependencies of baryon masses: Analysis with Lattice QCD and Effective Theory
Calle Cordon, Alvaro C.; DeGrand, Thomas A.; Goity, Jose L.
2014-07-01
Baryon masses at varying values of Nc and light quark masses are studied with Lattice QCD and the results are analyzed in a low energy effective theory based on a combined framework of the 1/Nc and Heavy Baryon Chiral Perturbation Theory expansions. Lattice QCD results for Nc=3, 5 and 7 obtained in quenched calculations, as well as results for unquenched calculations for Nc=3, are used for the analysis. The results are consistent with a previous analysis of Nc=3 LQCD results, and in addition permit the determination of sub-leading in 1/Nc effects in the spin-flavor singlet component of the baryon masses as well as in the hyperfine splittings.
Exotic tetraquark udss of J{sup P}=0{sup +} in the QCD sum rule
Chen Huaxing; Hosaka, Atsushi; Zhu Shilin
2006-09-01
We study a QCD sum rule analysis for an exotic tetraquark udss of J{sup P}=0{sup +} and I=1. We construct qqqq currents in a local product form and find that there are five independent currents for this channel. Because of the high dimensional nature of the current, it is not easy to form a good sum rule when using a single current. This means that we do not find any sum rule window to extract reliable results, due to the insufficient convergence of the operator product expansion and to the exceptional important role of QCD continuum. Then we examine sum rules by using currents of linear combinations of two currents among the independent ones. We find two reasonable cases that predict a mass of the tetraquark around 1.5 GeV.
Predictions for diphoton production at the LHC through NNLO in QCD
Campbell, John M.; Ellis, R. Keith; Li, Ye; Williams, Ciaran
2016-07-29
In this paper we present a next-to-next-to-leading order (NNLO) calculation of the processmore » $$pp\\rightarrow \\gamma\\gamma$$ that we have implemented into the parton level Monte Carlo code MCFM. We do not find agreement with the previous calculation of this process in the literature. In addition to the $$\\mathcal{O}(\\alpha_s^2)$$ corrections present at NNLO, we include some effects arising at $$\\mathcal{O}(\\alpha_s^3)$$, namely those associated with gluon-initiated closed fermion loops. We investigate the role of this process in the context of studies of QCD at colliders and as a background for searches for new physics, paying particular attention to the diphoton invariant mass spectrum. We demonstrate that the NNLO QCD prediction for the shape of this spectrum agrees well with functional forms used in recent data-driven fits.« less
Superconformal Baryon-Meson Symmetry and Light-Front Holographic QCD
Dosch, Hans Guenter; de Teramond, Guy F.; Brodsky, Stanley J.
2015-04-10
We construct an effective QCD light-front Hamiltonian for both mesons and baryons in the chiral limit based on the generalized supercharges of a superconformal graded algebra. The superconformal construction is shown to be equivalent to a semi-classical approximation to light-front QCD and its embedding in AdS space. The specific breaking of conformal invariance inside the graded algebra uniquely determines the effective confinement potential. The generalized supercharges connect the baryon and meson spectra to each other in a remarkable manner. In particular, the π/b1 Regge trajectory is identified as the superpartner of the nucleon trajectory. However, the lowest-lying state on thismore » trajectory, the π-meson is massless in the chiral limit and has no supersymmetric partner.« less
An exact, finite, gauge-invariant, non-perturbative approach to QCD renormalization
Fried, H.M.; Tsang, P.H.; Gabellini, Y.; Grandou, T.; Sheu, Y.-M.
2015-08-15
A particular choice of renormalization, within the simplifications provided by the non-perturbative property of Effective Locality, leads to a completely finite, non-perturbative approach to renormalized QCD, in which all correlation functions can, in principle, be defined and calculated. In this Model of renormalization, only the Bundle chain-Graphs of the cluster expansion are non-zero. All Bundle graphs connecting to closed quark loops of whatever complexity, and attached to a single quark line, provided no ‘self-energy’ to that quark line, and hence no effective renormalization. However, the exchange of momentum between one quark line and another, involves only the cluster-expansion’s chain graphs, and yields a set of contributions which can be summed and provide a finite color-charge renormalization that can be incorporated into all other QCD processes. An application to High Energy elastic pp scattering is now underway.
Charged-Higgs-boson production at the LHC: Next-to-leading-order supersymmetric QCD corrections
Dittmaier, Stefan; Kraemer, Michael; Spira, Michael; Walser, Manuel
2011-03-01
The dominant production process for heavy charged-Higgs bosons at the LHC is the associated production with heavy quarks. We have calculated the next-to-leading-order supersymmetric QCD corrections to charged-Higgs production through the parton processes qq,gg{yields}tbH{sup {+-}} and present results for total cross sections and differential distributions. The QCD corrections reduce the renormalization and factorization scale dependence and thus stabilize the theoretical predictions. We present a comparison of the next-to-leading-order results for the inclusive cross section with a calculation based on bottom-gluon fusion gb{yields}tH{sup {+-}} and discuss the impact of the next-to-leading-order corrections on charged-Higgs searches at the LHC.
Strong coupling constants of heavy baryons with light mesons in QCD
Aliev, T. M.; Azizi, K.; Savci, M.
2012-10-23
The strong coupling constants of the heavy spin-1/2 and spin-3/2 baryons with light pseudoscalar and vector mesons are calculated in the framework of the light cone QCD sum rules. Using the symmetry arguments, some structure independent relations among different correlation functions are obtained. It is shown that all possible transitions are described by only one invariant function, whose explicit expression is structure dependent.
Magnetic moments of vector, axial, and tensor mesons in lattice QCD
Lee, Frank X.; Moerschbacher, Scott; Wilcox, Walter
2008-11-01
We present a calculation of magnetic moments for selected spin-1 mesons using the techniques of lattice QCD. This is carried out by introducing a 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{sup 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.
The Excited-state Spectrum of QCD through Lattice Gauge Theory Calculations
David Richards
2012-12-01
I describe recent progress at understanding the excited state spectrum of QCD through lattice gauge calculations. I begin by outlining the evolution of the lattice effort at JLab. I detail the impact of recent lattice calculations on the present and upcoming experimental programs, and in particular that of the 12 GeV upgrade of Jefferson Laboratory. I conclude with the prospect for future calculations.
Heavy-quarkonium interaction and the temperature dependence of the QCD static potential
Arleo, Francois
2005-06-14
We explore the temperature dependence of the heavy-quarkonium interaction based on the Bhanot-Peskin leading order perturbative QCD analysis. The Wilson coefficients are computed solving the Schroedinger equation in a screened Coulomb heavy-quark potential. The inverse Mellin transform of the Wilson coefficients then allows for the computation of the 1S and 2S heavy-quarkonium gluon and pion total cross section at finite screening.
QCD Sum Rules for Magnetically Induced Mixing between ηc and J/ψ
Cho, Sungtae; Hattori, Koichi; Lee, Su Houng; Morita, Kenji; Ozaki, Sho
2014-10-20
We investigate the properties of charmonia in strong magnetic fields by using QCD sum rules. We show how to implement the mixing effects between ηc and J/ψ on the basis of field-theoretical approaches, and then show that the sum rules are saturated by the mixing effects with phenomenologically determined parameters. Consequently, we find that the mixing effects are the dominant contribution to the mass shifts of the static charmonia in strong magnetic fields.
Massive photons: An infrared regularization scheme for lattice QCD+QED
Endres, Michael G.; Shindler, Andrea; Tiburzi, Brian C.; Walker-Loud, Andre
2016-08-10
The commonly adopted approach for including electromagnetic interactions in lattice QCD simulations relies on using finite volume as the infrared regularization for QED. The long-range nature of the electromagnetic interaction, however, implies that physical quantities are susceptible to power-law finite volume corrections, which must be removed by performing costly simulations at multiple lattice volumes, followed by an extrapolation to the infinite volume limit. In this work, we introduce a photon mass as an alternative means for gaining control over infrared effects associated with electromagnetic interactions. We present findings for hadron mass shifts due to electromagnetic interactions (i.e., for the proton,more » neutron, charged and neutral kaon) and corresponding mass splittings, and compare the results with those obtained from conventional QCD+QED calculations. Results are reported for numerical studies of three flavor electroquenched QCD using ensembles corresponding to 800 MeV pions, ensuring that the only appreciable volume corrections arise from QED effects. The calculations are performed with three lattice volumes with spatial extents ranging from 3.4 - 6.7 fm. As a result, we find that for equal computing time (not including the generation of the lattice configurations), the electromagnetic mass shifts can be extracted from computations on a single (our smallest) lattice volume with comparable or better precision than the conventional approach.« less
Nachtmann, O.
2014-11-15
We review ideas on the structure of the QCD vacuum which had served as motivation for the discussion of various non-standard QCD effects in high-energy reactions in articles from 1984 to 1995. These effects include, in particular, transverse-momentum and spin correlations in the Drell–Yan process and soft photon production in hadron–hadron collisions. We discuss the relation of the approach introduced in the above-mentioned articles to the approach, developed later, using transverse-momentum-dependent parton distributions (TDMs). The latter approach is a special case of our more general one which allows for parton entanglement in high-energy reactions. We discuss signatures of parton entanglement in the Drell–Yan reaction. Also for Higgs-boson production in pp collisions via gluon–gluon annihilation effects of entanglement of the two gluons are discussed and are found to be potentially important. These effects can be looked for in the current LHC experiments. In our opinion studying parton-entanglement effects in high-energy reactions is, on the one hand, very worthwhile by itself and, on the other hand, it allows to perform quantitative tests of standard factorisation assumptions. Clearly, the experimental observation of parton-entanglement effects in the Drell–Yan reaction and/or in Higgs-boson production would have a great impact on our understanding how QCD works in high-energy collisions.
$$B\\to Kl^+l^-$$ decay form factors from three-flavor lattice QCD
Bailey, Jon A.
2016-01-27
We compute the form factors for the B → Kl+l- semileptonic decay process in lattice QCD using gauge-field ensembles with 2+1 flavors of sea quark, generated by the MILC Collaboration. The ensembles span lattice spacings from 0.12 to 0.045 fm and have multiple sea-quark masses to help control the chiral extrapolation. The asqtad improved staggered action is used for the light valence and sea quarks, and the clover action with the Fermilab interpretation is used for the heavy b quark. We present results for the form factors f+(q2), f0(q2), and fT(q2), where q2 is the momentum transfer, together with a comprehensivemore » examination of systematic errors. Lattice QCD determines the form factors for a limited range of q2, and we use the model-independent z expansion to cover the whole kinematically allowed range. We present our final form-factor results as coefficients of the z expansion and the correlations between them, where the errors on the coefficients include statistical and all systematic uncertainties. Lastly, we use this complete description of the form factors to test QCD predictions of the form factors at high and low q2.« less
Brodsky, Stanley J.; /SLAC
2014-10-03
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.
Relating quantum discord with the quantum dense coding capacity
Wang, Xin; Qiu, Liang Li, Song; Zhang, Chi; Ye, Bin
2015-01-15
We establish the relations between quantum discord and the quantum dense coding capacity in (n + 1)-particle quantum states. A necessary condition for the vanishing discord monogamy score is given. We also find that the loss of quantum dense coding capacity due to decoherence is bounded below by the sum of quantum discord. When these results are restricted to three-particle quantum states, some complementarity relations are obtained.
Quantum dense key distribution
Degiovanni, I.P.; Ruo Berchera, I.; Castelletto, S.; Rastello, M.L.; Bovino, F.A.; Colla, A.M.; Castagnoli, G.
2004-03-01
This paper proposes a protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than the Bennet-Brassard 1984 protocol. We hereinafter prove the security of this scheme against individual eavesdropping attacks, and we present preliminary experimental results, showing its feasibility.
Audenaert, Koenraad M. R.
2014-11-15
In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
Teaney, Derek
2015-03-17
We review the results of the DE-FG02-08ER41540, "Establishing the transport properties of QCD with heavy ion reactions"
'Giant' Nanocrystal Quantum Dots
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Heller, E.J. (Los Alamos National Lab., Albuquerque, NM); Davis, M.J.
1982-06-10
This paper reviews some of the opinions on quantum chaos put forth at the 1981 American Conference on Theoretical Chemistry and presents evidence to support the author's point of view. The degree of correspondence between classical and quantum onset and extent of chaos differs markedly according to the definition adopted for quantum chaos. At one extreme, a quantum generalization of the classical Kolmolgorov entropy which give zero entrophy for quantum systems with a discrete spectrum regardless of the classical properties, was a suitable foundation for the definition of quantum chaos. At the other, the quantum phase space definition shows generally excellent correspondence to the classical phase space measures. The authors preferred this approach. Another point of controversy is the question of whether the spectrum of energy levels (or its variation with some parameter of the Hamiltonian) is enough to characterize the quantum chaos (or lack of it), or whether more information is needed (i.e., eigenfunctions). The authors conclude that one does not want to rely upon eigenvalues alone to characterize the degree of chaos in the quantum dynamics.
Efficient self-consistent quantum transport simulator for quantum...
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Journal Article: Efficient self-consistent quantum transport simulator for quantum ... DOE Contract Number: DE-AC04-94AL85000 Resource Type: Journal Article Resource Relation: ...
A new approach to analytic, non-perturbative and gauge-invariant QCD
Fried, H.M.; Grandou, T.; Sheu, Y.-M.
2012-11-15
Following a previous calculation of quark scattering in eikonal approximation, this paper presents a new, analytic and rigorous approach to the calculation of QCD phenomena. In this formulation a basic distinction between the conventional 'idealistic' description of QCD and a more 'realistic' description is brought into focus by a non-perturbative, gauge-invariant evaluation of the Schwinger solution for the QCD generating functional in terms of the exact Fradkin representations of Green's functional G{sub c}(x,y|A) and the vacuum functional L[A]. Because quarks exist asymptotically only in bound states, their transverse coordinates can never be measured with arbitrary precision; the non-perturbative neglect of this statement leads to obstructions that are easily corrected by invoking in the basic Lagrangian a probability amplitude which describes such transverse imprecision. The second result of this non-perturbative analysis is the appearance of a new and simplifying output called 'Effective Locality', in which the interactions between quarks by the exchange of a 'gluon bundle'-which 'bundle' contains an infinite number of gluons, including cubic and quartic gluon interactions-display an exact locality property that reduces the several functional integrals of the formulation down to a set of ordinary integrals. It should be emphasized that 'non-perturbative' here refers to the effective summation of all gluons between a pair of quark lines-which may be the same quark line, as in a self-energy graph-but does not (yet) include a summation over all closed-quark loops which are tied by gluon-bundle exchange to the rest of the 'Bundle Diagram'. As an example of the power of these methods we offer as a first analytic calculation the quark-antiquark binding potential of a pion, and the corresponding three-quark binding potential of a nucleon, obtained in a simple way from relevant eikonal scattering approximations. A second calculation, analytic, non-perturbative and
Ghenam, L.; Djoudi, A. Ait El
2012-06-27
We study the finite size and finite mass effects for the thermal deconfinement phase transition in Quantum Chromodynamics (QCD), using a simple model of coexistence of hadronic (H) gas and quark-gluon plasma (QGP) phases in a finite volume. We consider the equations of state of the two phases with the QGP containing two massless u and d quarks and massive s quarks, and a hadronic gas of massive pions, and we probe the system near the transition. For this, we examine the behavior of the most important hydrodynamical quantities describing the system, at a vanishing chemical potential ({mu}= 0), with temperature and energy density.
Two-photon physics as a probe of hadron dynamics
Brodsky, S.J.
1981-05-01
Two-photon collisions provide an ideal laboratory for testing many features of quantum chromodynamics, especially the interplay between the vector-meson-dominated and point-like hadronic interactions of the photon. A number of QCD applications are discussed, including: jet and single-particle production at large transverse momentum; the photon structure function and its relationship to the ..gamma.. ..-->.. q anti q wave function; and the possible role of gluonium states in the ..gamma gamma.. ..-->.. rho/sup 0/rho/sup 0/ channel. Evidence that even low momentum transfer photon-hadron interactions are sensitive to the point-like ..gamma.. ..-->.. q anti q coupling is discussed.
Measurement-only topological quantum computation via anyonic...
