Science.gov

Sample records for density lattice qcd

  1. LATTICE QCD AT FINITE DENSITY.

    SciTech Connect

    SCHMIDT, C.

    2006-07-23

    I discuss different approaches to finite density lattice QCD. In particular, I focus on the structure of the phase diagram and discuss attempts to determine the location of the critical end-point. Recent results on the transition line as function of the chemical potential (T{sub c}({mu}{sub q})) are reviewed. Along the transition line, hadronic fluctuations have been calculated; which can be used to characterize properties of the Quark Gluon plasma and eventually can also help to identify the location of the critical end-point in the QCD phase diagram on the lattice and in heavy ion experiments. Furthermore, I comment on the structure of the phase diagram at large {mu}{sub q}.

  2. Lattice QCD and High Baryon Density State

    SciTech Connect

    Nagata, Keitaro; Nakamura, Atsushi; Motoki, Shinji; Nakagawa, Yoshiyuki; Saito, Takuya

    2011-10-21

    We report our recent studies on the finite density QCD obtained from lattice QCD simulation with clover-improved Wilson fermions of two flavor and RG-improved gauge action. We approach the subject from two paths, i.e., the imaginary and chemical potentials.

  3. LATTICE QCD AT FINITE TEMPERATURE AND DENSITY.

    SciTech Connect

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

    2004-02-24

    With the operation of the RHIC heavy ion program, the theoretical understanding of QCD at finite temperature and density has become increasingly important. Though QCD at finite temperature has been extensively studied using lattice Monte-Carlo simulations over the past twenty years, most physical questions relevant for RHIC (and future) heavy ion experiments remain open. In lattice QCD at finite temperature and density there have been at least two major advances in recent years. First, for the first time calculations of real time quantities, like meson spectral functions have become available. Second, the lattice study of the QCD phase diagram and equation of state have been extended to finite baryon density by several groups. Both issues were extensively discussed in the course of the workshop. A real highlight was the study of the QCD phase diagram in (T, {mu})-plane by Z. Fodor and S. Katz and the determination of the critical end-point for the physical value of the pion mass. This was the first time such lattice calculations at, the physical pion mass have been performed. Results by Z Fodor and S. Katz were obtained using a multi-parameter re-weighting method. Other determinations of the critical end point were also presented, in particular using a Taylor expansion around {mu} = 0 (Bielefeld group, Ejiri et al.) and using analytic continuation from imaginary chemical potential (Ph. de Forcrand and O. Philipsen). The result based on Taylor expansion agrees within errors with the new prediction of Z. Fodor and S. Katz, while methods based on analytic continuation still predict a higher value for the critical baryon density. Most of the thermodynamics studies in full QCD (including those presented at this workshop) have been performed using quite coarse lattices, a = 0.2-0.3 fm. Therefore one may worry about cutoff effects in different thermodynamic quantities, like the transition temperature T{sub tr}. At the workshop U. Heller presented a study of the transition

  4. Transverse momentum dependent quark densities from Lattice QCD

    SciTech Connect

    Bernhard Musch,Philipp Hagler,John Negele,Andreas Schafer

    2011-10-01

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. We discuss the basic concepts of the method, including renormalization of the gauge link. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.

  5. Transverse momentum dependent quark densities from Lattice QCD

    SciTech Connect

    Musch, B. U.; Haegler, Ph.; Negele, J. W.; Schaefer, A.

    2011-10-24

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. We discuss the basic concepts of the method, including renormalization of the gauge link. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.

  6. Lattice QCD

    SciTech Connect

    Bornyakov, V.G.

    2005-06-01

    Possibilities that are provided by a lattice regularization of QCD for studying nonperturbative properties of QCD are discussed. A review of some recent results obtained from computer calculations in lattice QCD is given. In particular, the results for the QCD vacuum structure, the hadron mass spectrum, and the strong coupling constant are considered.

  7. Transverse momentum dependent quark densities from Lattice QCD

    SciTech Connect

    Bernhard Musch,Philipp Hagler,John Negele,Andreas Schafer

    2011-02-01

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

  8. Phase transition in finite density and temperature lattice QCD

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Chen, Ying; Gong, Ming; Liu, Chuan; Liu, Yu-Bin; Liu, Zhao-Feng; Ma, Jian-Ping; Meng, Xiang-Fei; Zhang, Jian-Bo

    2015-06-01

    We investigate the behavior of the chiral condensate in lattice QCD at finite temperature and finite chemical potential. The study was done using two flavors of light quarks and with a series of β and ma at the lattice size 24 × 122 × 6. The calculation was done in the Taylor expansion formalism. We are able to calculate the first and second order derivatives of ≤ft< {\\bar{\\psi} \\psi } \\right> in both isoscalar and isovector channels. With the first derivatives being small, we find that the second derivatives are sizable close to the phase transition and that the magnitude of \\bar{\\psi} \\psi decreases under the influence of finite chemical potential in both channels. Supported by National Natural Science Foundation of China (11335001, 11105153, 11405178), Projects of International Cooperation and Exchanges NSFC (11261130311)

  9. THERMODYNAMICS OF TWO-FLAVOR LATTICE QCD WITH AN IMPROVED WILSON QUARK ACTION AT NON-ZERO TEMPERATURE AND DENSITY.

    SciTech Connect

    MAEZAWA,Y.; AOKI, S.; EJIRI, S.; HATSUDA, T.; ISHII, N.; KANAYA, K.; UKITA, N.

    2006-11-14

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

  10. Complex spectrum of finite-density lattice QCD with static quarks at strong coupling

    NASA Astrophysics Data System (ADS)

    Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

    2016-05-01

    We calculate the spectrum of transfer matrix eigenvalues associated with Polyakov loops in finite-density lattice QCD with static quarks. These eigenvalues determine the spatial behavior of Polyakov loop correlation functions. Our results are valid for all values of the gauge coupling in 1 +1 dimensions and in the strong-coupling region for any number of dimensions. When the quark chemical potential μ is nonzero, the spatial transfer matrix Ts is non-Hermitian. The appearance of complex eigenvalues in Ts is a manifestation of the sign problem in finite-density QCD. The invariance of finite-density QCD under the combined action of charge conjugation C and complex conjugation K implies that the eigenvalues of Ts are either real or part of a complex pair. Calculation of the spectrum confirms the existence of complex pairs in much of the temperature-chemical potential plane. Many features of the spectrum for static quarks are determined by a particle-hole symmetry. For μ that is small compared to the quark mass M , we typically find real eigenvalues for the lowest-lying states. At somewhat larger values of μ , pairs of eigenvalues may form complex-conjugate pairs, leading to damped oscillatory behavior in Polyakov loop correlation functions. However, near μ =M , the low-lying spectrum becomes real again. This is a direct consequence of the approximate particle-hole symmetry at μ =M for heavy quarks. This behavior of the eigenvalues should be observable in lattice simulations and can be used as a test of lattice algorithms. Our results provide independent confirmation of results we have previously obtained in Polyakov-Nambu-Jona-Lasinio models using complex saddle points.

  11. RECENT LATTICE RESULTS ON FINITE TEMPERATURE AND DENSITY QCD, PART 1.

    SciTech Connect

    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.

  12. Progress in lattice QCD

    SciTech Connect

    Andreas S. Kronfeld

    2002-09-30

    After reviewing some of the mathematical foundations and numerical difficulties facing lattice QCD, I review the status of several calculations relevant to experimental high-energy physics. The topics considered are moments of structure functions, which may prove relevant to search for new phenomena at the LHC, and several aspects of flavor physics, which are relevant to understanding CP and flavor violation.

  13. Lattice simulation study of SU(2) QCD with a nonzero baryon density

    NASA Astrophysics Data System (ADS)

    Braguta, V. V.; Kotov, A. Yu.; Nikolaev, A. A.; Valgushev, S. N.

    2015-06-01

    The lattice simulation of SU(2) QCD with two quark dynamical flavors and a nonzero baryon chemical potential has been performed. The dependence of the Polyakov loop and chiral condensate on the chemical potential has been studied. It has been shown that the chemical potential reduces the chiral condensate, thus weakening the breaking of the chiral symmetry.

  14. Lattice QCD in rotating frames.

    PubMed

    Yamamoto, Arata; Hirono, Yuji

    2013-08-23

    We formulate lattice QCD in rotating frames to study the physics of QCD matter under rotation. We construct the lattice QCD action with the rotational metric and apply it to the Monte Carlo simulation. As the first application, we calculate the angular momenta of gluons and quarks in the rotating QCD vacuum. This new framework is useful to analyze various rotation-related phenomena in QCD. PMID:24010426

  15. Lattice QCD for parallel computers

    NASA Astrophysics Data System (ADS)

    Quadling, Henley Sean

    Lattice QCD is an important tool in the investigation of Quantum Chromodynamics (QCD). This is particularly true at lower energies where traditional perturbative techniques fail, and where other non-perturbative theoretical efforts are not entirely satisfactory. Important features of QCD such as confinement and the masses of the low lying hadronic states have been demonstrated and calculated in lattice QCD simulations. In calculations such as these, non-lattice techniques in QCD have failed. However, despite the incredible advances in computer technology, a full solution of lattice QCD may still be in the too-distant future. Much effort is being expended in the search for ways to reduce the computational burden so that an adequate solution of lattice QCD is possible in the near future. There has been considerable progress in recent years, especially in the research of improved lattice actions. In this thesis, a new approach to lattice QCD algorithms is introduced, which results in very significant efficiency improvements. The new approach is explained in detail, evaluated and verified by comparing physics results with current lattice QCD simulations. The new sub-lattice layout methodology has been specifically designed for current and future hardware. Together with concurrent research into improved lattice actions and more efficient numerical algorithms, the very significant efficiency improvements demonstrated in this thesis can play an important role in allowing lattice QCD researchers access to much more realistic simulations. The techniques presented in this thesis also allow ambitious QCD simulations to be performed on cheap clusters of commodity computers.

  16. Introduction to lattice QCD

    SciTech Connect

    Gupta, R.

    1998-12-31

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

  17. Predictions from lattice QCD

    SciTech Connect

    Kronfeld, A.S.; Allison, I.F.; Aubin, C.; Bernard, C.; Davies, C.T.H.; DeTar, C.; Di Pierro, M.; Freeland, E.D.; Gottlieb, Steven; Gray, A.; Gregor, E.; Heller, U.M.; Hetrick, J.E.; El-Khadra, Aida X.; Levkova, L.; Mackenzie, P.B.; Maresca, F.; Menscher, D.; Nobes, M.; Okamoto, M.; Oktay, M.B.; /Fermilab /Glasgow U. /Columbia U. /Washington U., St. Louis /Utah U. /DePaul U. /Art Inst. of Chicago /Indiana U. /Ohio State U. /Arizona U. /APS, New York /U. Pacific, Stockton /Illinois U., Urbana /Cornell U., LEPP /Simon Fraser U. /UC, Santa Barbara

    2005-09-01

    In the past year, we calculated with lattice QCD three quantities that were unknown or poorly known. They are the q{sup 2} dependence of the form factor in semileptonic D {yields} K/{nu} decay, the decay constant of the D meson, and the mass of the B{sub c} meson. In this talk, we summarize these calculations, with emphasis on their (subsequent) confirmation by experiments.

  18. Nuclear reactions from lattice QCD

    SciTech Connect

    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.

  19. Nuclear reactions from lattice QCD

    DOE PAGESBeta

    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

  20. Lattice QCD at finite temperature and density in the phase-quenched approximation.

    SciTech Connect

    Kogut, J. B.; Sinclair, D. K.; High Energy Physics; Univ Maryland

    2008-06-01

    QCD at a finite quark-number chemical potential {mu} has a complex fermion determinant, which precludes its study by standard lattice QCD simulations. We therefore simulate lattice QCD at finite {mu} in the phase-quenched approximation, replacing the fermion determinant with its magnitude. (The phase-quenched approximation can be considered as simulating at finite isospin chemical potential 2{mu} for N{sub f}/2 u-type and N{sub F}/2 d-type quark flavors.) These simulations are used to study the finite-temperature transition for small {mu}, where there is some evidence that the position (and possibly the nature) of this transition is unchanged by this approximation. We look for the expected critical endpoint for 3-flavor QCD. Here, it has been argued that the critical point at zero {mu} would become the critical endpoint at small {mu}, for quark masses just above the critical mass. Our simulations indicate that this does not happen, and there is no such critical endpoint for small {mu}. We discuss how we might adapt techniques used for imaginary {mu} to improve the signal/noise ratio and strengthen our conclusions, using results from relatively low statistics studies.

  1. Lattice QCD at finite temperature and density in the phase-quenched approximation

    SciTech Connect

    Kogut, J. B.; Sinclair, D. K.

    2008-06-01

    QCD at a finite quark-number chemical potential {mu} has a complex fermion determinant, which precludes its study by standard lattice QCD simulations. We therefore simulate lattice QCD at finite {mu} in the phase-quenched approximation, replacing the fermion determinant with its magnitude. (The phase-quenched approximation can be considered as simulating at finite isospin chemical potential 2{mu} for N{sub f}/2 u-type and N{sub f}/2 d-type quark flavors.) These simulations are used to study the finite-temperature transition for small {mu}, where there is some evidence that the position (and possibly the nature) of this transition is unchanged by this approximation. We look for the expected critical endpoint for 3-flavor QCD. Here, it has been argued that the critical point at zero {mu} would become the critical endpoint at small {mu}, for quark masses just above the critical mass. Our simulations indicate that this does not happen, and there is no such critical endpoint for small {mu}. We discuss how we might adapt techniques used for imaginary {mu} to improve the signal/noise ratio and strengthen our conclusions, using results from relatively low statistics studies.

  2. Quark eigenmodes and lattice QCD

    NASA Astrophysics Data System (ADS)

    Liu, Guofeng

    In this thesis, we study a number of topics in lattice QCD through the low-lying quark eigenmodes in the domain wall fermion (DWF) formulation in the quenched approximation. Specifically, we present results for the chiral condensate measured from these eigenmodes; we investigate the QCD vacuum structure by looking at the correlation between the magnitude of the chirality density, |psi†(x)gamma5psi( x)|, and the normal density, psi†( x)psi(x), for these states; we study the behavior of DWF formulation at large quark masses by investigating the mass dependence of the eigenvalues of the physical four dimensional-states as well as the bulk, five-dimensional states.

  3. Hadronic Resonances from Lattice QCD

    SciTech Connect

    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.

  4. Hadronic Resonances from Lattice QCD

    SciTech Connect

    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.

  5. Nucleon Structure from Lattice QCD

    SciTech Connect

    David Richards

    2007-09-05

    Recent advances in lattice field theory, in computer technology and in chiral perturbation theory have enabled lattice QCD to emerge as a powerful quantitative tool in understanding hadron structure. I describe recent progress in the computation of the nucleon form factors and moments of parton distribution functions, before proceeding to describe lattice studies of the Generalized Parton Distributions (GPDs). In particular, I show how lattice studies of GPDs contribute to building a three-dimensional picture of the proton, I conclude by describing the prospects for studying the structure of resonances from lattice QCD.

  6. Two-color QCD at high density

    NASA Astrophysics Data System (ADS)

    Boz, Tamer; Giudice, Pietro; Hands, Simon; Skullerud, Jon-Ivar; Williams, Anthony G.

    2016-01-01

    QCD at high chemical potential has interesting properties such as deconfinement of quarks. Two-color QCD, which enables numerical simulations on the lattice, constitutes a laboratory to study QCD at high chemical potential. Among the interesting properties of two-color QCD at high density is the diquark condensation, for which we present recent results obtained on a finer lattice compared to previous studies. The quark propagator in two-color QCD at non-zero chemical potential is referred to as the Gor'kov propagator. We express the Gor'kov propagator in terms of form factors and present recent lattice simulation results.

  7. Lattice QCD and Nuclear Physics

    SciTech Connect

    Konstantinos Orginos

    2007-03-01

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

  8. Kenneth Wilson and Lattice QCD

    NASA Astrophysics Data System (ADS)

    Ukawa, Akira

    2015-09-01

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

  9. Lattice QCD clusters at Fermilab

    SciTech Connect

    Holmgren, D.; Mackenzie, Paul B.; Singh, Anitoj; Simone, Jim; /Fermilab

    2004-12-01

    As part of the DOE SciDAC ''National Infrastructure for Lattice Gauge Computing'' project, Fermilab builds and operates production clusters for lattice QCD simulations. This paper will describe these clusters. The design of lattice QCD clusters requires careful attention to balancing memory bandwidth, floating point throughput, and network performance. We will discuss our investigations of various commodity processors, including Pentium 4E, Xeon, Opteron, and PPC970. We will also discuss our early experiences with the emerging Infiniband and PCI Express architectures. Finally, we will present our predictions and plans for future clusters.

  10. Transverse momentum distributions inside the nucleon from lattice QCD

    SciTech Connect

    Musch, B. U.; Haegler, Ph.; Negele, J. W.; Schaefer, A.

    2011-07-15

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.

  11. RECENT LATTICE RESULTS ON FINITE TEMPERATURE AND DENSITY QCD, PART II.

    SciTech Connect

    KARSCH,F.

    2007-07-09

    We discuss recent progress in studies of QCD thermodynamics with almost physical light quark masses and a physical value of the strange quark mass. We summarize results on the transition temperature in QCD and analyze the relation between deconfinement and chiral symmetry restoration.

  12. Nuclear Physics and Lattice QCD

    SciTech Connect

    Beane, Silas

    2003-11-01

    Impressive progress is currently being made in computing properties and interac- tions of the low-lying hadrons using lattice QCD. However, cost limitations will, for the foreseeable future, necessitate the use of quark masses, Mq, that are signif- icantly larger than those of nature, lattice spacings, a, that are not significantly smaller than the physical scale of interest, and lattice sizes, L, that are not sig- nificantly larger than the physical scale of interest. Extrapolations in the quark masses, lattice spacing and lattice volume are therefore required. The hierarchy of mass scales is: L 1 j Mq j â ºC j a 1 . The appropriate EFT for incorporating the light quark masses, the finite lattice spacing and the lattice size into hadronic observables is C-PT, which provides systematic expansions in the small parame- ters e m L, 1/ Lâ ºC, p/â ºC, Mq/â ºC and aâ ºC . The lattice introduces other unphysical scales as well. Lattice QCD quarks will increasingly be artificially separated

  13. Berry Phase in Lattice QCD.

    PubMed

    Yamamoto, Arata

    2016-07-29

    We propose the lattice QCD calculation of the Berry phase, which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation. PMID:27517766

  14. Lattice gauge theory for QCD

    SciTech Connect

    DeGrand, T.

    1997-06-01

    These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and {alpha}{sub s} (M{sub z}), and B-{anti B} mixing. 67 refs., 36 figs.

  15. Lattice QCD in Background Fields

    SciTech Connect

    William Detmold, Brian Tiburzi, Andre Walker-Loud

    2009-06-01

    Electromagnetic properties of hadrons can be computed by lattice simulations of QCD in background fields. We demonstrate new techniques for the investigation of charged hadron properties in electric fields. Our current calculations employ large electric fields, motivating us to analyze chiral dynamics in strong QED backgrounds, and subsequently uncover surprising non-perturbative effects present at finite volume.

  16. Experimenting with Langevin lattice QCD

    SciTech Connect

    Gavai, R.V.; Potvin, J.; Sanielevici, S.

    1987-05-01

    We report on the status of our investigations of the effects of systematic errors upon the practical merits of Langevin updating in full lattice QCD. We formulate some rules for the safe use of this updating procedure and some observations on problems which may be common to all approximate fermion algorithms.

  17. Visualization Tools for Lattice QCD - Final Report

    SciTech Connect

    Massimo Di Pierro

    2012-03-15

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

  18. Form factors from lattice QCD

    SciTech Connect

    Dru Renner

    2012-04-01

    Precision computation of hadronic physics with lattice QCD is becoming feasible. The last decade has seen precent-level calculations of many simple properties of mesons, and the last few years have seen calculations of baryon masses, including the nucleon mass, accurate to a few percent. As computational power increases and algorithms advance, the precise calculation of a variety of more demanding hadronic properties will become realistic. With this in mind, I discuss the current lattice QCD calculations of generalized parton distributions with an emphasis on the prospects for well-controlled calculations for these observables as well. I will do this by way of several examples: the pion and nucleon form factors and moments of the nucleon parton and generalized-parton distributions.

  19. Innovations in Lattice QCD Algorithms

    SciTech Connect

    Konstantinos Orginos

    2006-06-25

    Lattice QCD calculations demand a substantial amount of computing power in order to achieve the high precision results needed to better understand the nature of strong interactions, assist experiment to discover new physics, and predict the behavior of a diverse set of physical systems ranging from the proton itself to astrophysical objects such as neutron stars. However, computer power alone is clearly not enough to tackle the calculations we need to be doing today. A steady stream of recent algorithmic developments has made an important impact on the kinds of calculations we can currently perform. In this talk I am reviewing these algorithms and their impact on the nature of lattice QCD calculations performed today.