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Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANYONS; HALL EFFECT; INTERFEROMETRY; QUANTUM COMPUTERS; QUANTUM MECHANICS; QUANTUM TELEPORTATION; TOPOLOGY; ...
Quantum physics and human values
Stapp, H.P.
1989-09-01
This report discusses the following concepts: the quantum conception of nature; the quantum conception of man; and the impact upon human values. (LSP).
Vukmirovic, Nenad; Wang, Lin-Wang
2009-11-10
This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.
Fan, Wenjiang; Lawrie, Benjamin J.; Pooser, Raphael C.
2015-11-04
Surface plasmon resonance (SPR) sensors can reach the quantum noise limit of the optical readout field in various configurations. We demonstrate that two-mode intensity squeezed states produce a further enhancement in sensitivity compared with a classical optical readout when the quantum noise is used to transduce an SPR sensor signal in the Kretschmann configuration. The quantum noise reduction between the twin beams when incident at an angle away from the plasmonic resonance, combined with quantum noise resulting from quantum anticorrelations when on resonance, results in an effective SPR-mediated modulation that yields a measured sensitivity 5 dB better than that withmore » a classical optical readout in this configuration. Furthermore, the theoretical potential of this technique points to resolving particle concentrations with more accuracy than is possible via classical approaches to optical transduction.« less
Quantum random number generation
Ma, Xiongfeng; Yuan, Xiao; Cao, Zhu; Zhang, Zhen; Qi, Bing
2016-06-28
Here, quantum physics can be exploited to generate true random numbers, which play important roles in many applications, especially in cryptography. Genuine randomness from the measurement of a quantum system reveals the inherent nature of quantumness -- coherence, an important feature that differentiates quantum mechanics from classical physics. The generation of genuine randomness is generally considered impossible with only classical means. Based on the degree of trustworthiness on devices, quantum random number generators (QRNGs) can be grouped into three categories. The first category, practical QRNG, is built on fully trusted and calibrated devices and typically can generate randomness at amore » high speed by properly modeling the devices. The second category is self-testing QRNG, where verifiable randomness can be generated without trusting the actual implementation. The third category, semi-self-testing QRNG, is an intermediate category which provides a tradeoff between the trustworthiness on the device and the random number generation speed.« less
Toward quantum plasmonic networks
Holtfrerich, M. W.; Dowran, M.; Davidson, R.; Lawrie, B. J.; Pooser, R. C.; Marino, A. M.
2016-08-30
Here, we demonstrate the transduction of macroscopic quantum entanglement by independent, distant plasmonic structures embedded in separate thin silver films. In particular, we show that the plasmon-mediated transmission through each film conserves spatially dependent, entangled quantum images, opening the door for the implementation of parallel quantum protocols, super-resolution imaging, and quantum plasmonic sensing geometries at the nanoscale level. The conservation of quantum information by the transduction process shows that continuous variable multi-mode entanglement is momentarily transferred from entangled beams of light to the space-like separated, completely independent plasmonic structures, thus providing a first important step toward establishing a multichannel quantummore » network across separate solid-state substrates.« less
Fan, Wenjiang; Lawrie, Benjamin J.; Pooser, Raphael C.
2015-11-04
Surface plasmon resonance (SPR) sensors can reach the quantum noise limit of the optical readout field in various configurations. We demonstrate that two-mode intensity squeezed states produce a further enhancement in sensitivity compared with a classical optical readout when the quantum noise is used to transduce an SPR sensor signal in the Kretschmann configuration. The quantum noise reduction between the twin beams when incident at an angle away from the plasmonic resonance, combined with quantum noise resulting from quantum anticorrelations when on resonance, results in an effective SPR-mediated modulation that yields a measured sensitivity 5 dB better than that with a classical optical readout in this configuration. Furthermore, the theoretical potential of this technique points to resolving particle concentrations with more accuracy than is possible via classical approaches to optical transduction.
Quantum discord with weak measurements
Singh, Uttam Pati, Arun Kumar
2014-04-15
Weak measurements cause small change to quantum states, thereby opening up the possibility of new ways of manipulating and controlling quantum systems. We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the super quantum discord, is always larger than the quantum discord captured by the strong measurement. Moreover, we prove the monotonicity of the super quantum discord as a function of the measurement strength and in the limit of strong projective measurement the super quantum discord becomes the normal quantum discord. We find that unlike the normal discord, for pure entangled states, the super quantum discord can exceed the quantum entanglement. Our results provide new insights on the nature of quantum correlation and suggest that the notion of quantum correlation is not only observer dependent but also depends on how weakly one perturbs the composite system. We illustrate the key results for pure as well as mixed entangled states. -- Highlights: Introduced the role of weak measurements in quantifying quantum correlation. We have introduced the notion of the super quantum discord (SQD). For pure entangled state, we show that the SQD exceeds the entanglement entropy. This shows that quantum correlation depends not only on observer but also on measurement strength.
TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...
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Dan Stewart Iain W PHYSICS OF ELEMENTARY PARTICLES AND FIELDS CLASSICAL AND QUANTUM MECHANICS GENERAL PHYSICS FORM FACTORS GLUONS LAGRANGIAN FUNCTION QUANTUM CHROMODYNAMICS...
decays Bauer, Christian W.; Fleming, Sean; Pirjol, Dan; Stewart...
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Iain W. 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; FORM FACTORS; GLUONS; LAGRANGIAN FUNCTION; QUANTUM CHROMODYNAMICS;...
Nuclear Forces and High-Performance Computing: The Perfect Match...
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DOE Contract Number: W-7405-ENG-48 Resource Type: Conference ... ELEMENTARY PARTICLES AND FIELDS; GLUONS; NUCLEAR FORCES; NUCLEAR PHYSICS; QUANTUM CHROMODYNAMICS; QUANTUM FIELD THEORY...
In-medium hadron modification and meson spectroscopy
Chaden Djalali, Dennis Weygand
2010-04-01
The theory of the strong interaction, Quantum Chromodynamics (QCD), has been remarkably successful in describing high-energy and short-distance-scale experiments involving quarks and gluons. However, applying QCD to low energy and large-distance-scale experiments has been a major challenge. At low energies, standard nuclear physics with nucleon and meson degrees of freedom work effectively in describing observations. The transition between the two descriptions of hadrons is one of the main goals of hadronic physics. Lattice QCD calculations have made tremendous progress and will one day give us a full description of strong interactions under all regimes. Meanwhile, effective theories incorporating some of the main features of QCD have been successfully developed and help us gain insight into the non-perturbative regime of QCD. All these models predict modifications of the properties of hadrons embedded in nuclear matter. Mesons with exotic quantum numbers are predicted at excitation energies below 2 GeV. Several experiments have been conducted with the Cebaf Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Laboratory (JLab) to test these predictions.
Quantum histories without contrary inferences
Losada, Marcelo; Laura, Roberto
2014-12-15
In the consistent histories formulation of quantum theory it was shown that it is possible to retrodict contrary properties. We show that this problem do not appear in our formalism of generalized contexts for quantum histories. - Highlights: We prove ordinary quantum mechanics has no contrary properties. Contrary properties in consistent histories are reviewed. We prove generalized contexts for quantum histories have no contrary properties.
Axial current generation by P-odd domains in QCD matter
Iatrakis, Ioannis; Yin, Yi; Lin, Shu
2015-06-23
The dynamics of topological domains which break parity (P) and charge-parity (CP) symmetry of QCD are studied. We derive in a general setting that those local domains will generate an axial current and quantify the strength of the induced axial current. Thus, our findings are verified in a top-down holographic model. The relation between the real time dynamics of those local domains and the chiral magnetic field is also elucidated. We finally argue that such an induced axial current would be phenomenologically important in a heavy-ion collisions experiment.
Leading order hadronic contribution to g-2 from twisted mass QCD
Dru B Renner, Xu Feng, Karl Jansen, Marcus Petschlies
2010-06-01
We calculate the leading order hadronic contribution to the muon anomalous magnetic moment using twisted mass lattice QCD. The pion masses range from 330 MeV to 650 MeV. We use two lattice spacings, a=0.079 fm and 0.063 fm, to study lattice artifacts. Finite-size effects are studied for two values of the pion mass, and we calculate the disconnected contributions for four ensembles. Particular attention is paid to the dominant contributions of the vector mesons, both phenomenologically and from our lattice calculation.
Mixings of four-quark components in light nonsinglet scalar mesons in QCD sum rules
Sugiyama, J.; Nakamura, T.; Nishikawa, T.; Oka, M.; Ishii, N.
2007-12-01
Mixings of four-quark components in the nonsinglet scalar mesons are studied in the QCD sum rules. We propose a formulation to evaluate the cross correlators of qq and qqqq operators and to define the mixings of different Fock states in the sum rule. It is applied to the nonsinglet scalar mesons, a{sub 0} and K{sub 0}*. It is found that the four-quark operators predict lower masses than the qq operators and that the four-quark states occupy about 70%-90% of the lowest mass states.
QCD analysis of $W$- and $Z$-boson production at Tevatron
Camarda, S.; Belov, P.; Cooper-Sarkar, A. M.; Diaconu, C.; Glazov, A.; Guffanti, A.; Jung, A.; Kolesnikov, V.; Lohwasser, K.; Myronenko, V.; et al
2015-09-28
Recent measurements of the W-boson charge asymmetry and of the Z-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied using the HERAFitter framework to assess their impact on the proton parton distribution functions (PDFs). Thus, the Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the d-valence quark distribution.
Higgs boson gluon-fusion production beyond threshold in NLO QCD
Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard
2015-03-01
In this article, we compute the gluon fusion Higgs boson cross-section at NLO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full NLO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at NLO in perturbative QCD.
Higgs boson gluon-fusion production beyond threshold in N3LO QCD
Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard
2015-03-18
In this study, we compute the gluon fusion Higgs boson cross-section at N3LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N3LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N3LO in perturbative QCD.
DZero (D0) Experiment Results for QCD Physics from the Fermilab Tevatron
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
The D0 (DZero) Experiment is a worldwide collaboration of scientists conducting research on the fundamental nature of matter. The experiment is located at the Tevatron Collider, at Fermilab. The research is focused on precise studies of interactions of protons and antiprotons at the highest available energies. It involves an intense search for subatomic clues that reveal the character of the building blocks of the universe. This web page provides access to Run II research results of the QCD Physics group, including preliminary, submitted, and published results. Figures and data plots are found in the same directories with their respective papers.
Axial couplings of heavy hadrons from domain-wall lattice QCD
W. Detmold, C.J.D. Lin, S. Meinel
2011-12-01
We calculate matrix elements of the axial current for static-light mesons and baryons in lattice QCD with dynamical domain wall fermions. We use partially quenched heavy hadron chiral perturbation theory in a finite volume to extract the axial couplings g{sub 1}, g{sub 2}, and g{sub 3} from the data. These axial couplings allow the prediction of strong decay rates and enter chiral extrapolations of most lattice results in the b sector. Our calculations are performed with two lattice spacings and with pion masses down to 227 MeV.
Large mass expansion in two-loop QCD corrections of paracharmonium decay
Hasegawa, K.; Pak, Alexey
2008-01-01
We calculate the two-loop QCD corrections to paracharmonium decays {eta}{sub c}{yields}{gamma}{gamma} and {eta}{sub c}{yields}gg involving light-by-light scattering diagrams with light quark loops. Artificial large mass expansion and convergence improvement techniques are used to evaluate these corrections. The obtained corrections to the decays {eta}{sub c}{yields}{gamma}{gamma} and {eta}{sub c}{yields}gg account for -1.25% and -0.73% of the leading order contribution, respectively.
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; Izubuchi, Taku
2015-01-07
The form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in lattice QCD+QED and QED. A non-perturbative treatment of QED is used and is checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed. Statistically significant signals are obtained. Initial results appear promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
Aspects of excited baryon phenomenology in the 1/N{sub c} expansion of QCD
Gonzalez de Urreta, E. J.; Scoccola, Norberto N.
2010-11-12
We report on the application of the 1/N{sub c} expansion of QCD to the description of the properties of non-strange excited baryons belonging to the [70, 1{sup -}]-plet. In particular, we present the results of an improved determination of the corresponding mixing angles obtained by performing a simultaneous fit of masses and strong decay widths. We find {theta}{sub 1} 0.47{+-}0.06 and {theta}{sub 3} = 2.74{+-}0.07. These values are within the range of those determined in previous non-global analyses but have smaller uncertainties.
Constructing QCD one-loop amplitudes (Conference) | SciTech Connect
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... Country of Publication: United States Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AMPLITUDES; ...
Direct measure of quantum correlation
Yu, Chang-shui [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Zhao, Haiqing [School of Science, Dalian Jiaotong University, Dalian 116028 (China)
2011-12-15
The quantumness of the correlation known as quantum correlation is usually measured by quantum discord. So far various quantum discords can be roughly understood as indirect measure by some special discrepancy of two quantities. We present a direct measure of quantum correlation by revealing the difference between the structures of classically and quantum correlated states. Our measure explicitly includes the contributions of the inseparability and local nonorthogonality of the eigenvectors of a density matrix. Besides its relatively easy computability, our measure can provide a unified understanding of quantum correlation of all the present versions.
Spherically symmetric quantum horizons
Bojowald, Martin; Swiderski, Rafal
2005-04-15
Isolated horizon conditions specialized to spherical symmetry can be imposed directly at the quantum level. This answers several questions concerning horizon degrees of freedom, which are seen to be related to orientation, and its fluctuations at the kinematical as well as dynamical level. In particular, in the absence of scalar or fermionic matter the horizon area is an approximate quantum observable. Including different kinds of matter fields allows to probe several aspects of the Hamiltonian constraint of quantum geometry that are important in inhomogeneous situations.
The promise of quantum simulation
Muller, Richard P.; Blume-Kohout, Robin
2015-07-21
In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH+ molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.
The promise of quantum simulation
Muller, Richard P.; Blume-Kohout, Robin
2015-07-21
In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH^{+} molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.
Castagnoli, G. )
1991-08-10
This paper reports that current conceptions of quantum mechanical computers inherit from conventional digital machines two apparently interacting features, machine imperfection and temporal development of the computational process. On account of machine imperfection, the process would become ideally reversible only in the limiting case of zero speed. Therefore the process is irreversible in practice and cannot be considered to be a fundamental quantum one. By giving up classical features and using a linear, reversible and non-sequential representation of the computational process - not realizable in classical machines - the process can be identified with the mathematical form of a quantum steady state. This form of steady quantum computation would seem to have an important bearing on the notion of cognition.
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing...
U.S. Department of Energy (DOE) all webpages (Extended Search)
based on molecular magnets that may make them suitable as qubits for quantum computers. Chemistry Aids Quantum Computing Quantum bits or qubits are the fundamental...
Light-cone quantization and hadron structure
Brodsky, S.J.
1996-04-01
Quantum chromodynamics provides a fundamental description of hadronic and nuclear structure and dynamics in terms of elementary quark and gluon degrees of freedom. In practice, the direct application of QCD to reactions involving the structure of hadrons is extremely complex because of the interplay of nonperturbative effects such as color confinement and multi-quark coherence. In this talk, the author will discuss light-cone quantization and the light-cone Fock expansion as a tractable and consistent representation of relativistic many-body systems and bound states in quantum field theory. The Fock state representation in QCD includes all quantum fluctuations of the hadron wavefunction, including fax off-shell configurations such as intrinsic strangeness and charm and, in the case of nuclei, hidden color. The Fock state components of the hadron with small transverse size, which dominate hard exclusive reactions, have small color dipole moments and thus diminished hadronic interactions. Thus QCD predicts minimal absorptive corrections, i.e., color transparency for quasi-elastic exclusive reactions in nuclear targets at large momentum transfer. In other applications, such as the calculation of the axial, magnetic, and quadrupole moments of light nuclei, the QCD relativistic Fock state description provides new insights which go well beyond the usual assumptions of traditional hadronic and nuclear physics.
Nonperturbative QCD Coupling and its $$\\beta$$-function from Light-Front Holography
Brodskey, Stanley J.; de Teramond, Guy; Deur, Alexandre P.