  20. Nucleon Structure from Lattice QCD

    SciTech Connect

    Haegler, Philipp

    2011-10-24

    Hadron structure calculations in lattice QCD have seen substantial progress during recent years. We illustrate the achievements that have been made by discussing latest lattice results for a limited number of important observables related to nucleon form factors and generalized parton distributions. A particular focus is placed on the decomposition of the nucleon spin 1/2 in terms of quark spin and orbital angular momentum contributions. Results and limitations of the necessary chiral extrapolations based on ChPT will be briefly discussed.

  1. Nuclear Physics from Lattice QCD

    SciTech Connect

    William Detmold, Silas Beane, Konstantinos Orginos, Martin Savage

    2011-01-01

    We review recent progress toward establishing lattice Quantum Chromodynamics as a predictive calculational framework for nuclear physics. A survey of the current techniques that are used to extract low-energy hadronic scattering amplitudes and interactions is followed by a review of recent two-body and few-body calculations by the NPLQCD collaboration and others. An outline of the nuclear physics that is expected to be accomplished with Lattice QCD in the next decade, along with estimates of the required computational resources, is presented.

  2. Lattice QCD Beyond Ground States

    SciTech Connect

    Huey-Wen Lin; Saul D. Cohen

    2007-09-11

    In this work, we apply black box methods (methods not requiring input) to find excited-state energies. A variety of such methods for lattice QCD were introduced at the 3rd iteration of the numerical workshop series. We first review a selection of approaches that have been used in lattice calculations to determine multiple energy states: multiple correlator fits, the variational method and Bayesian fitting. In the second half, we will focus on a black box method, the multi-effective mass. We demonstrate the approach on a toy model, as well as on real lattice data, extracting multiple states from single correlators. Without complicated operator construction or specialized fitting programs, the black box method shows good consistency with the traditional approaches.

  3. LATTICE QCD THERMODYNAMICS WITH WILSON QUARKS.

    SciTech Connect

    EJIRI,S.

    2007-11-20

    We review studies of QCD thermodynamics by lattice QCD simulations with dynamical Wilson quarks. After explaining the basic properties of QCD with Wilson quarks at finite temperature including the phase structure and the scaling properties around the chiral phase transition, we discuss the critical temperature, the equation of state and heavy-quark free energies.

  4. Nuclear Force from Lattice QCD

    SciTech Connect

    Ishii, N.; Aoki, S.; Hatsuda, T.

    2007-07-13

    The nucleon-nucleon (NN) potential is studied by lattice QCD simulations in the quenched approximation, using the plaquette gauge action and the Wilson quark action on a 32{sup 4} [{approx_equal}(4.4 fm){sup 4}] lattice. A NN potential V{sub NN}(r) is defined from the equal-time Bethe-Salpeter amplitude with a local interpolating operator for the nucleon. By studying the NN interaction in the {sup 1}S{sub 0} and {sup 3}S{sub 1} channels, we show that the central part of V{sub NN}(r) has a strong repulsive core of a few hundred MeV at short distances (r < or approx. 0.5 fm) surrounded by an attractive well at medium and long distances. These features are consistent with the known phenomenological features of the nuclear force.

  5. Nuclear force from lattice QCD.

    PubMed

    Ishii, N; Aoki, S; Hatsuda, T

    2007-07-13

    The nucleon-nucleon (NN) potential is studied by lattice QCD simulations in the quenched approximation, using the plaquette gauge action and the Wilson quark action on a 32(4) [approximately (4.4 fm)(4)] lattice. A NN potential V(NN)(r) is defined from the equal-time Bethe-Salpeter amplitude with a local interpolating operator for the nucleon. By studying the NN interaction in the (1)S(0) and (3)S(1) channels, we show that the central part of V(NN)(r) has a strong repulsive core of a few hundred MeV at short distances (r approximately < 0.5 fm) surrounded by an attractive well at medium and long distances. These features are consistent with the known phenomenological features of the nuclear force. PMID:17678213

  6. Gluonic transversity from lattice QCD

    NASA Astrophysics Data System (ADS)

    Detmold, W.; Shanahan, P. E.

    2016-07-01

    We present an exploratory study of the gluonic structure of the ϕ meson using lattice QCD (LQCD). This includes the first investigation of gluonic transversity via the leading moment of the twist-2 double-helicity-flip gluonic structure function Δ (x ,Q2). This structure function only exists for targets of spin J ≥1 and does not mix with quark distributions at leading twist, thereby providing a particularly clean probe of gluonic degrees of freedom. We also explore the gluonic analogue of the Soffer bound which relates the helicity flip and nonflip gluonic distributions, finding it to be saturated at the level of 80%. This work sets the stage for more complex LQCD studies of gluonic structure in the nucleon and in light nuclei where Δ (x ,Q2) is an "exotic glue" observable probing gluons in a nucleus not associated with individual nucleons.

  7. QCD Factorization and PDFs from Lattice QCD Calculation

    NASA Astrophysics Data System (ADS)

    Ma, Yan-Qing; Qiu, Jian-Wei

    2015-02-01

    In this talk, we review a QCD factorization based approach to extract parton distribution and correlation functions from lattice QCD calculation of single hadron matrix elements of quark-gluon operators. We argue that although the lattice QCD calculations are done in the Euclidean space, the nonperturbative collinear behavior of the matrix elements are the same as that in the Minkowski space, and could be systematically factorized into parton distribution functions with infrared safe matching coefficients. The matching coefficients can be calculated perturbatively by applying the factorization formalism on to asymptotic partonic states.

  8. The CKM Matrix from Lattice QCD

    SciTech Connect

    Mackenzie, Paul B.; /Fermilab

    2009-07-01

    Lattice QCD plays an essential role in testing and determining the parameters of the CKM theory of flavor mixing and CP violation. Very high precisions are required for lattice calculations analyzing CKM data; I discuss the prospects for achieving them. Lattice calculations will also play a role in investigating flavor mixing and CP violation beyond the Standard Model.

  9. Parton distributions from lattice QCD: an update

    SciTech Connect

    Detmold, W; Melnitchouk, W; Thomas, A W

    2004-04-01

    We review the extraction of parton distributions from their moments calculated in lattice QCD, focusing in particular on their extrapolation to the physical region. As examples, we consider both the unpolarized and polarized isovector parton distributions of the nucleon.

  10. Strange Baryon Physics in Full Lattice QCD

    SciTech Connect

    Huey-Wen Lin

    2007-11-01

    Strange baryon spectra and form factors are key probes to study excited nuclear matter. The use of lattice QCD allows us to test the strength of the Standard Model by calculating strange baryon quantities from first principles.

  11. Lattice and Phase Diagram in QCD

    SciTech Connect

    Lombardo, Maria Paola

    2008-10-13

    Model calculations have produced a number of very interesting expectations for the QCD Phase Diagram, and the task of a lattice calculations is to put these studies on a quantitative grounds. I will give an overview of the current status of the lattice analysis of the QCD phase diagram, from the quantitative results of mature calculations at zero and small baryochemical potential, to the exploratory studies of the colder, denser phase.

  12. Lattice QCD and the Jefferson Laboratory Program

    SciTech Connect

    Jozef Dudek, Robert Edwards, David Richards, Konstantinos Orginos

    2011-06-01

    Lattice gauge theory provides our only means of performing \\textit{ab initio} calculations in the non-perturbative regime. It has thus become an increasing important component of the Jefferson Laboratory physics program. In this paper, we describe the contributions of lattice QCD to our understanding of hadronic and nuclear physics, focusing on the structure of hadrons, the calculation of the spectrum and properties of resonances, and finally on deriving an understanding of the QCD origin of nuclear forces.

  13. Lattice QCD input for axion cosmology

    NASA Astrophysics Data System (ADS)

    Berkowitz, Evan; Buchoff, Michael I.; Rinaldi, Enrico

    2015-08-01

    One intriguing beyond-the-Standard-Model particle is the QCD axion, which could simultaneously provide a solution to the Strong C P Problem and account for some, if not all, of the dark matter density in the Universe. This particle is a pseudo-Nambu-Goldstone boson of the conjectured Peccei-Quinn symmetry of the Standard Model. Its mass and interactions are suppressed by a heavy symmetry-breaking scale, fa, the value of which is roughly greater than 109 GeV (or, conversely, the axion mass, ma, is roughly less than 104 μ eV ). The density of axions in the Universe, which cannot exceed the relic dark matter density and is a quantity of great interest in axion experiments like ADMX, is a result of the early Universe interplay between cosmological evolution and the axion mass as a function of temperature. The latter quantity is proportional to the second derivative of the temperature-dependent QCD free energy with respect to the C P -violating phase, θ . However, this quantity is generically nonperturbative, and previous calculations have only employed instanton models at the high temperatures of interest (roughly 1 GeV). In this and future works, we aim to calculate the temperature-dependent axion mass at small θ from first-principle lattice calculations, with controlled statistical and systematic errors. Once calculated, this temperature-dependent axion mass is input for the classical evolution equations of the axion density of the Universe, which is required to be less than or equal to the dark matter density. Due to a variety of lattice systematic effects at the very high temperatures required, we perform a calculation of the leading small-θ cumulant of the theta vacua on large volume lattices for SU(3) Yang-Mills with high statistics as a first proof of concept, before attempting a full QCD calculation in the future. From these pure glue results, the misalignment mechanism yields the axion mass bound ma≥(14.6 ±0.1 ) μ eV when Peccei-Quinn breaking occurs

  14. Excited light isoscalar mesons from lattice QCD

    SciTech Connect

    Christopher Thomas

    2011-07-01

    I report a recent lattice QCD calculation of an excited spectrum of light isoscalar mesons, something that has up to now proved challenging for lattice QCD. With novel techniques we extract an extensive spectrum with high statistical precision, including spin-four states and, for the first time, light isoscalars with exotic quantum numbers. In addition, the hidden flavour content of these mesons is determined, providing a window on annihilation dynamics in QCD. I comment on future prospects including applications to the study of resonances.