2010-05-28
The light-front holographic mapping of classical gravity in AdS space, modified by a positive-sign dilaton background, leads to a non-perturbative effective couplingmore » $$\\alpha_s^{AdS}(Q^2)$$. It agrees with hadron physics data extracted from different observables, such as the effective charge defined by the Bjorken sum rule, as well as with the predictions of models with built-in confinement and lattice simulations. It also displays a transition from perturbative to nonperturbative conformal regimes at a momentum scale $$ \\sim 1$$ GeV. The resulting $$\\beta$$-function appears to capture the essential characteristics of the full $$\\beta$$-function of QCD, thus giving further support to the application of the gauge/gravity duality to the confining dynamics of strongly coupled QCD. Commensurate scale relations relate observables to each other without scheme or scale ambiguity. In this paper we extrapolate these relations to the nonperturbative domain, thus extending the range of predictions based on $$\\alpha_s^{AdS}(Q^2)$$.« less
An a0 resonance in strongly coupled πη, KK¯ scattering from lattice QCD
Dudek, Jozef J.; Edwards, Robert G.; Wilson, David J.
2016-05-11
Here, we present the first calculation of coupled-channel meson-meson scattering in the isospinmore » $=1$, $G$-parity negative sector, with channels $$\\pi \\eta$$, $$K\\overline{K}$$ and $$\\pi \\eta'$$, in a first-principles approach to QCD. From the discrete spectrum of eigenstates in three volumes extracted from lattice QCD correlation functions we determine the energy dependence of the $S$-matrix, and find that the $S$-wave features a prominent cusp-like structure in $$\\pi \\eta \\to \\pi \\eta$$ close to $$K\\overline{K}$$ threshold coupled with a rapid turn on of amplitudes leading to the $$K\\overline{K}$$ final-state. This behavior is traced to an $a_0(980)$-like resonance, strongly coupled to both $$\\pi \\eta$$ and $$K\\overline{K}$$, which is identified with a pole in the complex energy plane, appearing on only a single unphysical Riemann sheet. Consideration of $D$-wave scattering suggests a narrow tensor resonance at higher energy.« less
Unraveling the Structure of Hadrons with Effective Field Theories of QCD
Iain Stewart
2004-06-08
Effective Field theory is a powerful framework based on controlled expansions for problems with a natural separation of energy scales. This technique is particularly important for QCD, the theory of strong interactions, due to the vast diversity of phenomena that it describes. Stewart and collaborators have invented a new class of effective theories that can be used in processes with energetic hadrons. These Soft-Collinear Effective Theories provide a unified framework for describing hadronic processes which involve hard probes or the release of a large amount of energy. Many interesting issues about hadronic physics can be addressed with the soft-collinear effective theory. Examples include the size and shape of hadronic form factors, the universality of hadronic distribution functions for a plethora of processes, and the importance of subleading corrections at intermediate energy scales. Effective field theories allow these issues to be addressed using only the underlying symmetries and scales in QCD. Understanding these issues also has a direct impact on other areas of physics, such as on devising clean methods for the measurement of CP violation in the decay of B-mesons. Current progress on the soft-collinear effective theory and related methods is discussed in this report.
Exotic and excited-state radiative transitions in charmonium from lattice QCD
Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.
2009-05-01
We compute, for the first time using lattice QCD methods, radiative transition rates involving excited charmonium states, states of high spin and exotics. Utilizing a large basis of interpolating fields we are able to project out various excited state contributions to three-point correlators computed on quenched anisotropic lattices. In the first lattice QCD calculation of the exoticmore » $$1^{-+}$$ $$\\eta_{c1}$$ radiative decay, we find a large partial width $$\\Gamma(\\eta_{c1} \\to J/\\psi \\gamma) \\sim 100 \\,\\mathrm{keV}$$. We find clear signals for electric dipole and magnetic quadrupole transition form factors in $$\\chi_{c2} \\to J/\\psi \\gamma$$, calculated for the first time in this framework, and study transitions involving excited $$\\psi$$ and $$\\chi_{c1,2}$$ states. We calculate hindered magnetic dipole transition widths without the sensitivity to assumptions made in model studies and find statistically significant signals, including a non-exotic vector hybrid candidate $Y_{\\mathrm{hyb?}} \\to \\et« less
PDF and QCD effects in the precision measurement of the W boson mass at CDF
Beecher, Daniel; /University Coll. London
2011-01-01
A sample of W {yields} e{nu} (W {yields} {mu}{nu}) and Z{sup 0} {yields} e{sup +}e{sup -} (Z{sup 0} {yields} {mu}{sup +}{mu}{sup -}) events recorded by the CDF detector for p{bar p} collisions at {radical}s = 1.96 TeV are used to evaluate the systematic uncertainty in the determination of the W boson mass arising from uncertainties in the parton distribution functions and higher-order QCD effects. The systematic contribution of PDFs is determined to be 10 MeV/c{sup 2} for MSTW2008 NLO and 12 MeV/c{sup 2} for CTEQ6.6. The total systematic contribution arising from higher-order QCD effects in 9 MeV/c{sup 2}. The Z{sup 0} events are used to extract improved estimates of the phenomenological parameters in the BLNY model that describes low transverse momentum.
Baryon spin-flavor structure from an analysis of lattice QCD results of the baryon spectrum
Fernando, I. P.; Goity, J. L.
2015-02-01
The excited baryon masses are analyzed in the framework of the 1/Nc expansion using the available physical masses and also the masses obtained in lattice QCD for different quark masses. The baryon states are organized into irreducible representations of SU(6) x O(3), where the [56,l^{P}=0⁺] ground state and excited baryons, and the [56,2^{+}] and [70}},1^{-}] excited states are analyzed. The analyses are carried out to order O(1/N_{c}) and first order in the quark masses. The issue of state identifications is discussed. Numerous parameter independent mass relations result at those orders, among them the well known Gell-Mann-Okubo and Equal Spacing relations, as well as additional relations involving baryons with different spins. It is observed that such relations are satisfied at the expected level of precision. The main conclusion of the analysis is that qualitatively the dominant physical effects are similar for the physical and the lattice QCD baryons.
Baryon spin-flavor structure from an analysis of lattice QCD results of the baryon spectrum
Fernando, I. P.; Goity, J. L.
2015-02-01
The excited baryon masses are analyzed in the framework of the 1/Nc expansion using the available physical masses and also the masses obtained in lattice QCD for different quark masses. The baryon states are organized into irreducible representations of SU(6) x O(3), where the [56,lP=0⁺] ground state and excited baryons, and the [56,2+] and [70}},1-] excited states are analyzed. The analyses are carried out to order O(1/Nc) and first order in the quark masses. The issue of state identifications is discussed. Numerous parameter independent mass relations result at those orders, among them the well known Gell-Mann-Okubo and Equal Spacing relations,more » as well as additional relations involving baryons with different spins. It is observed that such relations are satisfied at the expected level of precision. The main conclusion of the analysis is that qualitatively the dominant physical effects are similar for the physical and the lattice QCD baryons.« less
Electron-ion collider: The next QCD frontier: Understanding the glue that binds us all
Accardi, A.; Albacete, J. L.; Anselmino, M.; Armesto, N.; Aschenauer, E. C.; Bacchetta, A.; Boer, D.; Brooks, W. K.; Burton, T.; Chang, N. -B.; et al
2016-09-08
This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decadesmore » and, in particular, the focused ten-week program on “Gluons and quark sea at high energies” at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users’ communities of BNL and JLab. Furthermore, this White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier.« less
Effective Hamiltonian for non-leptonic |Delta F| = 1 decays at NNLO in QCD
Gorbahn, Martin; Haisch, Ulrich; /Fermilab
2004-11-01
The authors compute the effective hamiltonian for non-leptonic |{Delta}F| = 1 decays in the standard model including next-to-next-to-leading order QCD corrections. In particular, they present the complete three-loop anomalous dimension matrix describing the mixing of current-current and QCD penguin operators. The calculation is performed in an operator basis which allows to consistently use fully anticommuting {gamma}{sub 5} in dimensional regularization at an arbitrary number of loops. The renormalization scheme dependences and their cancellation in physical quantities is discussed in detail. Furthermore, they demonstrate how the results are transformed to a different basis of effective operators which is frequently adopted in phenomenological applications. They give all necessary two-loop constant terms which allow to obtain the three-loop anomalous dimensions and the corresponding initial conditions of the two-loop Wilson coefficients in the latter scheme. Finally, they solve the renormalization group equation and given the analytic expressions for the low-energy Wilson coefficients relevant for non-leptonic B meson decays beyond next-to-leading order in both renormalization schemes.
The effects of QCD equation of state on the relic density of WIMP dark matter
Drees, Manuel; Hajkarim, Fazlollah; Schmitz, Ernany Rossi
2015-06-12
Weakly Interactive Massive Particles (WIMPs) are the most widely studied candidate particles forming the cold dark matter (CDM) whose existence can be inferred from a wealth of astrophysical and cosmological observations. In the framework of the minimal cosmological model detailed measurements on the cosmic microwave background by the PLANCK collaboration fix the scaled CDM relic density to Ω{sub c}h{sup 2}=0.1193±0.0014, with an error of less than 1.5%. In order to fully exploit this observational precision, theoretical calculations should have a comparable or smaller error. In this paper we use recent lattice QCD calculations to improve the description of the thermal plasma. This affects the predicted relic density of “thermal WIMPs”, which once were in chemical equilibrium with Standard Model particles. For WIMP masses between 3 and 15 GeV, where QCD effects are most important, our predictions differ from earlier results by up to 9% (12%) for pure S-wave (P-wave) annihilation. We use these results to compute the thermally averaged WIMP annihilation cross section that reproduces the correct CDM relic density, for WIMP masses between 0.1 GeV and 10 TeV.
The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD
Beane, S. R.; Chang, E.; Detmold, W.; Lin, H. W.; Luu, T. C.; Orginos, K.; Parreno, A.; Savage, M. J.; Torok, A.; Walker-Loud, A.
2012-02-16
The π+π+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of mπ ≈ 390 MeV with an anisotropic nf = 2+1 clover fermion discretization in four lattice volumes, with spatial extent L ≈ 2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of bs ≈ 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of π+π+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enoughmore » to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: mπ2 a r = 3+O(mπ2/Λχ2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.« less
Turbocharging Quantum Tomography.
Blume-Kohout, Robin J; Gamble, John King,; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael
2015-01-01
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.
Note on quantum Minkowski space
Bentalha, Z.; Tahiri, M.
2008-09-15
In this work, some interesting details about quantum Minkowski space and quantum Lorentz group structures are revealed. The task is accomplished by generalizing an approach adopted in a previous work where quantum rotation group and quantum Euclidean space structures have been investigated. The generalized method is based on a mapping relating the q-spinors (precisely the tensor product of dotted and undotted fondamental q-spinors) to Minkowski q-vectors. As a result of this mapping, the quantum analog of Minkowski space is constructed (with a definite metric). Also, the matrix representation of the quantum Lorentz group is determined together with its corresponding q-deformed orthogonality relation.
Comparison of the attempts of quantum discord and quantum entanglement...
Office of Scientific and Technical Information (OSTI)
Department of Physics and Centre for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 1A7 (Canada) Publication Date: 2011-03-15 OSTI Identifier: ...
CDSS: Dr. Hensinger on Quantum Computing
Office of Energy Efficiency and Renewable Energy (EERE)
Dr. Winfried Hensinger – Professor of Quantum Technologies, Ion Quantum Technology Group, Department of Physics and Astronomy, University of Sussex
Suppression of quantum chaos in a quantum computer hardware
Lages, J.; Shepelyansky, D. L. [Laboratoire de Physique Theorique, UMR 5152 du CNRS, Universite Paul Sabatier, 31062 Toulouse Cedex 4 (France)
2006-08-15
We present numerical and analytical studies of a quantum computer proposed by the Yamamoto group in Phys. Rev. Lett. 89, 017901 (2002). The stable and quantum chaos regimes in the quantum computer hardware are identified as a function of magnetic field gradient and dipole-dipole couplings between qubits on a square lattice. It is shown that a strong magnetic field gradient leads to suppression of quantum chaos.
Maunz, Peter Lukas Wilhelm; Sterk, Jonathan David; Lobser, Daniel; Parekh, Ojas D.; Ryan-Anderson, Ciaran
2016-01-01
In recent years, advanced network analytics have become increasingly important to na- tional security with applications ranging from cyber security to detection and disruption of ter- rorist networks. While classical computing solutions have received considerable investment, the development of quantum algorithms to address problems, such as data mining of attributed relational graphs, is a largely unexplored space. Recent theoretical work has shown that quan- tum algorithms for graph analysis can be more efficient than their classical counterparts. Here, we have implemented a trapped-ion-based two-qubit quantum information proces- sor to address these goals. Building on Sandia's microfabricated silicon surface ion traps, we have designed, realized and characterized a quantum information processor using the hyperfine qubits encoded in two 171 Yb + ions. We have implemented single qubit gates using resonant microwave radiation and have employed Gate set tomography (GST) to characterize the quan- tum process. For the first time, we were able to prove that the quantum process surpasses the fault tolerance thresholds of some quantum codes by demonstrating a diamond norm distance of less than 1 . 9 x 10 [?] 4 . We used Raman transitions in order to manipulate the trapped ions' motion and realize two-qubit gates. We characterized the implemented motion sensitive and insensitive single qubit processes and achieved a maximal process infidelity of 6 . 5 x 10 [?] 5 . We implemented the two-qubit gate proposed by Molmer and Sorensen and achieved a fidelity of more than 97 . 7%.
U.S. Department of Energy (DOE) all webpages (Extended Search)
from this data and used in the analysis of experimental data produced in the collisions of relativistic heavy ions at Brookhaven National Lab and the Large Hadron Collider. ...
Adare, A.
2015-02-02
We present midrapidity charged-pion invariant cross sections, the ratio of the ??to ?? cross sections and the charge-separated double-spin asymmetries in polarized p+p collisions at ?s = 200 GeV. While the cross section measurements are consistent within the errors of next-to-leadingorder (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations over estimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor dependent pion fragmentation functions. The charge-separated pion asymmetries presented here sample anmorex range of ~0.030.16 and provide unique information on the sign of the gluon-helicity distribution.less
Crede, Volker
2013-03-25
The spectrum of excited baryons serves as an excellent probe of quantum chromodynamics (QCD). In particular, highly-excited baryon resonances are sensitive to the details of quark confinement which is only poorly understood within QCD. Facilities worldwide such as Jefferson Lab, ELSA, and MAMI, which study the systematics of hadron spectra in photo- and electroproduction experiments, have accumulated a large amount of data in recent years including unpolarized cross section and polarization data for a large variety of meson-production reactions. These are important steps toward complete experiments that will allow us to unambiguously determine the scattering amplitude in the underlying reactions and to identify the broad and overlapping baryon resonance contributions. Several new nucleon resonances have been proposed and changes to the baryon listing in the 2012 Review of Particle Physics reflect the progress in the field.
The Evolution of Soft Collinear Effective Theory
Lee, Christopher
2015-02-25
Soft Collinear Effective Theory (SCET) is an effective field theory of Quantum Chromodynamics (QCD) for processes where there are energetic, nearly lightlike degrees of freedom interacting with one another via soft radiation. SCET has found many applications in high-energy and nuclear physics, especially in recent years the physics of hadronic jets in e^{+}e^{-}, lepton-hadron, hadron-hadron, and heavy-ion collisions. SCET can be used to factorize multi-scale cross sections in these processes into single-scale hard, collinear, and soft functions, and to evolve these through the renormalization group to resum large logarithms of ratios of the scales that appear in the QCD perturbative expansion, as well as to study properties of nonperturbative effects. We overview the elementary concepts of SCET and describe how they can be applied in high-energy and nuclear physics.
Spin-Flavor van der Waals Forces and NN interaction
Alvaro Calle Cordon, Enrique Ruiz Arriola
2011-12-01
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.
Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Taani, H.; Alexander, J.; Andrews, K. R.; Angerami, A.; Aoki, K.; et al
2015-02-02
We present midrapidity charged-pion invariant cross sections, the ratio of the ?? to ?? cross sections and the charge-separated double-spin asymmetries in polarized p+p collisions at ?s = 200 GeV. While the cross section measurements are consistent within the errors of next-to-leadingorder (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations over estimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor dependent pion fragmentation functions. Thus, the charge-separated pion asymmetries presented heremoresample an x range of ~0.030.16 and provide unique information on the sign of the gluon-helicity distribution.less
Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Ta’ani, H.; Alexander, J.; Andrews, K. R.; Angerami, A.; Aoki, K.; et al
2015-02-02
We present midrapidity charged-pion invariant cross sections, the ratio of the π⁻ to π⁺ cross sections and the charge-separated double-spin asymmetries in polarized p+p collisions at √s = 200 GeV. While the cross section measurements are consistent within the errors of next-to-leadingorder (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations over estimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor dependent pion fragmentation functions. Thus, the charge-separated pion asymmetries presented heremore » sample an x range of ~0.03–0.16 and provide unique information on the sign of the gluon-helicity distribution.« less
Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √s_{NN}=7.7 to 200 GeV
Adamczyk, L.
2015-08-07
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 Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √s_{NN}=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.
The Evolution of Soft Collinear Effective Theory
Lee, Christopher
2015-02-25
Soft Collinear Effective Theory (SCET) is an effective field theory of Quantum Chromodynamics (QCD) for processes where there are energetic, nearly lightlike degrees of freedom interacting with one another via soft radiation. SCET has found many applications in high-energy and nuclear physics, especially in recent years the physics of hadronic jets in e+e-, lepton-hadron, hadron-hadron, and heavy-ion collisions. SCET can be used to factorize multi-scale cross sections in these processes into single-scale hard, collinear, and soft functions, and to evolve these through the renormalization group to resum large logarithms of ratios of the scales that appear in the QCD perturbativemore » expansion, as well as to study properties of nonperturbative effects. We overview the elementary concepts of SCET and describe how they can be applied in high-energy and nuclear physics.« less
Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Ta’ani, H.; Alexander, J.; Andrews, K. R.; Angerami, A.; Aoki, K.; Apadula, N.; Appelt, E.; Aramaki, Y.; Armendariz, R.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belmont, R.; Ben-Benjamin, J.; Bennett, R.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Broxmeyer, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Campbell, S.; Castera, P.; Chen, C. -H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa del Valle, Z.; Connors, M.; Csanád, M.; Csörgő, T.; Dairaku, S.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D’Orazio, L.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; En’yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gal, C.; Garishvili, I.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H. -Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Harper, C.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Issah, M.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; John, D.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. J.; Kim, E. -J.; Kim, Y. -J.; Kim, Y. K.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotov, D.; Král, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miki, K.; Milov, A.; Mitchell, J. T.; Miyachi, Y.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nihashi, M.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O’Brien, E.; Ogilvie, C. A.; Oka, M.; Okada, K.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, S. K.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J. -C.; Pereira, H.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosendahl, S. S. E.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Samsonov, V.; Sano, S.; Sarsour, M.; Sato, T.; Savastio, M.; Sawada, S.; Sedgwick, K.; Seidl, R.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T. -A.; Shigaki, K.; Shim, H. H.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Sodre, T.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Themann, H.; Thomas, D.; Togawa, M.; Tomášek, L.; Tomášek, M.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Utsunomiya, K.; Vale, C.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Yamaguchi, Y. L.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.
2015-02-02
We present midrapidity charged-pion invariant cross sections, the ratio of the π⁻ to π⁺ cross sections and the charge-separated double-spin asymmetries in polarized p+p collisions at √s = 200 GeV. While the cross section measurements are consistent within the errors of next-to-leadingorder (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations over estimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor dependent pion fragmentation functions. Thus, the charge-separated pion asymmetries presented here sample an x range of ~0.03–0.16 and provide unique information on the sign of the gluon-helicity distribution.
INTERACTING QUARK MATTER EQUATION OF STATE FOR COMPACT STARS
Fraga, Eduardo S.; Kurkela, Aleksi; Vuorinen, Aleksi
2014-02-01
Lattice quantum chromodynamics (QCD) studies of the thermodynamics of hot quark-gluon plasma demonstrate the importance of accounting for the interactions of quarks and gluons if one wants to investigate the phase structure of strongly interacting matter. Motivated by this observation and using state-of-the-art results from perturbative QCD, we construct a simple, effective equation of state (EOS) for cold quark matter that consistently incorporates the effects of interactions and furthermore includes a built-in estimate of the inherent systematic uncertainties. This goes beyond the MIT bag model description in a crucial way, yet leads to an EOS that is equally straightforward to use. We also demonstrate that, at moderate densities, our EOS can be made to smoothly connect to hadronic EOSs, with the two exhibiting very similar behavior near the matching region. The resulting hybrid stars are seen to have masses similar to those predicted by the purely nucleonic EOSs.
Quantum Solar | Open Energy Information
Open Energy Information (Open El) [EERE & EIA]
Solar Jump to: navigation, search Name: Quantum Solar Place: Santa Fe, New Mexico Zip: 87507 Product: New Mexico-based PV cell technology company. References: Quantum Solar1 This...
Quasiperiodically kicked quantum systems
Milonni, P.W.; Ackerhalt, J.R.; Goggin, M.E.
1987-02-15
We consider a two-state system kicked quasiperiodically by an external force. When the two kicking frequencies assumed for the force are incommensurate, there can be quantum chaos in the sense that (a) the autocorrelation function of the state vector decays, (b) the power spectrum of the state vector is broadband, and (c) the motion on the Bloch sphere is ergodic. The time evolution of the state vector is nevertheless dynamically stable in the sense that memory of the initial state is retained. We also consider briefly the kicked quantum rotator and find, in agreement with Shepelyansky (Physica 8D, 208 (1983)), that the quantum localization effect is greatly weakened by the presence of two incommensurate driving frequencies.
Sandia National Laboratories: Quantum Systems
U.S. Department of Energy (DOE) all 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 of conventional methods Custom Solutions Quantum Sensing We are leveraging quantum mechanics to enable sensors that go beyond the capabilities of conventional methods. Using the quantized states of matter, it is possible to build exquisite metrology devices such as frequency standards and inertial sensors. Our efforts
Quantum money with classical verification
Gavinsky, Dmitry
2014-12-04
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.
Authentication of quantum messages.
Barnum, Howard; Crépeau, Jean-Claude; Gottesman, D.; Smith, A.; Tapp, Alan
2001-01-01
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.
Jiang, F.-J.; Wiese, U.-J.
2011-04-15
The two-dimensional (2D) spin-(1/2) Heisenberg antiferromagnet with exchange coupling J is investigated on a periodic square lattice of spacing a at very small temperatures using the loop-cluster algorithm. Monte Carlo data for the staggered and uniform susceptibilities are compared with analytic results obtained in the systematic low-energy effective field theory for the staggered magnetization order parameter. The low-energy parameters of the effective theory, i.e., the staggered magnetization density M{sub s}=0.307 43(1)/a{sup 2}, the spin stiffness {rho}{sub s}=0.180 81(11)J, and the spin wave velocity c=1.6586(3)Ja, are determined with very high precision. Our study may serve as a test case for the comparison of lattice quantum chromodynamics Monte Carlo data with analytic predictions of the chiral effective theory for pions and nucleons, which is vital for the quantitative understanding of the strong interaction at low energies.
Short-distance matrix elements for $D$-meson mixing for 2+1 lattice QCD
Chang, Chia Cheng
2015-01-01
We study the short-distance hadronic matrix elements for D-meson mixing with partially quenched N_{f} = 2+1 lattice QCD. We use a large set of the MIMD Lattice Computation Collaboration's gauge configurations with a^{2} tadpole-improved staggered sea quarks and tadpole-improved Lüscher-Weisz gluons. We use the a^{2} tadpole-improved action for valence light quarks and the Sheikoleslami-Wohlert action with the Fermilab interpretation for the valence charm quark. Our calculation covers the complete set of five operators needed to constrain new physics models for D-meson mixing. We match our matrix elements to the MS-NDR scheme evaluated at 3 GeV. We report values for the Beneke-Buchalla-Greub-Lenz-Nierste choice of evanescent operators.
Novel Perspectives from Light-Front QCD, Super-Conformal Algebra, and Light-Front Holography
Brodsky, Stanley J.
2015-12-01
Light-Front Quantization – Dirac’s “Front Form” – provides a physical, frame-independent formalism for hadron dynamics and structure. Observables such as structure functions, transverse momentum distributions, and distribution amplitudes are defined from the hadronic LFWFs. One obtains new insights into the hadronic mass scale, the hadronic spectrum, and the functional form of the QCD running coupling in the nonperturbative domain using light-front holography. In addition, superconformal algebra leads to remarkable supersymmetric relations between mesons and baryons. I also discuss evidence that the antishadowing of nuclear structure functions is nonuniversal; i.e., flavor dependent, and why shadowing and antishadowing phenomena may be incompatible with the momentum and other sum rules for the nuclear parton distribution functions.
Nucleon, $$\\Delta$$ and $$\\Omega$$ excited states in $N_f=2+1$ lattice QCD
John Bulava; Edwards, Robert G.; Engelson, Eric; Joo, Balint; Lin, Huey -Wen; Morningstar, Colin; Richards, David G.; Wallace, Stephen J.
2010-07-22
The energies of the excited states of the Nucleon,more » $$\\Delta$$ and $$\\Omega$$ are computed in lattice QCD, using two light quarks and one strange quark on anisotropic lattices. The calculation is performed at three values of the light quark mass, corresponding to pion masses $$m_{\\pi}$$ = 392(4), 438(3) and 521(3) MeV. We employ the variational method with a large basis of interpolating operators enabling six energies in each irreducible representation of the lattice to be distinguished clearly. We compare our calculation with the low-lying experimental spectrum, with which we find reasonable agreement in the pattern of states. In addition, the need to include operators that couple to the expected multi-hadron states in the spectrum is clearly identified.« less
Quasiparticle description of (2+1)- flavor lattice QCD equation of state
Chandra, Vinod; Ravishankar, V.
2011-10-01
A quasiparticle model has been employed to describe the (2+1)-flavor lattice QCD equation of state with physical quark masses. The interaction part of the equation of state has been mapped to the effective fugacities of otherwise noninteracting quasigluons and quasiquarks. The mapping is found to be exact for the equation of state. The model leads to nontrivial dispersion relations for quasipartons. The dispersion relations, effective quasiparticle number densities, and trace anomaly have been investigated employing the model. A virial expansion for the equation of state has further been obtained to investigate the role of interactions in quark-gluon plasma. Finally, Debye screening in quark-gluon plasma has been studied employing the model.
High-Performance I/O: HDF5 for Lattice QCD
Kurth, Thorsten; Pochinsky, Andrew; Sarje, Abhinav; Syritsyn, Sergey; Walker-Loud, Andre
2015-01-01
Practitioners of lattice QCD/QFT have been some of the primary pioneer users of the state-of-the-art high-performance-computing systems, and contribute towards the stress tests of such new machines as soon as they become available. As with all aspects of high-performance-computing, I/O is becoming an increasingly specialized component of these systems. In order to take advantage of the latest available high-performance I/O infrastructure, to ensure reliability and backwards compatibility of data files, and to help unify the data structures used in lattice codes, we have incorporated parallel HDF5 I/O into the SciDAC supported USQCD software stack. Here we present the design and implementation of this I/O framework. Our HDF5 implementation outperforms optimized QIO at the 10-20% level and leaves room for further improvement by utilizing appropriate dataset chunking.
Real time evolution of non-Gaussian cumulants in the QCD critical regime
Mukherjee, Swagato; Venugopalan, Raju; Yin, Yi
2015-09-23
In this study, we derive a coupled set of equations that describe the nonequilibrium evolution of cumulants of critical fluctuations for spacetime trajectories on the crossover side of the QCD phase diagram. In particular, novel expressions are obtained for the nonequilibrium evolution of non-Gaussian skewness and kurtosis cumulants. UBy utilizing a simple model of the spacetime evolution of a heavy-ion collision, we demonstrate that, depending on the relaxation rate of critical fluctuations, skewness and kurtosis can differ significantly in magnitude as well as in sign from equilibrium expectations. Memory effects are important and shown to persist even for trajectories that skirt the edge of the critical regime. We use phenomenologically motivated parametrizations of freeze-out curves and of the beam-energy dependence of the net baryon chemical potential to explore the implications of our model study for the critical-point search in heavy-ion collisions.
Real time evolution of non-Gaussian cumulants in the QCD critical regime
Mukherjee, Swagato; Venugopalan, Raju; Yin, Yi
2015-09-23
In this study, we derive a coupled set of equations that describe the nonequilibrium evolution of cumulants of critical fluctuations for spacetime trajectories on the crossover side of the QCD phase diagram. In particular, novel expressions are obtained for the nonequilibrium evolution of non-Gaussian skewness and kurtosis cumulants. UBy utilizing a simple model of the spacetime evolution of a heavy-ion collision, we demonstrate that, depending on the relaxation rate of critical fluctuations, skewness and kurtosis can differ significantly in magnitude as well as in sign from equilibrium expectations. Memory effects are important and shown to persist even for trajectories thatmore » skirt the edge of the critical regime. We use phenomenologically motivated parametrizations of freeze-out curves and of the beam-energy dependence of the net baryon chemical potential to explore the implications of our model study for the critical-point search in heavy-ion collisions.« less
$$B\\to\\pi\\ell\\ell$$ Form Factors for New-Physics Searches from Lattice QCD
Bailey, Jon A.
2015-10-07
The rare decay B→πℓ+ℓ- arises from b→d flavor-changing neutral currents and could be sensitive to physics beyond the standard model. Here, we present the first ab initio QCD calculation of the B→π tensor form factor fT. Together with the vector and scalar form factors f+ and f0 from our companion work [J. A. Bailey et al., Phys. Rev. D 92, 014024 (2015)], these parametrize the hadronic contribution to B→π semileptonic decays in any extension of the standard model. We obtain the total branching ratio BR(B+→π+μ+μ-)=20.4(2.1)×10-9 in the standard model, which is the most precise theoretical determination to date, and agreesmore » with the recent measurement from the LHCb experiment [R. Aaij et al., J. High Energy Phys. 12 (2012) 125].« less
Quantum positron acoustic waves
Metref, Hassina; Tribeche, Mouloud
2014-12-15
Nonlinear quantum positron-acoustic (QPA) waves are investigated for the first time, within the theoretical framework of the quantum hydrodynamic model. In the small but finite amplitude limit, both deformed Korteweg-de Vries and generalized Korteweg-de Vries equations governing, respectively, the dynamics of QPA solitary waves and double-layers are derived. Moreover, a full finite amplitude analysis is undertaken, and a numerical integration of the obtained highly nonlinear equations is carried out. The results complement our previously published results on this problem.
Efetov, K.B. [Max-Planck Institut fuer Physik komplexer Systeme, Heisenbergstrasse 1, 70569 Stuttgart (Germany)] [Max-Planck Institut fuer Physik komplexer Systeme, Heisenbergstrasse 1, 70569 Stuttgart (Germany); [L.D. Landau Institute for Theoretical Physics, Moscow (Russia)
1997-07-01
Quantum disordered problems with a direction (imaginary vector potential) are discussed and mapped onto a supermatrix {sigma} model. It is argued that the 0D version of the {sigma} model may describe a broad class of phenomena that can be called directed quantum chaos. It is demonstrated by explicit calculations that these problems are equivalent to those of random asymmetric or non-Hermitian matrices. A joint probability of complex eigenvalues is obtained. The fraction of states with real eigenvalues proves to be always finite for time reversal invariant systems. {copyright} {ital 1997} {ital The American Physical Society}
Quantum Statistical Testing of a Quantum Random Number Generator
Humble, Travis S
2014-01-01
The unobservable elements in a quantum technology, e.g., the quantum state, complicate system verification against promised behavior. Using model-based system engineering, we present methods for verifying the opera- tion of a prototypical quantum random number generator. We begin with the algorithmic design of the QRNG followed by the synthesis of its physical design requirements. We next discuss how quantum statistical testing can be used to verify device behavior as well as detect device bias. We conclude by highlighting how system design and verification methods must influence effort to certify future quantum technologies.