  15. Calculation of the nucleon axial charge in lattice QCD

    SciTech Connect

    D. B. Renner; R. G. Edwards; G. Fleming; Ph. Hagler; J. W. Negele; K. Orginos; A. V. Pochinsky; D. G. Richards; W. Schroers

    2006-09-01

    Protons and neutrons have a rich structure in terms of their constituents, the quarks and gluons. Understanding this structure requires solving Quantum Chromodynamics (QCD). However QCD is extremely complicated, so we must numerically solve the equations of QCD using a method known as lattice QCD. Here we describe a typical lattice QCD calculation by examining our recent computation of the nucleon axial charge.

  16. Excited light meson spectroscopy from lattice QCD

    SciTech Connect

    Christopher Thomas, Hadron Spectrum Collaboration

    2012-04-01

    I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.

  17. The Chroma Software System for Lattice QCD

    SciTech Connect

    Robert Edwards; Balint Joo

    2004-06-01

    We describe aspects of the Chroma software system for lattice QCD calculations. Chroma is an open source C++ based software system developed using the software infrastructure of the US SciDAC initiative. Chroma interfaces with output from the BAGEL assembly generator for optimized lattice fermion kernels on some architectures. It can be run on workstations, clusters and the QCDOC supercomputer.

  18. Precision lattice QCD: challenges and prospects

    NASA Astrophysics Data System (ADS)

    Hashimoto, Shoji

    2013-04-01

    With Peta-flops scale computational resources, lattice QCD simulation has recently reached one of its primary goals, i.e. reproducing the low-lying hadron spectrum starting from the QCD Lagrangian. Applications to various other phenomenological quantities, for which no other way of precise theoretical calculation is available, would become the next milestone. In this talk I will provide a brief overview of the field and summarize the remaining problems to be solved before achieving the precision calculations.

  19. Exploring hyperons and hypernuclei with lattice QCD

    SciTech Connect

    Beane, S.R.; Bedaque, P.F.; Parreno, A.; Savage, M.J.

    2003-01-01

    In this work we outline a program for lattice QCD that wouldprovide a first step toward understanding the strong and weakinteractions of strange baryons. The study of hypernuclear physics hasprovided a significant amount of information regarding the structure andweak decays of light nuclei containing one or two Lambda's, and Sigma's.From a theoretical standpoint, little is known about the hyperon-nucleoninteraction, which is required input for systematic calculations ofhypernuclear structure. Furthermore, the long-standing discrepancies inthe P-wave amplitudes for nonleptonic hyperon decays remain to beunderstood, and their resolution is central to a better understanding ofthe weak decays of hypernuclei. We present a framework that utilizesLuscher's finite-volume techniques in lattice QCD to extract thescattering length and effective range for Lambda-N scattering in both QCDand partially-quenched QCD. The effective theory describing thenonleptonic decays of hyperons using isospin symmetry alone, appropriatefor lattice calculations, is constructed.

  20. Transverse momentum distributions inside the nucleon from Lattice QCD

    SciTech Connect

    Bernhard Musch, Philipp Hagler, John Negele, Andreas Schafer

    2010-06-01

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

  1. String breaking in four dimensional lattice QCD

    SciTech Connect

    Duncan, A.; Eichten, E.; Thacker, H.

    2001-06-01

    Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on a 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse [but O(a{sup 2}) improved] lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R{approx}>1 fm.

  2. Generalized Parton Distributions from Lattice QCD

    SciTech Connect

    Orginos, Konstantinos

    2007-10-01

    I review recent results on moments of Generalized Parton Distribution functions (GPDs) from Lattice QCD. In particular, I discuss the methodology of lattice calculations, and how various systematic errors arising in these calculations are controlled. I conclude with an overview of the roadmap towards precision non-perturbative determination of moments of GPDs, and discuss the potential impact to the extraction of GPDs form experiment.

  3. Large Scale Commodity Clusters for Lattice QCD

    SciTech Connect

    A. Pochinsky; W. Akers; R. Brower; J. Chen; P. Dreher; R. Edwards; S. Gottlieb; D. Holmgren; P. Mackenzie; J. Negele; D. Richards; J. Simone; W. Watson

    2002-06-01

    We describe the construction of large scale clusters for lattice QCD computing being developed under the umbrella of the U.S. DoE SciDAC initiative. We discuss the study of floating point and network performance that drove the design of the cluster, and present our plans for future multi-Terascale facilities.

  4. Toward lattice QCD simulation on AP1000

    NASA Astrophysics Data System (ADS)

    Ohta, Shigemi

    AP1000 is Fujitsu Laboratory's experimental parallel computer consisting of up to 1024 microcomputers called cells. It is found that each AP1000 cell can sustain two to three megaflops computational speed for full QCD lattice numerical simulations in IEEE 64-bit floating point format

  5. Marking up lattice QCD configurations and ensembles

    SciTech Connect

    P.Coddington; B.Joo; C.M.Maynard; D.Pleiter; T.Yoshie

    2007-10-01

    QCDml is an XML-based markup language designed for sharing QCD configurations and ensembles world-wide via the International Lattice Data Grid (ILDG). Based on the latest release, we present key ingredients of the QCDml in order to provide some starting points for colleagues in this community to markup valuable configurations and submit them to the ILDG.

  6. Heavy quark masses from lattice QCD

    NASA Astrophysics Data System (ADS)

    Lytle, Andrew T.

    2016-07-01

    Progress in quark mass determinations from lattice QCD is reviewed, focusing on results for charm and bottom mass. These are of particular interest for precision Higgs studies. Recent determinations have achieved percent-level uncertainties with controlled systematics. Future prospects for these calculations are also discussed.

  7. Full CKM matrix with lattice QCD

    SciTech Connect

    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.

  8. Exploring Three Nucleon Forces in Lattice QCD

    SciTech Connect

    Doi, Takumi

    2011-10-21

    We study the three nucleon force in N{sub f} = 2 dynamical clover fermion lattice QCD, utilizing the Nambu-Bethe-Salpeter wave function of the three nucleon system. Since parity-odd two nucleon potentials are not available in lattice QCD at this moment, we develop a new formulation to extract the genuine three nucleon force which requires only the information of parity-even two nucleon potentials. In order to handle the extremely expensive calculation cost, we consider a specific three-dimensional coordinate configuration for the three nucleons. We find that the linear setup is advantageous, where nucleons are aligned linearly with equal spacings. The lattice calculation is performed with 16{sup 3}x32 configurations at {beta} = 1.95, m{sub {pi}} = 1.13 GeV generated by CP-PACS Collaboration, and the result of the three nucleon force in triton channel is presented.

  9. Nucleon Structure from Dynamical Lattice QCD

    SciTech Connect

    Huey-Wen Lin

    2007-06-01

    We present lattice QCD numerical calculations of hadronic structure functions and form factors from full-QCD lattices, with a chirally symmetric fermion action, domain-wall fermions, for the sea and valence quarks. The lattice spacing is about 0.12 fm with physical volume approximately (2 fm)3 for RBC 2-flavor ensembles and (3 fm)3 for RBC/UKQCD 2+1-flavor dynamical ones. The lightest sea quark mass is about 1/2 the strange quark mass for the former ensembles and 1/4 for the latter ones. Our calculations include: isovector vector- and axial-charge form factors and the first few moments of the polarized and unpolarized structure functions of the nucleon. Nonperturbative renormalization in RI/MOM scheme is applied.

  10. Nucleon Structure from Dynamical Lattice QCD

    SciTech Connect

    Lin, H.-W.

    2007-06-13

    We present lattice QCD numerical calculations of hadronic structure functions and form factors from full-QCD lattices, with a chirally symmetric fermion action, domain-wall fermions, for the sea and valence quarks. The lattice spacing is about 0.12 fm with physical volume approximately (2 fm)3 for RBC 2-flavor ensembles and (3 fm)3 for RBC/UKQCD 2+1-flavor dynamical ones. The lightest sea quark mass is about 1/2 the strange quark mass for the former ensembles and 1/4 for the latter ones. Our calculations include: isovector vector- and axial-charge form factors and the first few moments of the polarized and unpolarized structure functions of the nucleon. Nonperturbative renormalization in RI/MOM scheme is applied.

  11. Heavy quarks and lattice QCD

    SciTech Connect

    Andreas S. Kronfeld

    2003-11-05

    This paper is a review of heavy quarks in lattice gauge theory, focusing on methodology. It includes a status report on some of the calculations that are relevant to heavy-quark spectroscopy and to flavor physics.

  12. PC Clusters for Lattice QCD

    NASA Astrophysics Data System (ADS)

    Holmgren, D. J.

    2005-03-01

    In the last several years, tightly coupled PC clusters have become widely applied, cost effective resources for lattice gauge computations. This paper discusses the practice of building such clusters, in particular balanced design requirements. I review and quantify the improvements over time of key performance parameters and overall price to performance ratio. Applying these trends and technology forecasts given by computer equipment manufacturers, I predict the range of price to performance for lattice codes expected in the next several years.

  13. Exploring Hyperons and Hypernuclei with Lattice QCD

    SciTech Connect

    S.R. Beane; P.F. Bedaque; A. Parreno; M.J. Savage

    2005-01-01

    In this work we outline a program for lattice QCD that would provide a first step toward understanding the strong and weak interactions of strange baryons. The study of hypernuclear physics has provided a significant amount of information regarding the structure and weak decays of light nuclei containing one or two Lambda's, and Sigma's. From a theoretical standpoint, little is known about the hyperon-nucleon interaction, which is required input for systematic calculations of hypernuclear structure. Furthermore, the long-standing discrepancies in the P-wave amplitudes for nonleptonic hyperon decays remain to be understood, and their resolution is central to a better understanding of the weak decays of hypernuclei. We present a framework that utilizes Luscher's finite-volume techniques in lattice QCD to extract the scattering length and effective range for Lambda-N scattering in both QCD and partially-quenched QCD. The effective theory describing the nonleptonic decays of hyperons using isospin symmetry alone, appropriate for lattice calculations, is constructed.

  14. Axion cosmology, lattice QCD and the dilute instanton gas

    NASA Astrophysics Data System (ADS)

    Borsanyi, Sz.; Dierigl, M.; Fodor, Z.; Katz, S. D.; Mages, S. W.; Nogradi, D.; Redondo, J.; Ringwald, A.; Szabo, K. K.

    2016-01-01

    Axions are one of the most attractive dark matter candidates. The evolution of their number density in the early universe can be determined by calculating the topological susceptibility χ (T) of QCD as a function of the temperature. Lattice QCD provides an ab initio technique to carry out such a calculation. A full result needs two ingredients: physical quark masses and a controlled continuum extrapolation from non-vanishing to zero lattice spacings. We determine χ (T) in the quenched framework (infinitely large quark masses) and extrapolate its values to the continuum limit. The results are compared with the prediction of the dilute instanton gas approximation (DIGA). A nice agreement is found for the temperature dependence, whereas the overall normalization of the DIGA result still differs from the non-perturbative continuum extrapolated lattice results by a factor of order ten. We discuss the consequences of our findings for the prediction of the amount of axion dark matter.

  15. Hadronic Interactions from Lattice QCD

    SciTech Connect

    Konstantinos Orginos

    2006-03-19

    In this talk I discuss a few recent results on lattice calculations of scattering lengths in hadronic processes. In particular, I present the scattering length of the pion-pion scattering in the I=2 channel and the nucleon-nucleon {sup 1}S{sub 0} channel and {sup 3}S{sub 1}-{sup 3}D{sub 1} coupled channels.

  16. Connecting physical resonant amplitudes and lattice QCD

    NASA Astrophysics Data System (ADS)

    Bolton, Daniel R.; Briceño, Raúl A.; Wilson, David J.

    2016-06-01

    We present a determination of the isovector, P-wave ππ scattering phase shift obtained by extrapolating recent lattice QCD results from the Hadron Spectrum Collaboration using mπ = 236 MeV. The finite volume spectra are described using extensions of Lüscher's method to determine the infinite volume Unitarized Chiral Perturbation Theory scattering amplitude. We exploit the pion mass dependence of this effective theory to obtain the scattering amplitude at mπ = 140 MeV. The scattering phase shift is found to agree with experiment up to center of mass energies of 1.2 GeV. The analytic continuation of the scattering amplitude to the complex plane yields a ρ-resonance pole at Eρ = [ 755 (2) (1) (20 -i/2 129 (3) (1) 7 1) ] MeV. The techniques presented illustrate a possible pathway towards connecting lattice QCD observables of few-body, strongly interacting systems to experimentally accessible quantities.

  17. Exploring Flavor Physics with Lattice QCD

    NASA Astrophysics Data System (ADS)

    Du, Daping; Fermilab/MILC Collaborations Collaboration

    2016-03-01

    The Standard Model has been a very good description of the subatomic particle physics. In the search for physics beyond the Standard Model in the context of flavor physics, it is important to sharpen our probes using some gold-plated processes (such as B rare decays), which requires the knowledge of the input parameters, such as the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and other nonperturbative quantities, with sufficient precision. Lattice QCD is so far the only first-principle method which could compute these quantities with competitive and systematically improvable precision using the state of the art simulation techniques. I will discuss the recent progress of lattice QCD calculations on some of these nonpurturbative quantities and their applications in flavor physics. I will also discuss the implications and future perspectives of these calculations in flavor physics.

  18. Connecting physical resonant amplitudes and lattice QCD

    NASA Astrophysics Data System (ADS)

    Bolton, Daniel R.; Briceño, Raúl A.; Wilson, David J.

    2016-06-01

    We present a determination of the isovector, P-wave ππ scattering phase shift obtained by extrapolating recent lattice QCD results from the Hadron Spectrum Collaboration using mπ = 236 MeV. The finite volume spectra are described using extensions of Lüscher's method to determine the infinite volume Unitarized Chiral Perturbation Theory scattering amplitude. We exploit the pion mass dependence of this effective theory to obtain the scattering amplitude at mπ = 140 MeV. The scattering phase shift is found to agree with experiment up to center of mass energies of 1.2 GeV. The analytic continuation of the scattering amplitude to the complex plane yields a ρ-resonance pole at Eρ = [ 755 (2) (1) (20 02) -i/2 129 (3) (1) (7 1) ] MeV. The techniques presented illustrate a possible pathway towards connecting lattice QCD observables of few-body, strongly interacting systems to experimentally accessible quantities.

  19. Ab initio Hadron structure from lattice QCD

    SciTech Connect

    J.D. Bratt; R.G. Edwards; M. Engelhardt; G.T. Fleming; Ph. Hägler; B. Musch; J.W. Negele; K. Orginos; A.V. Pochinsky; D.B. Renner; D.G. Richards; W. Schroers

    2007-06-01

    Early scattering experiments revealed that the proton was not a point particle but a bound state of many quarks and gluons. Deep inelastic scattering (DIS) experiments have accurately determined the probability of struck quarks carrying a fraction of the proton's momentum. The current generation of experiments and Lattice QCD calculations will provide detailed multi-dimensional pictures of the distributions of quarks and gluons inside the proton.

  20. BB Potentials in Quenched Lattice QCD

    SciTech Connect

    William Detmold; Kostas Orginos; Martin J. Savage

    2007-12-01

    The potentials between two B-mesons are computed in the heavy-quark limit using quenched lattice QCD at $m_\\pi\\sim 400~{\\rm MeV}$. Non-zero central potentials are clearly evident in all four spin-isospin channels, (I,s_l) = (0,0) , (0,1) , (1,0) , (1,1), where s_l is the total spin of the light degrees of freedom. At short distance, we find repulsion in the $I\

  1. Radiative Charmonium Physics from Lattice QCD

    SciTech Connect

    Jozef Dudek; Robert Edwards; David Richards; Nilmani Mathur

    2007-08-09

    Charmonium is an attractive system for the application of lattice QCD methods owing to the possibility of computing with the physical quark mass in a reasonable time. While the sub-threshold spectrum has been considered in some detail in previous works, it is only very recently that further properties such as radiative transitions and two-photon decays have come to be calculated; herein we discuss this recent progress.

  2. Bottomonium above Deconfinement in Lattice Nonrelativistic QCD

    SciTech Connect

    Aarts, G.; Kim, S.; Lombardo, M. P.; Oktay, M. B.; Ryan, S. M.; Sinclair, D. K.; Skullerud, J.-I.

    2011-02-11

    We study the temperature dependence of bottomonium for temperatures in the range 0.4T{sub c}lattice QCD simulations for N{sub f}=2 light flavors on a highly anisotropic lattice. We find that the {Upsilon} is insensitive to the temperature in this range, while the {chi}{sub b} propagators show a crossover from the exponential decay characterizing the hadronic phase to a power-law behavior consistent with nearly free dynamics at T{approx_equal}2T{sub c}.

  3. Strangeness of the nucleon from lattice QCD

    NASA Astrophysics Data System (ADS)

    Alexandrou, Constantia; Constantinou, Martha; Dinter, Simon; Drach, Vincent; Hadjiyiannakou, Kyriakos; Jansen, Karl; Koutsou, Giannis; Vaquero, Alejandro; ETM Collaboration

    2015-05-01

    We present a nonperturbative calculation of the strangeness of the nucleon yN within the framework of lattice QCD. This observable is known to be an important cornerstone to interpret results from direct dark matter detection experiments. We perform a lattice computation for yN with an analysis of systematic effects originating from discretization, finite size, chiral extrapolation and excited state effects leading to the value of yN=0.173 (50 ) . The rather large uncertainty of this value of yN is dominated by systematic uncertainties which we are able to quantify in this work.

  4. FermiQCD: A tool kit for parallel lattice QCD applications

    SciTech Connect

    Di Pierro, M.

    2002-03-01

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

  5. Perfect Actions and Operators for Lattice QCD

    NASA Astrophysics Data System (ADS)

    Wiese, Uwe-Jens

    1996-05-01

    Wilson's renormalization group implies that lattice actions located on a renormalized trajectory emanating from a fixed point represent perfect discretizations of continuum physics. With a perfect action the spectrum of a lattice theory is identical with the one of the continuum theory even at finite lattice spacing. Similarly, perfect operators yield cut-off independent matrix elements. Hence, continuum QCD can in principle be reconstructed from a lattice with finite spacing. In practice it is difficult to construct perfect actions and perfect operators explicitly. Here perturbation theory is used to derive perfect actions for quarks and gluons by performing a block renormalization group transformation directly from the continuum. The renormalized trajectory for free massive quarks is identified and a parameter in the renormalization group transformation is tuned such that for 1-d configurations the perfect action reduces to the nearest neighbor Wilson fermion action. Then the 4-d perfect action turns out to be extremely local as well, which is vital for numerical simulations. The fixed point action for free gluons is also obtained by blocking from the continuum. For 2-d configurations it reduces to the standard plaquette action, and for 4-d configurations it is still very local. With interactions between quarks and gluons switched on the perfect quark-gluon and 3-gluon vertex functions are computed analytically. In particular, a perfect clover term can be extracted from the quark-gluon vertex. The perturbatively perfect action is directly applicable to heavy quark physics. The construction of a perfect QCD action for light quarks should include nonperturbative effects, which is possible using numerical methods. Classically perfect quark and gluon fields are constructed as well. They allow to interpolate the continuum fields from the lattice data. In this way one can obtain information about space-time regions between lattice points. The classically perfect fields

  6. Radiative Transitions in Charmonium from Lattice QCD

    SciTech Connect

    Jozef Dudek; Robert Edwards; David Richards

    2006-01-17

    Radiative transitions between charmonium states offer an insight into the internal structure of heavy-quark bound states within QCD. We compute, for the first time within lattice QCD, the transition form-factors of various multipolarities between the lightest few charmonium states. In addition, we compute the experimentally unobservable, but physically interesting vector form-factors of the {eta}{sub c}, J/{psi} and {chi}{sub c0}. To this end we apply an ambitious combination of lattice techniques, computing three-point functions with heavy domain wall fermions on an anisotropic lattice within the quenched approximation. With an anisotropy {xi} = 3 at a{sub s} {approx} 0.1 fm we find a reasonable gross spectrum and a hyperfine splitting {approx}90 MeV, which compares favorably with other improved actions. In general, after extrapolation of lattice data at non-zero Q{sup 2} to the photopoint, our results agree within errors with all well measured experimental values. Furthermore, results are compared with the expectations of simple quark models where we find that many features are in agreement; beyond this we propose the possibility of constraining such models using our extracted values of physically unobservable quantities such as the J/{psi} quadrupole moment. We conclude that our methods are successful and propose to apply them to the problem of radiative transitions involving hybrid mesons, with the eventual goal of predicting hybrid meson photoproduction rates at the GlueX experiment.

  7. Lattice QCD simulations of the Zc+ channel

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    We discuss the lattice QCD simulations that search for the Zc+ with the unconventional quark content c ¯c d ¯u in the channel IG(JPC) = 1+(1+-). The major challenge is due to the two-meson states J /Ψ π , Ψ2 Sπ , Ψ1 Dπ , D D¯*, D *D¯*, ηcρ that are also inevitably present in this channel. The available lattice simulations find expected two-meson eigenstates, but no additional eigenstate as a candidate for Zc+ . This is in a striking contrast to the lattice results in the flavour non-exotic channels, where additional states are found in relation to most of the known resonances and bound states.