Novel Perspectives for Hadron Physics
Brodsky, Stanley J.; /SLAC
2012-03-09
I discuss several novel and unexpected aspects of quantum chromodynamics. These include: (a) the nonperturbative origin of intrinsic strange, charm and bottom quarks in the nucleon at large x; the breakdown of pQCD factorization theorems due to the lensing effects of initial- and final-state interactions; (b) important corrections to pQCD scaling for inclusive reactions due to processes in which hadrons are created at high transverse momentum directly in the hard processes and their relation to the baryon anomaly in high-centrality heavy-ion collisions; and (c) the nonuniversality of quark distributions in nuclei. I also discuss some novel theoretical perspectives in QCD: (a) light-front holography - a relativistic color-confining first approximation to QCD based on the AdS/CFT correspondence principle; (b) the principle of maximum conformality - a method which determines the renormalization scale at finite order in perturbation theory yielding scheme independent results; (c) the replacement of quark and gluon vacuum condensates by 'in-hadron condensates' and how this helps to resolve the conflict between QCD vacuum and the cosmological constant.
The Future of Hadrons: The Nexus of Subatomic Physics
Quigg, Chris
2011-09-01
The author offers brief observations on matters discussed at the XIV International Conference on Hadron Spectroscopy and explore prospects for hadron physics. Quantum chromodynamics (QCD) has been validated as a new law of nature. It is internally consistent up to very high energies, and so could be a complete theory of the strong interactions. Whether QCD is the final answer for the strong interactions is a subject for continuing experimental tests, which are being extended in experimentation at the Large Hadron Collider. Beyond the comparison of perturbative calculations with experiment, it remains critically important to test the confinement hypothesis by searching for free quarks, or for signatures of unconfined color. Sensitive negative searches for quarks continue to be interesting, and the definitive observation of free quarks would be revolutionary. Breakdowns of factorization would compromise the utility of perturbative QCD. Other discoveries that would require small or large revisions to QCD include the observation of new kinds of colored matter beyond quarks and gluons, the discovery that quarks are composite, or evidence that SU(3){sub c} gauge symmetry is the vestige of a larger, spontaneously broken, color symmetry. While probing our underlying theory for weakness or new openings, we have plenty to do to apply QCD to myriad experimental settings, to learn its implications for matter under unusual conditions, and to become more adept at calculating its consequences. New experimental tools provide the means for progress on a very broad front.
Deur, Alexandre; Brodsky, Stanley J.; de Teramond, Guy F.
2015-04-06
Quantum Chromodynamics (QCD) provides a fundamental description of the physics binding quarks into protons, neutrons, and other hadrons. QCD is well understood at short distances where perturbative calculations are feasible. Establishing an explicit relation between this regime and the large-distance physics of quark confinement has been a long-sought goal. A major challenge is to relate the parameter Λ_{s}, which controls the predictions of perturbative QCD (pQCD) at short distances, to the masses of hadrons. Here we show how new theoretical insights into QCD's behavior at large and small distances lead to an analytical relation between hadronic masses and Λ_{s}. The resulting prediction, Λ_{s} = 0.341 ± 0.024 GeV agrees well with the experimental value 0.339 ± 0.016 GeV. Conversely, the experimental value of Λ_{s} can be used to predict the masses of hadrons, a task which had so far only been accomplished through intensive numerical lattice calculations, requiring several phenomenological input parameters.
Comparison of quantum confinement effects between quantum wires and dots
Li, Jingbo; Wang, Lin-Wang
2004-03-30
Dimensionality is an important factor to govern the electronic structures of semiconductor nanocrystals. The quantum confinement energies in one-dimensional quantum wires and zero-dimensional quantum dots are quite different. Using large-scale first-principles calculations, we systematically study the electronic structures of semiconductor (including group IV, III-V, and II-VI) surface-passivated quantum wires and dots. The band-gap energies of quantum wires and dots have the same scaling with diameter for a given material. The ratio of band-gap-increases between quantum wires and dots is material-dependent, and slightly deviates from 0.586 predicted by effective-mass approximation. Highly linear polarization of photoluminescence in quantum wires is found. The degree of polarization decreases with the increasing temperature and size.
Nanowire terahertz quantum cascade lasers
Grange, Thomas
2014-10-06
Quantum cascade lasers made of nanowire axial heterostructures are proposed. The dissipative quantum dynamics of their carriers is theoretically investigated using non-equilibrium Green functions. Their transport and gain properties are calculated for varying nanowire thickness, from the classical-wire regime to the quantum-wire regime. Our calculation shows that the lateral quantum confinement provided by the nanowires allows an increase of the maximum operation temperature and a strong reduction of the current density threshold compared to conventional terahertz quantum cascade lasers.
National Computational Infrastructure for Lattice Gauge Theory
Brower, Richard C.
2014-04-15
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
Deformation Quantization: Quantum Mechanic Lives and Works in...
Office of Scientific and Technical Information (OSTI)
It has been useful in describing quantum flows in: quantum optics; nuclear physics; decoherence (eg, quantum computing); quantum chaos; 'Welcher Weg' discussions; semiclassical ...
Deformation Quantization: Quantum Mechanic Lives and Works in...
Office of Scientific and Technical Information (OSTI)
of the density matrix. It has been useful in describing quantum flows in: quantum optics; nuclear physics; decoherence (eg, quantum computing); quantum chaos; 'Welcher Weg'...
Quantum probabilities from quantum entanglement: experimentally unpacking the Born rule
Harris, Jérémie; Bouchard, Frédéric; Santamato, Enrico; Zurek, Wojciech H.; Boyd, Robert W.; Karimi, Ebrahim
2016-05-11
The Born rule, a foundational axiom used to deduce probabilities of events from wavefunctions, is indispensable in the everyday practice of quantum physics. It is also key in the quest to reconcile the ostensibly inconsistent laws of the quantum and classical realms, as it confers physical significance to reduced density matrices, the essential tools of decoherence theory. Following Bohr's Copenhagen interpretation, textbooks postulate the Born rule outright. But, recent attempts to derive it from other quantum principles have been successful, holding promise for simplifying and clarifying the quantum foundational bedrock. Moreover, a major family of derivations is based on envariance,more » a recently discovered symmetry of entangled quantum states. Here, we identify and experimentally test three premises central to these envariance-based derivations, thus demonstrating, in the microworld, the symmetries from which the Born rule is derived. Furthermore, we demonstrate envariance in a purely local quantum system, showing its independence from relativistic causality.« less
Precise B, B{sub s}, and B{sub c} meson spectroscopy from full lattice QCD
Gregory, Eric B.; Davies, Christine T. H.; Kendall, Iain D.; Koponen, Jonna; Wong, Kit; Follana, Eduardo; Gamiz, Elvira; Lepage, G. Peter; Mueller, Eike H.; Na, Heechang; Shigemitsu, Junko
2011-01-01
We give the first accurate results for B and B{sub s} meson masses from lattice QCD including the effect of u, d, and s sea quarks, and we improve an earlier value for the B{sub c} meson mass. By using the highly improved staggered quark (HISQ) action for u/d, s, and c quarks and NRQCD for the b quarks, we are able to achieve an accuracy in the masses of around 10 MeV. Our results are: m{sub B}=5.291(18) GeV, m{sub B{sub s}}=5.363(11) GeV, and m{sub B{sub c}}=6.280(10) GeV. Note that all QCD parameters here are tuned from other calculations, so these are parameter free-tests of QCD against experiment. We also give scalar, B{sub s0}* and axial-vector, B{sub s1} meson masses. We find these to be slightly below threshold for decay to BK and B*K, respectively.
Calculation of the heavy-hadron axial couplings g1, g2, and g3 using lattice QCD
Will Detmold, David Lin, Stefan Meinel
2012-06-01
In a recent paper [arXiv:1109.2480] we have reported on a lattice QCD calculation of the heavy-hadron axial couplings g{sub 1}, g{sub 2}, and g{sub 3}. These quantities are low-energy constants of heavy-hadron chiral perturbation theory (HH{chi}PT) and are related to the B*B{pi}, {Sigma}{sub b}*{Sigma}{sub b}{pi}, and {Sigma}{sub b}{sup (*)}{Lambda}{sub b}{pi} couplings. In the following, we discuss important details of the calculation and give further results. To determine the axial couplings, we explicitly match the matrix elements of the axial current in QCD with the corresponding matrix elements in HH{chi}PT. We construct the ratios of correlation functions used to calculate the matrix elements in lattice QCD, and study the contributions from excited states. We present the complete numerical results and discuss the data analysis in depth. In particular, we demonstrate the convergence of SU(4|2) HH{chi}PT for the axial current matrix elements at pion masses up to about 400 MeV and show the impact of the nonanalytic loop contributions. Finally, we present additional predictions for strong and radiative decay widths of charm and bottom baryons.
Hioe, W. ); Goto, E. )
1991-01-01
The quantum flux parametron (QFP) is an offspring of the parametron, an early flux-based logic device, and the Josephson junction. It is a single flux quantum device that works completely in the superconductive mode. While it has the speed of other Josephson devices that work on switching between the voltage and superconductive modes, its power is about one thousand times less. Hence, it promises to be an attractive alternative to both transistors and other Josephson devices. This book reports the latest research results on QFP applications as a logic device. In particular, a number of auxiliary circuits and a new logic gate are proposed for improving the device margin. Samples of these circuits and logic gate have been fabricated.
Hosur, Pavan; Qi, Xiao-Liang; Roberts, Daniel A.; Yoshida, Beni
2016-02-01
For this research, we study chaos and scrambling in unitary channels by considering their entanglement properties as states. Using out-of-time-order correlation functions to diagnose chaos, we characterize the ability of a channel to process quantum information. We show that the generic decay of such correlators implies that any input subsystem must have near vanishing mutual information with almost all partitions of the output. Additionally, we propose the negativity of the tripartite information of the channel as a general diagnostic of scrambling. This measures the delocalization of information and is closely related to the decay of out-of-time-order correlators. We back upmore » our results with numerics in two non-integrable models and analytic results in a perfect tensor network model of chaotic time evolution. In conclusion, these results show that the butterfly effect in quantum systems implies the information-theoretic definition of scrambling.« less
Quantum-to-classical crossover near quantum critical point
Vasin, M.; Ryzhov, V.; Vinokur, V. M.
2015-12-21
A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transitionmore » from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d+zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T)ε[0, 1] decreases with the temperature such that Λ(T=0) = 1 and Λ(T →∞) = 0. Lastly, our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.« less
Quantum-to-classical crossover near quantum critical point
Vasin, M.; Ryzhov, V.; Vinokur, V. M.
2015-12-21
A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d+zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T)ε[0, 1] decreases with the temperature such that Λ(T=0) = 1 and Λ(T →∞) = 0. Lastly, our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.
Quantum Computing: Solving Complex Problems
DiVincenzo, David [IBM Watson Research Center
2016-07-12
One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.
Quantum error-correcting codes and devices
Gottesman, Daniel
2000-10-03
A method of forming quantum error-correcting codes by first forming a stabilizer for a Hilbert space. A quantum information processing device can be formed to implement such quantum codes.
Resonances in coupled pi K, eta K scattering from lattice QCD
Wilson, David J.; Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.
2015-03-10
Coupled-channel ?K and ?K scattering amplitudes are determined by studying the finite-volume energy spectra obtained from dynamical lattice QCD calculations. Using a large basis of interpolating operators, including both those resembling a qq-bar construction and those resembling a pair of mesons with relative momentum, a reliable excited-state spectrum can be obtained. Working at m? = 391 MeV, we find a gradual increase in the JP = 0+ ?K phase-shift which may be identified with a broad scalar resonance that couples strongly to ?K and weakly to ?K. The low-energy behavior of this amplitude suggests a virtual bound-state that may bemorerelated to the ? resonance. A bound state with JP = 1- is found very close to the ?K threshold energy, whose coupling to the ?K channel is compatible with that of the experimental K*(892). Evidence is found for a narrow resonance in JP = 2+. Isospin3/2 ?K scattering is also studied and non-resonant phase-shifts spanning the whole elastic scattering region are obtained.less
$B\\to\\pi\\ell\\ell$ Form Factors for New-Physics Searches from Lattice QCD
Bailey, Jon A.
2015-10-07
The rare decay B→πℓ^{+}ℓ^{-} arises from b→d flavor-changing neutral currents and could be sensitive to physics beyond the standard model. Here, we present the first ab initio QCD calculation of the B→π tensor form factor f_{T}. Together with the vector and scalar form factors f_{+} and f_{0} from our companion work [J. A. Bailey et al., Phys. Rev. D 92, 014024 (2015)], these parametrize the hadronic contribution to B→π semileptonic decays in any extension of the standard model. We obtain the total branching ratio BR(B^{+}→π^{+}μ^{+}μ^{-})=20.4(2.1)×10^{-9} in the standard model, which is the most precise theoretical determination to date, and agrees with the recent measurement from the LHCb experiment [R. Aaij et al., J. High Energy Phys. 12 (2012) 125].
B{yields}S transition form factors in the perturbative QCD approach
Li Runhui; Lue Caidian; Wang Wei; Wang Xiaoxia
2009-01-01
Under two different scenarios for the light scalar mesons, we investigate the transition form factors of B(B{sub s}) mesons decay into a scalar meson in the perturbative QCD approach. In the large recoiling region, the form factors are dominated by the short-distance dynamics and can be calculated using perturbation theory. We adopt the dipole parametrization to recast the q{sup 2} dependence of the form factors. Since the decay constants defined by the scalar current are large, our predictions on the B{yields}S form factors are much larger than the B{yields}P transitions, especially in the second scenario. Contributions from various light-cone distribution amplitudes (LCDAs) are elaborated and we find that the twist-3 LCDAs provide more than one-half of the contributions to the form factors. The two terms of the twist-2 LCDAs give destructive contributions in the first scenario while they give constructive contributions in the second scenario. With the form factors, we also predict the decay width and branching ratios of the semileptonic B{yields}Sl{nu} and B{yields}Sl{sup +}l{sup -} decays. The branching ratios of B{yields}Sl{nu} channels are found to have the order of 10{sup -4} while those of B{yields}Sl{sup +}l{sup -} have the order of 10{sup -7}. These predictions can be tested by the future experiments.
The Neutral kaon mixing parameter B(K) from unquenched mixed-action lattice QCD
Christopher Aubin, Jack Laiho, Ruth S. Van de Water
2010-01-01
We calculate the neutral kaon mixing parameter B{sub K} in unquenched lattice QCD using asqtad-improved staggered sea quarks and domain-wall valence quarks. We use the '2+1' flavor gauge configurations generated by the MILC Collaboration, and simulate with multiple valence and sea quark masses at two lattice spacings of a {approx} 0.12 fm and a {approx} 0.09 fm. We match the lattice determination of B{sub K} to the continuum value using the nonperturbative method of Rome-Southampton, and extrapolate B{sub K} to the continuum and physical quark masses using mixed action chiral perturbation theory. The 'mixed-action' method enables us to control all sources of systematic uncertainty and therefore to precisely determine B{sub K}; we find a value of B{sub K}{sup {ovr MS},NDR} (2 GeV) = 0.527(6)(21), where the first error is statistical and the second is systematic.
A study on the interplay between perturbative QCD and CSS/TMD formalism in SIDIS processes
Boglione, M.; Gonzalez Hernandez, J. O.; Melis, S.; Prokudin, A.
2015-02-16
We study the Semi-Inclusive Deep Inelastic Scattering (SIDIS) cross section as a function of the transverse momentum, _{qT}. In order to describe it over a wide region of _{qT}, soft gluon resummation has to be performed. Here we will use the original Collins-Soper-Sterman (CSS) formalism; however, the same procedure would hold within the improved Transverse Momentum Dependent (TMD) framework. We study the matching between the region where fixed order perturbative QCD can successfully be applied and the region where soft gluon resummation is necessary. We find that the commonly used prescription of matching through the so-called Y-factor cannot be applied in the SIDIS kinematical configurations we examine. In particular, the non-perturbative component of the resummed cross section turns out to play a crucial role and should not be overlooked even at relatively high energies. As a result, the perturbative expansion of the resummed cross section in the matching region is not as reliable as it is usually believed and its treatment requires special attention.
Λb→pl⁻ν¯l form factors from lattice QCD with static b quarks
Detmold, William; Lin, C.-J. David; Meinel, Stefan; Wingate, Matthew
2013-07-23
We present a lattice QCD calculation of form factors for the decay Λb→pμ⁻ν¯μ, which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element |Vub| at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Λb→pμ⁻ν¯μ differential decay rate in the range 14more » GeV²≤q²≤q²max, and obtain the integral ∫q²max 14 GeV²[dΓ/dq²]dq²/|Vub|²=15.3±4.2 ps⁻¹. Combined with future experimental data, this will give a novel determination of |Vub| with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.« less
Resonances in coupled πK, ηK scattering from lattice QCD
Wilson, David J.; Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.
2015-03-10
Coupled-channel πK and ηK scattering amplitudes are determined by studying the finite-volume energy spectra obtained from dynamical lattice QCD calculations. Using a large basis of interpolating operators, including both those resembling a qq-bar construction and those resembling a pair of mesons with relative momentum, a reliable excited-state spectrum can be obtained. Working at mπ = 391 MeV, we find a gradual increase in the JP = 0+ πK phase-shift which may be identified with a broad scalar resonance that couples strongly to πK and weakly to ηK. The low-energy behavior of this amplitude suggests a virtual bound-state that may bemore » related to the κ resonance. A bound state with JP = 1- is found very close to the πK threshold energy, whose coupling to the πK channel is compatible with that of the experimental K*(892). Evidence is found for a narrow resonance in JP = 2+. Isospin–3/2 πK scattering is also studied and non-resonant phase-shifts spanning the whole elastic scattering region are obtained.« less
Resonances in coupled πK, ηK scattering from lattice QCD
Wilson, David J.; Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.
2015-03-10
Coupled-channel πK and ηK scattering amplitudes are determined by studying the finite-volume energy spectra obtained from dynamical lattice QCD calculations. Using a large basis of interpolating operators, including both those resembling a qq-bar construction and those resembling a pair of mesons with relative momentum, a reliable excited-state spectrum can be obtained. Working at mπ = 391 MeV, we find a gradual increase in the JP = 0+ πK phase-shift which may be identified with a broad scalar resonance that couples strongly to πK and weakly to ηK. The low-energy behavior of this amplitude suggests a virtual bound-state that may be related to the κ resonance. A bound state with JP = 1- is found very close to the πK threshold energy, whose coupling to the πK channel is compatible with that of the experimental K*(892). Evidence is found for a narrow resonance in JP = 2+. Isospin–3/2 πK scattering is also studied and non-resonant phase-shifts spanning the whole elastic scattering region are obtained.
Hadronic final states in high -pT QCD at CDF
Matera, Keith
2013-11-18
The heavy quark content of gauge boson events is of great interest to studies of QCD. These events probe the gluon and heavy-quark parton distribution functions of the proton, and also provide a measurement of the rate of final state gluon splitting to heavy flavor. In addition, gauge boson plus heavy quark events are representative of backgrounds to Higgs, single top, and supersymmetric particle searches. Recent work with the CDF II detector at the Fermilab Tevatron has measured the cross-section of several gauge boson plus heavy flavor production processes, including the first Tevatron observation of specific charm process p{p bar} ? W +c. Results are found to be in agreement with NLO predictions that include an enhanced rate of g ? {cc bar}/bb splitting. Lastly, a new analysis promises to probe a lower pT (c) region than has been previously explored, by fully reconstructing D* ? D0(K?)? decays in the full CDF dataset (9.7 fb?1).
Khodadi, M. Sepangi, H.R.
2014-07-15
We study the phase transition from quarkgluon plasma to hadrons in the early universe in the context of non-equilibrium thermodynamics. According to the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electro-weak transition has occurred when the universe was about 110?s old. We focus attention on such a phase transition in the presence of a viscous relativistic cosmological background fluid in the framework of non-detailed balance Ho?avaLifshitz cosmology within an effective model of QCD. We consider a flat FriedmannRobertsonWalker universe filled with a non-causal and a causal bulk viscous cosmological fluid respectively and investigate the effects of the running coupling constants of Ho?avaLifshitz gravity, ?, on the evolution of the physical quantities relevant to a description of the early universe, namely, the temperature T, scale factor a, deceleration parameter q and dimensionless ratio of the bulk viscosity coefficient to entropy density (?)/s . We assume that the bulk viscosity cosmological background fluid obeys the evolution equation of the steady truncated (Eckart) and full version of the IsraelStewart fluid, respectively. -- Highlights: In this paper we have studied quarkhadron phase transition in the early universe in the context of the Ho?avaLifshitz model. We use a flat FRW universe with the bulk viscosity cosmological background fluid obeying the evolution equation of the steady truncated (Eckart) and full version of the IsraelStewart fluid, respectively.
Quantum Information: Opportunities and Challenges
Bennink, Ryan S
2008-01-01
Modern society is shaped by the ability to transmit, manipulate, and store large amounts of information. Although we tend to think of information as abstract, information is physical, and computing is a physical process. How then should we understand information in a quantum world, in which physical systems may exist in multiple states at once and are altered by the very act of observation? This question has evolved into an exciting new field of research called Quantum Information (QI). QI challenges many accepted rules and practices in computer science. For example, a quantum computer would turn certain hard problems into soft problems, and would render common computationally-secure encryption methods (such as RSA) insecure. At the same time, quantum communication would provide an unprecedented kind of intrinsic information security at the level of the smallest physical objects used to store or transmit the information. This talk provides a general introduction to the subject of quantum information and its relevance to cyber security. In the first part, two of the stranger aspects of quantum physics namely, superposition and uncertainty are explained, along with their relation to the concept of information. These ideas are illustrated with a few examples: quantum ID cards, quantum key distribution, and Grover s quantum search algorithm. The state-of-the-art in quantum computing and communication hardware is then discussed, along with the daunting technological challenges that must be overcome. Relevant experimental and theoretical efforts at ORNL are highlighted. The talk concludes with speculations on the short- and long-term impact of quantum information on cyber security.
Quantum Enabled Security (QES) for Optical Communications
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Laboratory has developed Quantum Enabled Security (QES), a revolutionary new cybersecurity capability using quantum (single-photon) communications integrated with optical...
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing...
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Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Wednesday, 26 August 2009 00:00 Rotaxanes are...
Applied Quantum Technology AQT | Open Energy Information
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Second Generation Fractional Quantum Hall Effect
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Generation Fractional Quantum Hall Effect - Sandia Energy Energy Search Icon Sandia Home ... Second Generation Fractional Quantum Hall Effect HomeHighlights - Energy Research...
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Quantum emitters dynamically coupled to a quantum field
Acevedo, O. L.; Quiroga, L.; Rodrguez, F. J.; Johnson, N. F.
2013-12-04
We study theoretically the dynamical response of a set of solid-state quantum emitters arbitrarily coupled to a single-mode microcavity system. Ramping the matter-field coupling strength in round trips, we quantify the hysteresis or irreversible quantum dynamics. The matter-field system is modeled as a finite-size Dicke model which has previously been used to describe equilibrium (including quantum phase transition) properties of systems such as quantum dots in a microcavity. Here we extend this model to address non-equilibrium situations. Analyzing the systems quantum fidelity, we find that the near-adiabatic regime exhibits the richest phenomena, with a strong asymmetry in the internal collective dynamics depending on which phase is chosen as the starting point. We also explore signatures of the crossing of the critical points on the radiation subsystem by monitoring its Wigner function; then, the subsystem can exhibit the emergence of non-classicality and complexity.
Quantum simulation of quantum field theory using continuous variables
Marshall, Kevin; Pooser, Raphael C.; Siopsis, George; Weedbrook, Christian
2015-12-14
Much progress has been made in the field of quantum computing using continuous variables over the last couple of years. This includes the generation of extremely large entangled cluster states (10,000 modes, in fact) as well as a fault tolerant architecture. This has lead to the point that continuous-variable quantum computing can indeed be thought of as a viable alternative for universal quantum computing. With that in mind, we present a new algorithm for continuous-variable quantum computers which gives an exponential speedup over the best known classical methods. Specifically, this relates to efficiently calculating the scattering amplitudes in scalar bosonicmore » quantum field theory, a problem that is known to be hard using a classical computer. Thus, we give an experimental implementation based on cluster states that is feasible with today's technology.« less
Quantum simulation of quantum field theory using continuous variables
Marshall, Kevin; Pooser, Raphael C.; Siopsis, George; Weedbrook, Christian
2015-12-14
Much progress has been made in the field of quantum computing using continuous variables over the last couple of years. This includes the generation of extremely large entangled cluster states (10,000 modes, in fact) as well as a fault tolerant architecture. This has lead to the point that continuous-variable quantum computing can indeed be thought of as a viable alternative for universal quantum computing. With that in mind, we present a new algorithm for continuous-variable quantum computers which gives an exponential speedup over the best known classical methods. Specifically, this relates to efficiently calculating the scattering amplitudes in scalar bosonic quantum field theory, a problem that is known to be hard using a classical computer. Thus, we give an experimental implementation based on cluster states that is feasible with today's technology.
Quantum Darwinism, Decoherence, and the Randomness of Quantum Jumps
Zurek, Wojciech H.
2014-06-05
Tracing flows of information in our quantum Universe explains why we see the world as classical. Quantum principle of superposition decrees every combination of quantum states a legal quantum state. This is at odds with our experience. Decoherence selects preferred pointer states that survive interaction with the environment. They are localized and effectively classical. They persist while their superpositions decohere. Here we consider emergence of `the classical' starting at a more fundamental pre-decoherence level, tracing the origin of preferred pointer states and deducing their probabilities from the core quantum postulates. We also explore role of the environment as medium through which observers acquire information. This mode of information transfer leads to perception of objective classical reality.
Quantum interference within the complex quantum Hamilton-Jacobi formalism
Chou, Chia-Chun; Sanz, Angel S.; Miret-Artes, Salvador; Wyatt, Robert E.
2010-10-15
Quantum interference is investigated within the complex quantum Hamilton-Jacobi formalism. As shown in a previous work [Phys. Rev. Lett. 102 (2009) 250401], complex quantum trajectories display helical wrapping around stagnation tubes and hyperbolic deflection near vortical tubes, these structures being prominent features of quantum caves in space-time Argand plots. Here, we further analyze the divergence and vorticity of the quantum momentum function along streamlines near poles, showing the intricacy of the complex dynamics. Nevertheless, despite this behavior, we show that the appearance of the well-known interference features (on the real axis) can be easily understood in terms of the rotation of the nodal line in the complex plane. This offers a unified description of interference as well as an elegant and practical method to compute the lifetime for interference features, defined in terms of the average wrapping time, i.e., considering such features as a resonant process.
Ma, Hong -Hao; Wu, Xing -Gang; Ma, Yang; Brodsky, Stanley J.; Mojaza, Matin
2015-05-26
A key problem in making precise perturbative QCD (pQCD) predictions is how to set the renormalization scale of the running coupling unambiguously at each finite order. The elimination of the uncertainty in setting the renormalization scale in pQCD will greatly increase the precision of collider tests of the Standard Model and the sensitivity to new phenomena. Renormalization group invariance requires that predictions for observables must also be independent on the choice of the renormalization scheme. The well-known Brodsky-Lepage-Mackenzie (BLM) approach cannot be easily extended beyond next-to-next-to-leading order of pQCD. Several suggestions have been proposed to extend the BLM approach to all orders. In this paper we discuss two distinct methods. One is based on the Principle of Maximum Conformality (PMC), which provides a systematic all-orders method to eliminate the scale and scheme ambiguities of pQCD. The PMC extends the BLM procedure to all orders using renormalization group methods; as an outcome, it significantly improves the pQCD convergence by eliminating renormalon divergences. An alternative method is the sequential extended BLM (seBLM) approach, which has been primarily designed to improve the convergence of pQCD series. The seBLM, as originally proposed, introduces auxiliary fields and follows the pattern of the ?0-expansion to fix the renormalization scale. However, the seBLM requires a recomputation of pQCD amplitudes including the auxiliary fields; due to the limited availability of calculations using these auxiliary fields, the seBLM has only been applied to a few processes at low orders. In order to avoid the complications of adding extra fields, we propose a modified version of seBLM which allows us to apply this method to higher orders. As a result, we then perform detailed numerical comparisons of the two alternative scale-setting approaches by investigating their predictions for the annihilation cross section ratio R
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Quantum gravity slows inflation
Tsamis, N.C. |; Woodard, R.P.
1996-02-01
We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is T{sup 3} {times} {Re}. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-pertubatively large at late times. By exploiting Feynman`s tree theorem we show that all higher loops act in the same sense. 18 refs., 1 fig.
QUANTUM MECHANICS WITHOUT STATISTICAL POSTULATES
G. GEIGER; ET AL
2000-11-01
The Bohmian formulation of quantum mechanics describes the measurement process in an intuitive way without a reduction postulate. Due to the chaotic motion of the hidden classical particle all statistical features of quantum mechanics during a sequence of repeated measurements can be derived in the framework of a deterministic single system theory.
PERTURBATION APPROACH FOR QUANTUM COMPUTATION
G. P. BERMAN; D. I. KAMENEV; V. I. TSIFRINOVICH
2001-04-01
We discuss how to simulate errors in the implementation of simple quantum logic operations in a nuclear spin quantum computer with many qubits, using radio-frequency pulses. We verify our perturbation approach using the exact solutions for relatively small (L = 10) number of qubits.
Quantum Criticality and Black Holes
Sachdev, Subir [Harvard University, Cambridge, Massachusetts, United States
2016-07-12
I will describe the behavior of a variety of condensed matter systems in the vicinity of zero temperature quantum phase transitions. There is a remarkable analogy between the hydrodynamics of such systems and the quantum theory of black holes. I will show how insights from this analogy have shed light on recent experiments on the cuprate high temperature superconductors. Studies of new materials and trapped ultracold atoms are yielding new quantum phases, with novel forms of quantum entanglement. Some materials are of technological importance: e.g. high temperature superconductors. Exact solutions via black hole mapping have yielded first exact results for transport coefficients in interacting many-body systems, and were valuable in determining general structure of hydrodynamics. Theory of VBS order and Nernst effect in cuprates. Tabletop 'laboratories for the entire universe': quantum mechanics of black holes, quark-gluon plasma, neutrons stars, and big-bang physics.
Quantum technology and its applications
Boshier, Malcolm; Berkeland, Dana; Govindan, Tr; Abo - Shaeer, Jamil
2010-12-10
Quantum states of matter can be exploited as high performance sensors for measuring time, gravity, rotation, and electromagnetic fields, and quantum states of light provide powerful new tools for imaging and communication. Much attention is being paid to the ultimate limits of this quantum technology. For example, it has already been shown that exotic quantum states can be used to measure or image with higher precision or higher resolution or lower radiated power than any conventional technologies, and proof-of-principle experiments demonstrating measurement precision below the standard quantum limit (shot noise) are just starting to appear. However, quantum technologies have another powerful advantage beyond pure sensing performance that may turn out to be more important in practical applications: the potential for building devices with lower size/weight/power (SWaP) and cost requirements than existing instruments. The organizers of Quantum Technology Applications Workshop (QTAW) have several goals: (1) Bring together sponsors, researchers, engineers and end users to help build a stronger quantum technology community; (2) Identify how quantum systems might improve the performance of practical devices in the near- to mid-term; and (3) Identify applications for which more long term investment is necessary to realize improved performance for realistic applications. To realize these goals, the QTAW II workshop included fifty scientists, engineers, managers and sponsors from academia, national laboratories, government and the private-sector. The agenda included twelve presentations, a panel discussion, several breaks for informal exchanges, and a written survey of participants. Topics included photon sources, optics and detectors, squeezed light, matter waves, atomic clocks and atom magnetometry. Corresponding applications included communication, imaging, optical interferometry, navigation, gravimetry, geodesy, biomagnetism, and explosives detection. Participants
Interface effect in coupled quantum wells
Hao, Ya-Fei
2014-06-28
This paper intends to theoretically investigate the effect of the interfaces on the Rashba spin splitting of two coupled quantum wells. The results show that the interface related Rashba spin splitting of the two coupled quantum wells is both smaller than that of a step quantum well which has the same structure with the step quantum well in the coupled quantum wells. And the influence of the cubic Dresselhaus spin-orbit interaction of the coupled quantum wells is larger than that of a step quantum well. It demonstrates that the spin relaxation time of the two coupled quantum wells will be shorter than that of a step quantum well. As for the application in the spintronic devices, a step quantum well may be better than the coupled quantum wells, which is mentioned in this paper.