  8. Spectroscopy of charmed baryons from lattice QCD

    SciTech Connect

    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.

  9. Electromagnetic polarizabilities: Lattice QCD in background fields

    SciTech Connect

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

    2012-04-01

    Chiral perturbation theory makes definitive predictions for the extrinsic behavior of hadrons in external electric and magnetic fields. Near the chiral limit, the electric and magnetic polarizabilities of pions, kaons, and nucleons are determined in terms of a few well-known parameters. In this limit, hadrons become quantum mechanically diffuse as polarizabilities scale with the inverse square-root of the quark mass. In some cases, however, such predictions from chiral perturbation theory have not compared well with experimental data. Ultimately we must turn to first principles numerical simulations of QCD to determine properties of hadrons, and confront the predictions of chiral perturbation theory. To address the electromagnetic polarizabilities, we utilize the background field technique. Restricting our attention to calculations in background electric fields, we demonstrate new techniques to determine electric polarizabilities and baryon magnetic moments for both charged and neutral states. As we can study the quark mass dependence of observables with lattice QCD, the lattice will provide a crucial test of our understanding of low-energy QCD, which will be timely in light of ongoing experiments, such as at COMPASS and HI gamma S.

  10. Charmed bottom baryon spectroscopy from lattice QCD

    DOE PAGESBeta

    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

  11. Charmed bottom baryon spectroscopy from lattice QCD

    SciTech Connect

    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 physical pion mass using SU(4|2) heavy-hadron chiral perturbation theory including 1/mQ and finite-volume effects. For the 14 singly heavy baryons that have already been observed, our results agree with the experimental values within the uncertainties. We compare our predictions for the hitherto unobserved states with other lattice calculations and quark-model studies.

  12. Extracting Electric Polarizabilities from Lattice QCD

    SciTech Connect

    Will Detmold, William Detmold, Brian Tiburzi, Andre Walker-Loud

    2009-05-01

    Charged and neutral, pion and kaon electric polarizabilities are extracted from lattice QCD using an ensemble of anisotropic gauge configurations with dynamical clover fermions. We utilize classical background fields to access the polarizabilities from two-point correlation functions. Uniform background fields are achieved by quantizing the electric field strength with the proper treatment of boundary flux. These external fields, however, are implemented only in the valence quark sector. A novel method to extract charge particle polarizabilities is successfully demonstrated for the first time.

  13. Nuclear correlation functions in lattice QCD

    SciTech Connect

    Detmold, William; Orginos, Konstantinos

    2013-06-01

    We consider the problem of calculating the large number of Wick contractions necessary to compute states with the quantum numbers of many baryons in lattice QCD. We consider a constructive approach and a determinant-based approach and show that these methods allow the required contractions to be performed for certain choices of interpolating operators. Examples of correlation functions computed using these techniques are shown for the quantum numbers of the light nuclei, $^4$He, $^8$Be, $^{12}$C, $^{16}$O and $^{28}$Si.

  14. Multi-hadron systems in lattice QCD

    SciTech Connect

    Will Detmold

    2009-07-01

    Lattice QCD is currently entering the stage when it can usefully be applied to systems of multiple hadrons. I briefly review the status of recent calculations of scattering parameters in the two hadron sector and discuss recent calculations of systems composed of many mesons or baryons. In the mesonic case, the NPLQCD collaboration has continued its study of systems of up to twelve pions or kaons and have computed the effect of such a hadronic medium on the static quark potential. High statistics calculations on anisotropic lattices have allowed for precision extraction of the energies and scattering phase shifts of various two baryon systems and, for the first time, the energies of certain three baryon systems have been computed.

  15. Wilson Dslash Kernel From Lattice QCD Optimization

    SciTech Connect

    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.

  16. Lattice QCD production on commodity clusters at Fermilab

    SciTech Connect

    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.

  17. Method to study complex systems of mesons in lattice QCD

    DOE PAGESBeta

    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

  18. Exploring quark transverse momentum distributions with lattice QCD

    SciTech Connect

    Bernhard U. Musch, Philipp Hagler, John W. Negele, Andreas Schafer

    2011-05-01

    We discuss in detail a method to study transverse momentum dependent parton distribution functions (TMDs) using lattice QCD. To develop the formalism and to obtain first numerical results, we directly implement a bi-local quark-quark operator connected by a straight Wilson line, allowing us to study T-even, "process-independent" TMDs. Beyond results for x-integrated TMDs and quark densities, we present a study of correlations in x and transverse momentum. Our calculations are based on domain wall valence quark propagators by the LHP collaboration calculated on top of gauge configurations provided by MILC with 2+1 flavors of asqtad-improved staggered sea quarks.

  19. Searching for X (3872) using lattice QCD

    NASA Astrophysics Data System (ADS)

    Lee, Song-Haeng; Detar, Carleton; MILC / Fermilab Collaboration

    2016-03-01

    For decades, many excited charmonium states have been discovered that cannot be explained within the conventional quark model. Among the those mesons, the narrow charmonium-like state X (3872) has been examined using various phenomenological models, however, the question for its constituent still remains open. One of the strong candidates is a DD* molecular state because its mass is within 1MeV of the DD* threshold, however, such a molecular state can't be directly studied by perturbative QCD in such a low energy regime where the interaction of the colored quarks and gluons is very strong. Numerical simulation with lattice QCD provides a nonperturbative, ab initio method for studying this mysterious meson state. In this talk, I present preliminary simulation results for this charmonium-like states with quantum numbers JPC =1++ in both the isospin 0 and 1 channels. We use interpolating operators including both the conventional excited P-wave charmonium state (χc 1) and the DD* open charm state for the isospin 0 channel, but only DD* for the isospin 1 channel. We extract large negative S-wave scattering length and find an X (3872) candidate 13 +/- 6 MeV below the DD* threshold in the isospin 0 channel.

  20. Thermodynamics of Strong-Interaction Matter from Lattice QCD

    NASA Astrophysics Data System (ADS)

    Ding, Heng-Tong; Karsch, Frithjof; Mukherjee, Swagato

    We review results from lattice QCD calculations on the thermodynamics of strong-interaction matter with emphasis on input these calculations can provide to the exploration of the phase diagram and properties of hot and dense matter created in heavy ion experiments. This review is organized in sections as follows: (1) Introduction, (2) QCD thermodynamics on the lattice, (3) QCD phase diagram at high temperature, (4) Bulk thermodynamics, (5) Fluctuations of conserved charges, (6) Transport properties, (7) Open heavy flavors and heavy quarkonia, (8) QCD in external magnetic fields, (9) Summary.

  1. Status of Average-x from Lattice QCD

    SciTech Connect

    Dru Renner

    2011-09-01

    As algorithms and computing power have advanced, lattice QCD has become a precision technique for many QCD observables. However, the calculation of nucleon matrix elements remains an open challenge. I summarize the status of the lattice effort by examining one observable that has come to represent this challenge, average-x: the fraction of the nucleon's momentum carried by its quark constituents. Recent results confirm a long standing tendency to overshoot the experimentally measured value. Understanding this puzzle is essential to not only the lattice calculation of nucleon properties but also the broader effort to determine hadron structure from QCD.

  2. Introductory lectures on lattice QCD at nonzero baryon number

    NASA Astrophysics Data System (ADS)

    Aarts, Gert

    2016-04-01

    These lecture notes contain an elementary introduction to lattice QCD at nonzero chemical potential. Topics discussed include chemical potential in the continuum and on the lattice; the sign, overlap and Silver Blaze problems; the phase boundary at small chemical potential; imaginary chemical potential; and complex Langevin dynamics. An incomplete overview of other approaches is presented as well. These lectures are meant for postgraduate students and postdocs with an interest in extreme QCD. A basic knowledge of lattice QCD is assumed but not essential. Some exercises are included at the end.

  3. Two-flavor lattice QCD with a finite density of heavy quarks: heavy-dense limit and "particle-hole" symmetry

    NASA Astrophysics Data System (ADS)

    Rindlisbacher, Tobias; de Forcrand, Philippe

    2016-02-01

    We investigate the properties of the half-filling point in lattice QCD (LQCD), in particular the disappearance of the sign problem and the emergence of an apparent particle-hole symmetry, and try to understand where these properties come from by studying the heavy-dense fermion determinant and the corresponding strong-coupling partition function (which can be integrated analytically). We then add in a first step an effective Polyakov loop gauge action (which reproduces the leading terms in the character expansion of the Wilson gauge action) to the heavy-dense partition function and try to analyze how some of the properties of the half-filling point change when leaving the strong coupling limit. In a second step, we take also the leading nearest-neighbor fermion hopping terms into account (including gauge interactions in the fundamental representation) and mention how the method could be improved further to incorporate the full set of nearest-neighbor fermion hoppings. Using our mean-field method, we also obtain an approximate ( μ, T) phase diagram for heavy-dense LQCD at finite inverse gauge coupling β. Finally, we propose a simple criterion to identify the chemical potential beyond which lattice artifacts become dominant.

  4. Recent progress in lattice QCD at finite temperature

    SciTech Connect

    Petreczky,P.

    2009-02-01

    I review recent progress in finite temperature lattice calculations,including the study of the nature of the deconfinement transition in QCD, equation of state, screening of static quarks and meson spectral functions.

  5. Highly excited and exotic meson spectroscopy from lattice QCD

    SciTech Connect

    Christopher Thomas

    2011-05-01

    I will discuss recent progress in extracting highly excited and exotic meson spectra using lattice QCD. New results in the light meson sector will be presented, where a combination of techniques have enabled us to confidently identify the spin of extracted states. Highlights include many states with exotic quantum numbers and, for the first time in a lattice QCD calculation, spin-four states. I will conclude with comments on future prospects.

  6. Development of an object oriented lattice QCD code "Bridge++"

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Aoki, S.; Aoyama, T.; Kanaya, K.; Matsufuru, H.; Motoki, S.; Namekawa, Y.; Nemura, H.; Taniguchi, Y.; Ukita, N.

    2014-06-01

    We are developing a new lattice QCD code set "Bridge++" aiming at extensible, readable, and portable workbench for QCD simulations, while keeping a high performance at the same time. Bridge++ covers conventional lattice actions and numerical algorithms. The code set is constructed in C++ with an object oriented programming. In this paper we describe fundamental ingredients of the code and the current status of development.

  7. QCD at nonzero chemical potential: Recent progress on the lattice

    NASA Astrophysics Data System (ADS)

    Aarts, Gert; Attanasio, Felipe; Jäger, Benjamin; Seiler, Erhard; Sexty, Dénes; Stamatescu, Ion-Olimpiu

    2016-01-01

    We summarise recent progress in simulating QCD at nonzero baryon density using complex Langevin dynamics. After a brief outline of the main idea, we discuss gauge cooling as a means to control the evolution. Subsequently we present a status report for heavy dense QCD and its phase structure, full QCD with staggered quarks, and full QCD with Wilson quarks, both directly and using the hopping parameter expansion to all orders.

  8. Lattice QCD at the physical point: simulation and analysis details

    NASA Astrophysics Data System (ADS)

    Dürr, S.; Fodor, Z.; Hoelbling, C.; Katz, S. D.; Krieg, S.; Kurth, T.; Lellouch, L.; Lippert, T.; Szabó, K. K.; Vulvert, G.

    2011-08-01

    We give details of our precise determination of the light quark masses m ud = ( m u + m d )/2 and m s in 2 + 1 flavor QCD, with simulated pion masses down to 120 MeV, at five lattice spacings, and in large volumes. The details concern the action and algorithm employed, the HMC force with HEX smeared clover fermions, the choice of the scale setting procedure and of the input masses. After an overview of the simulation parameters, extensive checks of algorithmic stability, autocorrelation and (practical) ergodicity are reported. To corroborate the good scaling properties of our action, explicit tests of the scaling of hadron masses in N f = 3 QCD are carried out. Details of how we control finite volume effects through dedicated finite volume scaling runs are reported. To check consistency with SU(2) Chiral Perturbation Theory the behavior of M π 2 /m ud and F π as a function of m ud is investigated. Details of how we use the RI/MOM procedure with a separate continuum limit of the running of the scalar density R S ( μ, μ') are given. This procedure is shown to reproduce the known value of r 0 m s in quenched QCD. Input from dispersion theory is used to split our value of m ud into separate values of m u and m d . Finally, our procedure to quantify both systematic and statistical uncertainties is discussed.

  9. The QCD equation of state with charm quarks from lattice QCD

    NASA Astrophysics Data System (ADS)

    Cheng, Michael

    Recently, there have been several calculations of the QCD equation of state (EoS) on the lattice. These calculations take into account the two light quarks and the strange quark, but have ignored the effects of the charm quark, assuming that the charm mass (mc ≈ 1300 MeV) is exponentially suppressed at the temperatures which are explored. However, future heavy ion collisions, such as those planned at the LHC, may well probe temperature regimes where the charm quarks play an important role in the dynamics of the QGP. We present a calculation of the charm quark contribution to the QCD EoS using p4-improved staggered fermions at Nt = 4, 6, 8. This calculation is done with a quenched charm quark, i.e. the relevant operators are measured using a valence charm quark mass on a 2+1 flavor gauge field background. The charm quark masses are determined by calculating charmonium masses (metac and mJ/Psi) and fixing these mesons to their physical masses. The interaction measure, pressure, energy density, and entropy density are calculated. We find that the charm contribution makes a significant contribution, even down to temperatures as low as the pseudo-critical temperature, Tc. However, there are significant scaling corrections at the lattice spacings that we use, preventing a reliable continuum extrapolation.

  10. Automated generation of lattice QCD Feynman rules

    NASA Astrophysics Data System (ADS)

    Hart, A.; von Hippel, G. M.; Horgan, R. R.; Müller, E. H.

    2009-12-01

    The derivation of the Feynman rules for lattice perturbation theory from actions and operators is complicated, especially for highly improved actions such as HISQ. This task is, however, both important and particularly suitable for automation. We describe a suite of software to generate and evaluate Feynman rules for a wide range of lattice field theories with gluons and (relativistic and/or heavy) quarks. Our programs are capable of dealing with actions as complicated as (m)NRQCD and HISQ. Automated differentiation methods are used to calculate also the derivatives of Feynman diagrams. Program summaryProgram title: HiPPY, HPsrc Catalogue identifier: AEDX_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDX_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPLv2 (see Additional comments below) No. of lines in distributed program, including test data, etc.: 513 426 No. of bytes in distributed program, including test data, etc.: 4 893 707 Distribution format: tar.gz Programming language: Python, Fortran95 Computer: HiPPy: Single-processor workstations. HPsrc: Single-processor workstations and MPI-enabled multi-processor systems Operating system: HiPPy: Any for which Python v2.5.x is available. HPsrc: Any for which a standards-compliant Fortran95 compiler is available Has the code been vectorised or parallelised?: Yes RAM: Problem specific, typically less than 1 GB for either code Classification: 4.4, 11.5 Nature of problem: Derivation and use of perturbative Feynman rules for complicated lattice QCD actions. Solution method: An automated expansion method implemented in Python (HiPPy) and code to use expansions to generate Feynman rules in Fortran95 (HPsrc). Restrictions: No general restrictions. Specific restrictions are discussed in the text. Additional comments: The HiPPy and HPsrc codes are released under the second version of the GNU General Public Licence (GPL v2). Therefore anyone is

  11. Search for the pentaquark resonance signature in lattice QCD

    SciTech Connect

    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.

  12. Search for the pentaquark resonance signature in lattice QCD

    SciTech Connect

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

    2005-07-01

    Claims concerning the possible discovery of the {theta}{sup +} pentaquark, with minimal quark content uudds, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various spin-(1/2) 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}x40 lattice in the quenched approximation. The standard lattice resonance signal of binding at quark masses near the physical regime, observed for established baryon resonances, is not observed for spin-(1/2) pentaquark states. Thus we find no evidence supporting the existence of a spin-(1/2) pentaquark resonance in quenched QCD.

  13. Search for the pentaquark resonance signature in lattice QCD

    SciTech Connect

    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.

  14. QCD THERMODYNAMICS AT ZERO AND NON-ZERO DENSITY.

    SciTech Connect

    SCHMIDT, C.

    2007-07-03

    We present recent results on thermodynamics of QCD with almost physical light quark masses and a physical strange quark mass value. These calculations have been performed with an improved staggered action especially designed for finite temperature lattice QCD. In detail we present a calculation of the transition temperature, using a combined chiral and continuum extrapolation. Furthermore we present preliminary results on the interaction measure and energy density at almost realistic quark masses. Finally we discuss the response of the pressure to a finite quark chemical potential. Within the Taylor expansion formalism we calculate quark number susceptibilities and leading order corrections to finite chemical potential. This is particularly useful for mapping out the critical region in the QCD phase diagram.

  15. Opportunities, challenges, and fantasies in lattice QCD

    NASA Astrophysics Data System (ADS)

    Wilczek, Frank

    2003-05-01

    Some important problems in quantitative QCD will certainly yield to hard work and adequate investment of resources, others appear difficult but may be accessible, and still others will require essentially new ideas. Here I identify several examples in each class.

  16. Spin-(3/2) pentaquark resonance signature in lattice QCD

    SciTech Connect

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

    2005-10-01

    The possible discovery of the {theta}{sup +} pentaquark has motivated a number of studies of its nature using lattice QCD. While all the analyses thus far have focused on spin-(1/2) states, here we report the results of the first exploratory study in quenched lattice QCD of pentaquarks with spin (3/2). For the spin-(3/2) interpolating field we use a product of the standard N and K* operators. We do not find any evidence for the standard lattice resonance signature of attraction (i.e., binding at quark masses near the physical regime) in the J{sup P}=(3/2){sup -} channel. Some evidence of binding is inferred in the isoscalar (3/2){sup +} channel at several quark masses, in accord with the standard lattice resonance signature. This suggests that this is a good candidate for the further study of pentaquarks on the lattice.

  17. QCD: results from lattice quantum chromodynamics

    SciTech Connect

    Kronfeld, Andreas S.; /Fermilab

    2006-10-01

    Quantum chromodynamics (QCD) is the modern theory of the strong force. In this theory, the main objects are quarks and gluons, which are bound by the strong force into protons, neutrons, and other particles called hadrons. In the framework of QCD, the strong nuclear force binding protons and neutrons together into nuclei is actually only a residue of the much stronger forces acting between quarks and gluons. In fact, inside the proton, even the concept of force is not very useful. Within all hadrons they have a swirl of gluons being exchanged back and forth as a manifestation of the strong force. To make matters worse, gluons can split into two, and then rejoin, or they can split into a quark-antiquark pair. Even the simplest hadron is a complex system hosting constantly interacting components. Despite this complexity, QCD is well established experimentally. This is because at short distances (or high energies), the coupling between the particles is effectively small and particles move around with relative freedom. This is called asymptotic freedom and QCD is amenable to the traditional methods of quantum field theory in this regime. High-energy experiments have tested and confirmed QCD in this realm, which led to the 2004 Nobel Prize in Physics for Drs. David Gross, David Politzer, and Frank Wilczek, the theorists who provided the theory for short-range QCD and asymptotic freedom.

  18. Uncertainty quantification in lattice QCD calculations for nuclear physics

    SciTech Connect

    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.

  19. Equation of state in two-, three-, and four-color QCD at nonzero temperature and density

    NASA Astrophysics Data System (ADS)

    Gorda, Tyler; Romatschke, Paul

    2015-07-01

    We calculate the equation of state at nonzero temperature and density from first principles in two-, three-, and four-color QCD with two fermion flavors in the fundamental and two-index, antisymmetric representation. By matching low-energy results (from a "hadron resonance gas") to high-energy results from (resummed) perturbative QCD, we obtain results for the pressure and trace anomaly that are in quantitative agreement with full lattice-QCD studies for three colors at zero chemical potential. Our results for nonzero chemical potential at zero temperature constitute predictions for the equation of state in QCD-like theories that can be tested by traditional lattice studies for two-color QCD with two fundamental fermions and four-color QCD with two two-index, antisymmetric fermions. We find that the speed of sound squared at zero temperature can exceed 1 /3 , which may be relevant for the phenomenology of high-mass neutron stars.

  20. Spontaneous supersymmetry breaking in two dimensional lattice super QCD

    DOE PAGESBeta

    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

  1. Spontaneous supersymmetry breaking in two dimensional lattice super QCD

    SciTech Connect

    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 spontaneously when Nf < Nc in agreement with theoretical expectations.