Electromagnetic Probes: A Chronometer of Heavy Ion Collision
Sinha, Bikash
2010-11-23
I have known Predhiman for quite some time and I consider his friendship a great privilege. He along with some of his colleagues made the almost unique transition time to time from Quantum Electrodynamics of his (almost classical) electromagnetic plasma to Quantum Chromodynamics of quarks and gluons. Some of the papers are unique in the sense they surface up to the centre stage of the field of quarks and gluons giving us a new insight; the particular paper of Bannur and Kaw discussing the stability of quark gluon plasma is a particularly interesting one.I wish Predhiman the very best on this occasion and sincerely hope for a long vital and fruitful life that lies ahead.Interestingly enough this transition from QED (electromagnetic plasma) to QCD plasma (Quark Gluon Plasma) was motivated by consuming a very special kind of Indian soft nuts on Sunday afternoons, the consumers consisted of two persons, P. K. Kaw and Jitendra Parikh - some nuts!
Quantum interference in polyenes
Tsuji, Yuta; Hoffmann, Roald; Movassagh, Ramis; Datta, Supriyo
2014-12-14
The explicit form of the zeroth Green's function in the Hckel model, approximated by the negative of the inverse of the Hckel matrix, has direct quantum interference consequences for molecular conductance. We derive a set of rules for transmission between two electrodes attached to a polyene, when the molecule is extended by an even number of carbons at either end (transmission unchanged) or by an odd number of carbons at both ends (transmission turned on or annihilated). These prescriptions for the occurrence of quantum interference lead to an unexpected consequence for switches which realize such extension through electrocyclic reactions: for some specific attachment modes the chemically closed ring will be the ON position of the switch. Normally the signs of the entries of the Green's function matrix are assumed to have no physical significance; however, we show that the signs may have observable consequences. In particular, in the case of multiple probe attachments if coherence in probe connections can be arranged in some cases new destructive interference results, while in others one may have constructive interference. One such case may already exist in the literature.
Universal quantum computation in a semiconductor quantum wire network
Sau, Jay D.; Das Sarma, S.; Tewari, Sumanta
2010-11-15
Universal quantum computation (UQC) using Majorana fermions on a two-dimensional topological superconducting (TS) medium remains an outstanding open problem. This is because the quantum gate set that can be generated by braiding of the Majorana fermions does not include any two-qubit gate and also no single-qubit {pi}/8 phase gate. In principle, it is possible to create these crucial extra gates using quantum interference of Majorana fermion currents. However, it is not clear if the motion of the various order parameter defects (vortices, domain walls, etc.), to which the Majorana fermions are bound in a TS medium, can be quantum coherent. We show that these obstacles can be overcome using a semiconductor quantum wire network in the vicinity of an s-wave superconductor, by constructing topologically protected two-qubit gates and any arbitrary single-qubit phase gate in a topologically unprotected manner, which can be error corrected using magic-state distillation. Thus our strategy, using a judicious combination of topologically protected and unprotected gate operations, realizes UQC on a quantum wire network with a remarkably high error threshold of 0.14 as compared to 10{sup -3} to 10{sup -4} in ordinary unprotected quantum computation.
Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD
Du, Daping; El-Khadra, A. X.; Gottlieb, Steven; Kronfeld, A. S.; Laiho, J.; Lunghi, E.; Van de Water, R. S.; Zhou, Ran
2016-02-03
We study the exclusive semileptonic B-meson decays B→K(π)ℓ+ℓ-, B→K(π)νν¯, and B→πτν, computing observables in the Standard model using the recent lattice-QCD results for the underlying form factors from the Fermilab Lattice and MILC Collaborations. These processes provide theoretically clean windows into physics beyond the Standard Model because the hadronic uncertainties are now under good control. The resulting partially-integrated branching fractions for B→πμ+μ- and B→Kμ+μ- outside the charmonium resonance region are 1-2σ higher than the LHCb Collaboration's recent measurements, where the theoretical and experimental errors are commensurate. The combined tension is 1.7σ. Combining the Standard-Model rates with LHCb's measurements yields valuesmore » for the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements |Vtd|=7.45(69)×10-3, |Vts|=35.7(1.5)×10-3, and |Vtd/Vts|=0.201(20), which are compatible with the values obtained from neutral B(s)-meson oscillations and have competitive uncertainties. Alternatively, taking the CKM matrix elements from unitarity, we constrain new-physics contributions at the electroweak scale. Furthermore, the constraints on the Wilson coefficients Re(C9) and Re(C10) from B→πμ+μ- and B→Kμ+μ- are competitive with those from B→K*μ+μ-, and display a 2.0σ tension with the Standard Model. Our predictions for B→K(π)νν¯ and B→πτν are close to the current experimental limits.« less
Isovector and isoscalar tensor charges of the nucleon from lattice QCD
Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Cohen, Saul D.; Gupta, Rajan; Joseph, Anosh; Lin, Huey -Wen; Yoon, Boram
2015-11-10
Here, we present results for the isovector and flavor diagonal tensor charges gu–dT, guT, gdT, and gsT needed to probe novel tensor interactions at the TeV scale in neutron and nuclear β-decays and the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The lattice QCD calculations were done using nine ensembles of gauge configurations generated by the MILC collaboration using the HISQ action with 2+1+1 dynamical flavors. These ensembles span three lattice spacings a ≈ 0.06, 0.09 and 0.12 fm and three quark masses corresponding to the pion masses Mπ ≈ 130, 220 and 310 MeV.more » Using estimates from these ensembles, we quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, volume and light quark masses for the connected contributions. The final estimates of the connected nucleon (proton) tensor charge for the isovector combination is gu–dT = 1.020(76) in the MS¯ scheme at 2 GeV. The additional disconnected quark loop contributions needed for the flavor-diagonal matrix elements are calculated using a stochastic estimator employing the truncated solver method with the all-mode-averaging technique. We find that the size of the disconnected contribution is smaller than the statistical error in the connected contribution. This allows us to bound the disconnected contribution and include it as an additional uncertainty in the flavor-diagonal charges. After a continuum extrapolation, we find guT = 0.774(66), gdT = –0.233(28) and gu+dT = 0.541(67). The strangeness tensor charge, that can make a significant contribution to the neutron EDM due to the large ratio ms/mu,d, is gsT = 0.008(9) in the continuum limit.« less
Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD
Du, Daping; El-Khadra, A. X.; Gottlieb, Steven; Kronfeld, A. S.; Laiho, J.; Lunghi, E.; Van de Water, R. S.; Zhou, Ran
2015-10-08
We study the exclusive semileptonic B-meson decays B→K(π)ℓ^{+}ℓ^{-}, B→K(π)νν¯, and B→πτν, computing observables in the Standard model using the recent lattice-QCD results for the underlying form factors from the Fermilab Lattice and MILC Collaborations. These processes provide theoretically clean windows into physics beyond the Standard Model because the hadronic uncertainties are now under good control. The resulting partially-integrated branching fractions for B→πμ^{+}μ^{-} and B→Kμ^{+}μ^{-} outside the charmonium resonance region are 1-2σ higher than the LHCb Collaboration's recent measurements, where the theoretical and experimental errors are commensurate. The combined tension is 1.7σ. Combining the Standard-Model rates with LHCb's measurements yields values for the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements |V_{td}|=7.45(69)×10^{-3}, |V_{ts}|=35.7(1.5)×10^{-3}, and |V_{td}/V_{ts}|=0.201(20), which are compatible with the values obtained from neutral B_{(s)}-meson oscillations and have competitive uncertainties. Alternatively, taking the CKM matrix elements from unitarity, we constrain new-physics contributions at the electroweak scale. Furthermore, the constraints on the Wilson coefficients Re(C_{9}) and Re(C_{10}) from B→πμ^{+}μ^{-} and B→Kμ^{+}μ^{-} are competitive with those from B→K*μ^{+}μ^{-}, and display a 2.0σ tension with the Standard Model. Our predictions for B→K(π)νν¯ and B→πτν are close to the current experimental limits.
Heavy-Quark Associated Production with One Hard Photon at Hadron Colliders
Hartanto, Heribertus Bayu
2013-01-01
We present the calculation of heavy-quark associated production with a hard photon at hadron colliders, namely $pp(p\\bar p) \\rightarrow Q\\bar Q\\gam +X$ (for $Q=t,b$), at Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For $t\\bar t\\gam$ production we observe a sizeable reduction of the renormalization and factorization scale dependence when the NLO QCD corrections are included, while for $b\\bar b\\gam$ production a considerable scale dependence still persists at NLO in QCD. This is consistent with what emerges in similar processes involving $b$ quarks and vector bosons and we explain its origin in detail. For $b\\bar b\\gam$ production we study both the case in which at least one $b$ jet and the case in which at least two $b$ jets are observed. We perform the $b\\bar b\\gam$ calculation using the Four Flavor Number Scheme (4FNS) and compare the case where at least one $b$ jet is observed with the corresponding results from the Five Flavor Number Scheme (5FNS) calculation. Finally we compare our results for $p\\bar p \\rightarrow \\gam+b+X$ with the Tevatron data.
Evolving images of the proton: Hadron physics over the past 40 years
Pennington, Michael R.
2016-04-05
Once upon a time, the world was simple: the proton contained three quarks, two ups and a down. How these give the proton its mass and its spin seemed obvious. Over the past 40 years the proton has become more complicated, and how even these most obvious of its properties is explained in a universe of quarks, antiquarks and gluons remains a challenge. That this should be so should come as no surprise. Quantum chromodynamics, the theory of the strong interaction, is seemingly simple, and its consequences are straightforward in the domain of hard scattering where perturbation theory applies. However,more » the beauty of the hadron world is its diversity. The existence of hadrons, their properties, and their binding into nuclei do not appear in the Lagrangian of QCD. They all emerge as a result of its strong coupling. Strong coupling QCD creates complex phenomena, much richer than known 40 years ago: a richness that ensures colour confinement and accounts for more than 95% of the mass of the visible Universe. How strong coupling QCD really works requires a synergy between experiment and theory. Furthermore, a very personal view of these fascinating developments in cold QCD is presented.« less
Study of Jet Transverse Momentum and Jet Rapidity Dependence on Dijet Azimuthal Decorrelations
Chakravarthula, Kiran
2012-01-01
In a collision experiment involving highly energetic particles such as hadrons, processes at high momentum transfers can provide information useful for many studies involving Quantum Chromodynamics (QCD). One way of analyzing these interactions is through angular distributions. In hadron-hadron collisions, the angular distribution between the two leading jets with the largest transverse momentum (p_{T} ) is affected by the production of additional jets. While soft radiation causes small differences in the azimuthal angular distribution of the two leading jets produced in a collision event, additional hard jets produced in the event have more pronounced influence on the distribution of the two leading jets produced in the collision. Thus, the dijet azimuthal angular distribution can serve as a variable that can be used to study the transition from soft to hard QCD processes in a collision event. This dissertation presents a triple-differential study involving the azimuthal angular distribution and the jet transverse momenta, and jet rapidities of the first two leading jets. The data used for this research are obtained from proton-antiproton (p$\\bar{p}$) collisions occurring at a center of mass energy of 1.96TeV, using the DØ detector in Run II of the Tevatron Collider at the Fermi National Accelerator Laboratory (FNAL) in Illinois, USA. Comparisons are made to perturbative QCD (_{p}QCD) predictions at next-to-leading order (NLO).
Higgs boson gluon-fusion production beyond threshold in N^{3}LO QCD
Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard
2015-03-18
In this study, we compute the gluon fusion Higgs boson cross-section at N^{3}LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N^{3}LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N^{3}LO in perturbative QCD.
Gottlieb, S.; Krasnitz, A. . Dept. of Physics); Heller, U.M.; Kennedy, A.D. . Supercomputer Computations Research Inst.); Kogut, J.B. . Dept. of Physics); Liu, W. ); Renken, R.L. (University of Central F
1991-01-01
Lattice QCD with 2 light staggered quark flavours is being simulated on a 16{sup 3} {times} 8 lattice to study the transition from hadronic matter to a quark gluon plasma. We have completed runs at m{sub q} = 0.0125 and are extending this to m{sub q} = 0.00625. We also examine the addition of a non-dynamical strange'' quark. Thermodynamic order parameters are being measured across the transition and further into the plasma phase, as are various screening lengths. No evidence for a first order transition is seen, and we estimate the transition temperature to be {Tc} = 143(7)MeV.
Gottlieb, S.; Krasnitz, A.; Heller, U.M.; Kennedy, A.D.; Kogut, J.B.; Liu, W.; Renken, R.L.; Sinclair, D.K.; Sugar, R.L.; Toussaint, D.; Wang, K.C.
1991-12-31
Lattice QCD with 2 light staggered quark flavours is being simulated on a 16{sup 3} {times} 8 lattice to study the transition from hadronic matter to a quark gluon plasma. We have completed runs at m{sub q} = 0.0125 and are extending this to m{sub q} = 0.00625. We also examine the addition of a non-dynamical ``strange`` quark. Thermodynamic order parameters are being measured across the transition and further into the plasma phase, as are various screening lengths. No evidence for a first order transition is seen, and we estimate the transition temperature to be {Tc} = 143(7)MeV.
Renormalization-group analysis of the validity of staggered-fermion QCD with the fourth-root recipe
Shamir, Yigal [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978 Tel Aviv (Israel)
2007-03-01
I develop a renormalization-group blocking framework for lattice QCD with staggered fermions. Under plausible, and testable assumptions, I then argue that the fourth-root recipe used in numerical simulations is valid in the continuum limit. The taste-symmetry violating terms, which give rise to nonlocal effects in the fourth-root theory when the lattice spacing is nonzero, vanish in the continuum limit. A key role is played by reweighted theories that are local and renormalizable on the one hand, and that approximate the fourth-root theory better and better as the continuum limit is approached on the other hand.
Z-boson production in association with a jet at next-to-next-to-leading order in perturbative QCD
Boughezal, Radja; Campbell, John M.; Ellis, R. Keith; Focke, Christfried; Giele, Walter T.; Liu, Xiaohui; Petriello, Frank
2016-04-14
Here, we present the first complete calculation of Z-boson production in association with a jet in hadronic collisions through next-to-next-to-leading order in perturbative QCD. Our computation uses the recently proposed N-jettiness subtraction scheme to regulate the infrared divergences that appear in the real-emission contributions. We present phenomenological results for 13 TeV proton-proton collisions with fully realistic fiducial cuts on the final-state particles. The remaining theoretical uncertainties after the inclusion of our calculations are at the percent level, making the Z+jet channel ready for precision studies at the LHC run II.
Two-Loop QCD Amplitude for gg{yields}h, H in the Minimal Supersymmetric Standard Model
Anastasiou, Charalampos; Beerli, Stefan; Daleo, Alejandro
2008-06-20
We present the two-loop QCD amplitude for the interaction of two gluons and a CP-even Higgs boson in the minimal supersymmetric standard model (MSSM). We apply a novel numerical method for the evaluation of Feynman diagrams with infrared, ultraviolet, and threshold singularities. We discuss subtleties in the ultraviolet renormalization of the amplitude with conventional dimensional regularization, dimensional reduction, and the four dimensional helicity scheme. Finally, we show numerical results for scenarios of supersymmetry breaking with a rather challenging phenomenology in which the Higgs signal in the MSSM is suppressed in comparison to the standard model.
Phases of QCD: Summary of the Rutgers Long Range Plan Town Meeting, January 12-14, 2007
Jacobs, Peter; Kharzeev, Dmitri; Muller, Berndt; Nagle, Jamie; Rajagopal, Krishna; Vigdor, Steve
2007-05-14
This White Paper summarizes the outcome of the Town Meeting on Phases of QCD that took place January 12-14, 2007 at Rutgers University, as part of the NSAC 2007 Long Range Planning process. The meeting was held in conjunction with the Town Meeting on Hadron Structure, including a full day of joint plenary sessions of the two meetings. Appendix A.1 contains the meeting agenda. This Executive Summary presents the prioritized recommendations that were determined at the meeting. Subsequent chapters present the essential background to the recommendations. While this White Paper is not a scholarly article and contains few references, it is intended to provide the non-expert reader
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
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The Collider Detector at Fermilab (CDF) is a Tevatron experiment at Fermilab. The Tevatron, a powerful particle accelerator, accelerates protons and antiprotons close to the speed of light, and then makes them collide head-on inside the CDF detector. The CDF detector is used to study the products of such collisions. The CDF Physics Group at Fermilab is organized into six working groups, each with a specific focus. The QCD group studies the properties of the strong interaction. Their public web page makes data and numerous figures available from both CDF Runs I and II.
Quantum random number generator
Pooser, Raphael C.
2016-05-10
A quantum random number generator (QRNG) and a photon generator for a QRNG are provided. The photon generator may be operated in a spontaneous mode below a lasing threshold to emit photons. Photons emitted from the photon generator may have at least one random characteristic, which may be monitored by the QRNG to generate a random number. In one embodiment, the photon generator may include a photon emitter and an amplifier coupled to the photon emitter. The amplifier may enable the photon generator to be used in the QRNG without introducing significant bias in the random number and may enable multiplexing of multiple random numbers. The amplifier may also desensitize the photon generator to fluctuations in power supplied thereto while operating in the spontaneous mode. In one embodiment, the photon emitter and amplifier may be a tapered diode amplifier.
Flavored quantum Boltzmann equations
Cirigliano, Vincenzo; Lee, Christopher; Ramsey-Musolf, Michael J.; Tulin, Sean [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States); Center for Theoretical Physics, University of California, and Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, California, 94720 (United States); Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin, 53706 (United States) and Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California, 91125 (United States); Theory Group, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)
2010-05-15
We derive from first principles, using nonequilibrium field theory, the quantum Boltzmann equations that describe the dynamics of flavor oscillations, collisions, and a time-dependent mass matrix in the early universe. Working to leading nontrivial order in ratios of relevant time scales, we study in detail a toy model for weak-scale baryogenesis: two scalar species that mix through a slowly varying time-dependent and CP-violating mass matrix, and interact with a thermal bath. This model clearly illustrates how the CP asymmetry arises through coherent flavor oscillations in a nontrivial background. We solve the Boltzmann equations numerically for the density matrices, investigating the impact of collisions in various regimes.
Phase space quantum mechanics - Direct
Nasiri, S.; Sobouti, Y.; Taati, F.
2006-09-15
Conventional approach to quantum mechanics in phase space (q,p), is to take the operator based quantum mechanics of Schroedinger, or an equivalent, and assign a c-number function in phase space to it. We propose to begin with a higher level of abstraction, in which the independence and the symmetric role of q and p is maintained throughout, and at once arrive at phase space state functions. Upon reduction to the q- or p-space the proposed formalism gives the conventional quantum mechanics, however, with a definite rule for ordering of factors of noncommuting observables. Further conceptual and practical merits of the formalism are demonstrated throughout the text.
Quantum Gibbs ensemble Monte Carlo
Fantoni, Riccardo; Moroni, Saverio
2014-09-21
We present a path integral Monte Carlo method which is the full quantum analogue of the Gibbs ensemble Monte Carlo method of Panagiotopoulos to study the gas-liquid coexistence line of a classical fluid. Unlike previous extensions of Gibbs ensemble Monte Carlo to include quantum effects, our scheme is viable even for systems with strong quantum delocalization in the degenerate regime of temperature. This is demonstrated by an illustrative application to the gas-superfluid transition of {sup 4}He in two dimensions.
Quantum Field Theory & Gravity
U.S. Department of Energy (DOE) all webpages (Extended Search)
Quantum Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505) 667-5657 Email Quantum Field Theory and Gravity at Los Alamos The HEP effort at Los Alamos in this area is actively pursing a number of questions in this area. What is the final state of complete gravitational collapse? What happens at the event horizon? What is dark energy? How did the
T-QUAKE Quantum Mechanical Microchip
U.S. Department of Energy (DOE) all webpages (Extended Search)
Principal application T-QUAKE Quantum Mechanical Microchip The quantum world defies intuition. One of its axioms, the Heisenberg Uncertainty Principle, states that any attempt to measure the position or momentum of a quantum object changes the object itself. Historically, this principle was viewed as a hindrance by scientists trying to examine quantum particles. But the same quantum effects that make them difficult to measure have long been of interest to the cryptography and intelligence
The Common Elements of Atomic and Hadronic Physics
Brodsky, Stanley J.
2015-02-26
Atomic physics and hadronic physics are both governed by the Yang Mills gauge theory Lagrangian; in fact, Abelian quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics can provide important insight into hadronic eigenstates in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of frame-independent light-front relativistic equations of motion consistent with light-front holography which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The production of antihydrogen in flight can provide important insight into the dynamics of hadron production in QCD at the amplitude level. The renormalization scale for the running coupling is unambiguously set in QED; an analogous procedure sets the renormalization scales in QCD, leading to scheme-independent scale-fixed predictions. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, the quark-interchange process and light-front quantization have important applicants for atomic physics and photon science, especially in the relativistic domain.
Scalable quantum computer architecture with coupled donor-quantum dot qubits
Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey
2014-08-26
A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.
CdSe Quantum-Dot-Sensitized Solar Cell with ~100% Internal Quantum...
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CdSe Quantum-Dot-Sensitized Solar Cell with 100% Internal Quantum Efficiency Citation Details In-Document Search Title: CdSe Quantum-Dot-Sensitized Solar Cell with 100% Internal ...
Dumitru, Adrian; Jalilian-Marian, Jamal
2010-10-01
Present knowledge of QCD n-point functions of Wilson lines at high energies is rather limited. In practical applications, it is therefore customary to factorize higher n-point functions into products of two-point functions (dipoles) which satisfy the Balitsky-Kovchegov-evolution equation. We employ the Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner formalism to derive explicit evolution equations for the 4- and 6-point functions of fundamental Wilson lines and show that if the Gaussian approximation is carried out before the rapidity evolution step is taken, then many leading order N{sub c} contributions are missed. Our evolution equations could specifically be used to improve calculations of forward dijet angular correlations, recently measured by the STAR Collaboration in deuteron-gold collisions at the RHIC collider. Forward dijets in proton-proton collisions at the LHC probe QCD evolution at even smaller light-cone momentum fractions. Such correlations may provide insight into genuine differences between the Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner and Balitsky-Kovchegov approaches.
QCD Corrections to e{sup +}e{sup -}{yields}J/{psi}+gg at B Factories
Ma Yanqing; Zhang Yujie; Chao Kuangta
2009-04-24
In heavy quarkonium production, the measured ratio R{sub cc}={sigma}[J/{psi}+cc+X]/{sigma}[J/{psi}+X] at B factories is much larger than existing theoretical predictions. To clarify this discrepancy, in nonrelativistic QCD we find the next-to-leading-order (NLO) QCD correction to e{sup +}e{sup -}{yields}J/{psi}+gg can enhance the cross section by about 20%. Together with the calculated NLO result for e{sup +}e{sup -}{yields}J/{psi}+cc, we show that the NLO corrections can significantly improve the fit to the ratio R{sub cc}. The effects of leading logarithm resummation near the end point on the J/{psi} momentum distribution and total cross section are also considered. Comparison of the calculated cross section for e{sup +}e{sup -}{yields}J/{psi}+gg with the observed cross section for e{sup +}e{sup -}{yields}J/{psi}+non-(cc) is expected to provide unique information on the issue of color-octet contributions.
Concurrence of quasipure quantum states
Mintert, Florian; Buchleitner, Andreas
2005-07-15
We derive an analytic approximation for the concurrence of weakly mixed bipartite quantum states--typical objects in state of the art experiments. This approximation is shown to be a lower bound of the concurrence of arbitrary states.
Quantum fluctuations in beam dynamics.
Kim, K.-J.
1998-06-04
Quantum effects could become important for particle and photon beams used in high-luminosity and high brightness applications in the current and next generation accelerators and radiation sources. This paper is a review of some of these effects.
Timelike Momenta In Quantum Electrodynamics
DOE R&D Accomplishments [OSTI]
Brodsky, S. J.; Ting, S. C. C.
1965-12-01
In this note we discuss the possibility of studying the quantum electrodynamics of timelike photon propagators in muon or electron pair production by incident high energy muon or electron beams from presently available proton or electron accelerators.
Few Electron Quantum Dot coupling ...
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Electron Quantum Dot coupling to Donor Implanted Electron Spins Martin Rudolph1. P. Harvey-Collard12, E. Nielson1, J.K. Gamble1, R. Muller1, T. Jacobson1, G. Ten-Eyck1, J. ...
Santa Fe New Mexican: For cybersecurity, in quantum encryption...
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For cybersecurity, in quantum encryption we trust Santa Fe New Mexican: For cybersecurity, in quantum encryption we trust Los Alamos physicists developed a quantum random number...
Promising future of quantum dots explored in conference
U.S. Department of Energy (DOE) all webpages (Extended Search)
Promising future of quantum dots explored Promising future of quantum dots explored in conference Researchers are gathering to reflect on two decades of quantum dot research at a ...
Nanoscale engineering boosts performance of quantum dot light...
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Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission ...
The Quantum Way of Sensing | Argonne Leadership Computing Facility
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quantum optics and spintronics. He counts as a pioneer in the field of solid state spin quantum physics and has explored applications in photonics, spintronics, quantum computing ...
DOE Science Showcase - Quantum Dots | OSTI, US Dept of Energy...
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For additional information, see the OSTI Catalogue of Collections. RefreshLine.png Additional Resources Quantum dot, Wikipedia Quantum dot solar cell, Wikipedia Los Alamos Quantum ...
Deformation Quantization: Quantum Mechanic Lives and Works in...
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It has been useful in describing quantum flows in: quantum optics; nuclear physics; ... Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 73 NUCLEAR PHYSICS AND ...
Isovector and isoscalar tensor charges of the nucleon from lattice QCD
Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Cohen, Saul D.; Gupta, Rajan; Joseph, Anosh; Lin, Huey -Wen; Yoon, Boram
2015-11-10
Here, we present results for the isovector and flavor diagonal tensor charges g^{u–d}_{T}, g^{u}_{T}, g^{d}_{T}, and g^{s}_{T} needed to probe novel tensor interactions at the TeV scale in neutron and nuclear β-decays and the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The lattice QCD calculations were done using nine ensembles of gauge configurations generated by the MILC collaboration using the HISQ action with 2+1+1 dynamical flavors. These ensembles span three lattice spacings a ≈ 0.06, 0.09 and 0.12 fm and three quark masses corresponding to the pion masses M_{π} ≈ 130, 220 and 310 MeV. Using estimates from these ensembles, we quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, volume and light quark masses for the connected contributions. The final estimates of the connected nucleon (proton) tensor charge for the isovector combination is g^{u–d}_{T} = 1.020(76) in the MS¯ scheme at 2 GeV. The additional disconnected quark loop contributions needed for the flavor-diagonal matrix elements are calculated using a stochastic estimator employing the truncated solver method with the all-mode-averaging technique. We find that the size of the disconnected contribution is smaller than the statistical error in the connected contribution. This allows us to bound the disconnected contribution and include it as an additional uncertainty in the flavor-diagonal charges. After a continuum extrapolation, we find g^{u}_{T} = 0.774(66), g^{d}_{T} = –0.233(28) and g^{u+d}_{T} = 0.541(67). The strangeness tensor charge, that can make a significant contribution to the neutron EDM due to the large ratio m_{s}/m_{u,d}, is g^{s}_{T} = 0.008(9) in the continuum limit.
Convex polytopes and quantum separability
Holik, F.; Plastino, A.
2011-12-15
We advance a perspective of the entanglement issue that appeals to the Schlienz-Mahler measure [Phys. Rev. A 52, 4396 (1995)]. Related to it, we propose a criterium based on the consideration of convex subsets of quantum states. This criterium generalizes a property of product states to convex subsets (of the set of quantum states) that is able to uncover an interesting geometrical property of the separability property.
Spagnolo, Nicolo; Sciarrino, Fabio; De Martini, Francesco
2010-09-15
We show that the quantum states generated by universal optimal quantum cloning of a single photon represent a universal set of quantum superpositions resilient to decoherence. We adopt the Bures distance as a tool to investigate the persistence of quantum coherence of these quantum states. According to this analysis, the process of universal cloning realizes a class of quantum superpositions that exhibits a covariance property in lossy configuration over the complete set of polarization states in the Bloch sphere.
Quantum well multijunction photovoltaic cell
Chaffin, R.J.; Osbourn, G.C.
1983-07-08
A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.
Quantum well multijunction photovoltaic cell
Chaffin, Roger J.; Osbourn, Gordon C.
1987-01-01
A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.
Finite groups and quantum physics
Kornyak, V. V.
2013-02-15
Concepts of quantum theory are considered from the constructive 'finite' point of view. The introduction of a continuum or other actual infinities in physics destroys constructiveness without any need for them in describing empirical observations. It is shown that quantum behavior is a natural consequence of symmetries of dynamical systems. The underlying reason is that it is impossible in principle to trace the identity of indistinguishable objects in their evolution-only information about invariant statements and values concerning such objects is available. General mathematical arguments indicate that any quantum dynamics is reducible to a sequence of permutations. Quantum phenomena, such as interference, arise in invariant subspaces of permutation representations of the symmetry group of a dynamical system. Observable quantities can be expressed in terms of permutation invariants. It is shown that nonconstructive number systems, such as complex numbers, are not needed for describing quantum phenomena. It is sufficient to employ cyclotomic numbers-a minimal extension of natural numbers that is appropriate for quantum mechanics. The use of finite groups in physics, which underlies the present approach, has an additional motivation. Numerous experiments and observations in the particle physics suggest the importance of finite groups of relatively small orders in some fundamental processes. The origin of these groups is unclear within the currently accepted theories-in particular, within the Standard Model.
ASCR Workshop on Quantum Computing for Science
Aspuru-Guzik, Alan; Van Dam, Wim; Farhi, Edward; Gaitan, Frank; Humble, Travis; Jordan, Stephen; Landahl, Andrew J; Love, Peter; Lucas, Robert; Preskill, John; Muller, Richard P.; Svore, Krysta; Wiebe, Nathan; Williams, Carl
2015-06-01
This report details the findings of the DOE ASCR Workshop on Quantum Computing for Science that was organized to assess the viability of quantum computing technologies to meet the computational requirements of the DOE’s science and energy mission, and to identify the potential impact of quantum technologies. The workshop was held on February 17-18, 2015, in Bethesda, MD, to solicit input from members of the quantum computing community. The workshop considered models of quantum computation and programming environments, physical science applications relevant to DOE's science mission as well as quantum simulation, and applied mathematics topics including potential quantum algorithms for linear algebra, graph theory, and machine learning. This report summarizes these perspectives into an outlook on the opportunities for quantum computing to impact problems relevant to the DOE’s mission as well as the additional research required to bring quantum computing to the point where it can have such impact.
Study of the nature of the confinement in the GlueX experiment
Somov, S.; Berdnikov, Vladmir; Tolstukhin, Ivan; Somov, Alexander S.
2015-11-01
Confinement is a fundamental property of quantum chromodynamics (QCD) associated with the unique role of the gluonic field responsible for binding quarks in hadrons. Understanding the role of gluons in the confinement of quarks is one of the most tantalizing topics in modern particle physics to be explored. The new experiment GlueX has been recently constructed at Jefferson Lab. The experiment was designed to search for hybrid mesons with exotic quantum numbers using a beam of linearly polarized photons incident on a liquid hydrogen target. The spectrum of these states and their mass splitting from normal mesons may yield information on confinement. In addition, these observations in combination with detailed chromodynamics calculations such as on the Lattice can provide important tests for our understanding of the role of gluons. The production of exotic mesons is expected to be enhanced in p interactions, where the experimental data is very limited. We present the description of the GlueX detector, beam line, and first results of the commissioning with photon beam.
History dependent quantum random walks as quantum lattice gas automata
Shakeel, Asif E-mail: dmeyer@math.ucsd.edu Love, Peter J. E-mail: dmeyer@math.ucsd.edu; Meyer, David A. E-mail: dmeyer@math.ucsd.edu
2014-12-15
Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.