  2. Quest for More Information from Lattice QCD Simulations

    NASA Astrophysics Data System (ADS)

    de Forcrand, P.; García Pérez, M.; Hashimoto, T.; Hioki, S.; Matsufuru, H.; Miyamura, O.; Umeda, T.; Nakamura, A.; Stamatescu, I.-O.; Tago, Y.; Takaishi, T.

    Lattice QCD is one of the most powerful tools to study the non-perturbative nature of the strong interaction. Although much information has been obtained so far to understand QCD, the computational cost becomes higher and higher as we calculate on finer lattices; simulations near the continuum are still far beyond. We report the progress on (1) renormalization group (RG) improved actions and (2) anisotropic lattice, which QCD-TARO group has developed and studied in order to get more information from the simulations on the present computers. RG improved actions were proposed and studied by Wilson and Iwasaki to remove discretization effects for long distance observables. We have studied 1× 1 + 1× 2 type actions, which includes Wilson, Symanzik and Iwasaki ones, by the strong and weak coupling expansions and Monte Carlo RG method. We have calculated RG flow and obtained a new effective β-function. Anisotropic lattice, where the temporal lattice spacing is smaller than that along the spatial one, makes us possible to perform finer resolution measurements in the temporal direction. This is especially useful at the finite temperature, where the temporal lattice size is limited. We have calculated meson pole and screening masses. We have found they behave in a different manner as a function of T.

  3. Hadron interactions and exotic hadrons from lattice QCD

    NASA Astrophysics Data System (ADS)

    Ikeda, Yoichi

    2014-09-01

    One of the interesting subjects in hadron physics is to look for the multiquark configurations. One of candidates is the H-dibaryon (udsuds), and the possibility of the bound H-dibaryon has been recently studied from lattice QCD. We also extend the HAL QCD method to define potentials on the lattice between baryons to meson-meson systems including charm quarks to search for the bound tetraquark Tcc (ud c c) and Tcs (ud c s). In the presentation, after reviewing the HAL QCD method, we report the results on the H-dibaryon, the tetraquark Tcc (ud c c) and Tcs (ud c s), where we have employed the relativistic heavy quark action to treat the charm quark dynamics with pion masses, mπ = 410, 570, 700 MeV.

  4. Nucleon Generalized Parton Distributions from Full Lattice QCD

    SciTech Connect

    Robert Edwards; Philipp Haegler; David Richards; John Negele; Konstantinos Orginos; Wolfram Schroers; Jonathan Bratt; Andrew Pochinsky; Michael Engelhardt; George Fleming; Bernhard Musch; Dru Renner

    2007-07-03

    We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N_f=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm)^3.

  5. Quark-gluon plasma phenomenology from anisotropic lattice QCD

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  6. Nucleon Axial Charge in Full Lattice QCD

    SciTech Connect

    Edwards, R.G.; Richards, D.G.; Fleming, G.T.; Haegler, Ph.; Negele, J.W.; Pochinsky, A.V.; Orginos, K.; Renner, D.B.; Schroers, W.

    2006-02-10

    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){sup 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 7% statistical errors.

  7. The K+ K+ scattering length from Lattice QCD

    SciTech Connect

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

    2007-09-11

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

  8. Charmonium excited state spectrum in lattice QCD

    SciTech Connect

    Jozef Dudek; Robert Edwards; Nilmani Mathur; David Richards

    2008-02-01

    Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpolating field can give additional spin-assignment information, even at a single lattice spacing, via the overlap factors of interpolating field and state. Excited state masses are systematically high with respect to quark potential model predictions and, where they exist, experimental states. We conclude that this is most likely a result of the quenched approximation.

  9. N* Spectroscopy from Lattice QCD: The Roper Explained

    NASA Astrophysics Data System (ADS)

    Leinweber, Derek; Kamleh, Waseem; Kiratidis, Adrian; Liu, Zhan-Wei; Mahbub, Selim; Roberts, Dale; Stokes, Finn; Thomas, Anthony W.; Wu, Jiajun

    This brief review focuses on the low-lying even- and odd-parity excitations of the nucleon obtained in recent lattice QCD calculations. Commencing with a survey of the 2014-15 literature we'll see that results for the first even-parity excitation energy can differ by as much as 1 GeV, a rather unsatisfactory situation. Following a brief review of the methods used to isolate excitations of the nucleon in lattice QCD, and drawing on recent advances, we'll see how a consensus on the low-lying spectrum has emerged among many different lattice groups. To provide insight into the nature of these states we'll review the wave functions and electromagnetic form factors that are available for a few of these states. Consistent with the Luscher formalism for extracting phase shifts from finite volume spectra, the Hamiltonian approach to effective field theory in finite volume can provide guidance on the manner in which physical quantities manifest themselves in the finite volume of the lattice. With this insight, we will address the question; Have we seen the Roper in lattice QCD?

  10. Bs→Kℓν form factors from lattice QCD

    NASA Astrophysics Data System (ADS)

    Bouchard, C. M.; Lepage, G. Peter; Monahan, Christopher; Na, Heechang; Shigemitsu, Junko

    2014-09-01

    We report the first lattice QCD calculation of the form factors for the standard model tree-level decay Bs→K ℓν. In combination with future measurement, this calculation will provide an alternative exclusive semileptonic determination of |Vub|. We compare our results with previous model calculations, make predictions for differential decay rates and branching fractions, and predict the ratio of differential branching fractions between Bs→Kτν and Bs→Kμν. We also present standard model predictions for differential decay rate forward-backward asymmetries and polarization fractions and calculate potentially useful ratios of Bs→K form factors with those of the fictitious Bs→ηs decay. Our lattice simulations utilize nonrelativistic QCD b and highly improved staggered light quarks on a subset of the MILC Collaboration 2+1 asqtad gauge configurations, including two lattice spacings and a range of light quark masses.

  11. Recent lattice QCD results on nucleon structure

    SciTech Connect

    Konstantinos Orginos

    2006-07-01

    I review recent developments in lattice calculations of nucleon structure. In particular, I cover the calculations of nucleon matrix elements related to generalized parton distribution functions, structure functions and form factors.

  12. Calculation of hadronic matrix elements using lattice QCD

    SciTech Connect

    Gupta, R.

    1993-08-01

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

  13. Lattice QCD computations: Recent progress with modern Krylov subspace methods

    SciTech Connect

    Frommer, A.

    1996-12-31

    Quantum chromodynamics (QCD) is the fundamental theory of the strong interaction of matter. In order to compare the theory with results from experimental physics, the theory has to be reformulated as a discrete problem of lattice gauge theory using stochastic simulations. The computational challenge consists in solving several hundreds of very large linear systems with several right hand sides. A considerable part of the world`s supercomputer time is spent in such QCD calculations. This paper presents results on solving systems for the Wilson fermions. Recent progress is reviewed on algorithms obtained in cooperation with partners from theoretical physics.

  14. Elimination of spurious lattice fermion solutions and noncompact lattice QCD

    SciTech Connect

    Lee, T.D.

    1997-09-22

    It is well known that the Dirac equation on a discrete hyper-cubic lattice in D dimension has 2{sup D} degenerate solutions. The usual method of removing these spurious solutions encounters difficulties with chiral symmetry when the lattice spacing l {ne} 0, as exemplified by the persistent problem of the pion mass. On the other hand, we recall that in any crystal in nature, all the electrons do move in a lattice and satisfy the Dirac equation; yet there is not a single physical result that has ever been entangled with a spurious fermion solution. Therefore it should not be difficult to eliminate these unphysical elements. On a discrete lattice, particle hop from point to point, whereas in a real crystal the lattice structure in embedded in a continuum and electrons move continuously from lattice cell to lattice cell. In a discrete system, the lattice functions are defined only on individual points (or links as in the case of gauge fields). However, in a crystal the electron state vector is represented by the Bloch wave functions which are continuous functions in {rvec {gamma}}, and herein lies one of the essential differences.

  15. Two-photon decays of η _c from lattice QCD

    NASA Astrophysics Data System (ADS)

    Chen, Ting; Chen, Ying; Gong, Ming; Lei, Yu-Hong; Li, Ning; Liu, Chuan; Liu, Yu-Bin; Liu, Zhaofeng; Ma, Jian-Ping; Qiu, Wei-Feng; Wang, Zhan-Lin; Zhang, Jian-Bo

    2016-07-01

    We present an exploratory lattice study for the two-photon decay of η _c using N_f=2 twisted mass lattice QCD gauge configurations generated by the European Twisted Mass Collaboration. Two different lattice spacings of a=0.067 fm and a=0.085 fm are used in the study, both of which are of physical size of 2 fm. The decay widths are found to be 1.025(5) KeV for the coarser lattice and 1.062(5) KeV for the finer lattice, respectively, where the errors are purely statistical. A naive extrapolation toward the continuum limit yields Γ ˜eq 1.122(14) KeV, which is smaller than the previous quenched result and most of the current experimental results. Possible reasons are discussed.

  16. Excited state baryon spectroscopy from lattice QCD

    SciTech Connect

    Robert G. Edwards; Dudek, Jozef J.; Richards, David G.; Wallace, Stephen J.

    2011-10-31

    Here, we present a calculation of the Nucleon and Delta excited state spectrum on dynamical anisotropic clover lattices. A method for operator construction is introduced that allows for the reliable identification of the continuum spins of baryon states, overcoming the reduced symmetry of the cubic lattice. Using this method, we are able to determine a spectrum of single-particle states for spins up to and including $J = 7/2$, of both parities, the first time this has been achieved in a lattice calculation. We find a spectrum of states identifiable as admixtures of $SU(6) Ⓧ O(3)$ representations and a counting of levels that is consistent with the non-relativistic $qqq$ constituent quark model. This dense spectrum is incompatible with quark-diquark model solutions to the "missing resonance problem" and shows no signs of parity doubling of states.

  17. Excited state baryon spectroscopy from lattice QCD

    DOE PAGESBeta

    Robert G. Edwards; Dudek, Jozef J.; Richards, David G.; Wallace, Stephen J.

    2011-10-31

    Here, we present a calculation of the Nucleon and Delta excited state spectrum on dynamical anisotropic clover lattices. A method for operator construction is introduced that allows for the reliable identification of the continuum spins of baryon states, overcoming the reduced symmetry of the cubic lattice. Using this method, we are able to determine a spectrum of single-particle states for spins up to and including $J = 7/2$, of both parities, the first time this has been achieved in a lattice calculation. We find a spectrum of states identifiable as admixtures of $SU(6) Ⓧ O(3)$ representations and a counting ofmore » levels that is consistent with the non-relativistic $qqq$ constituent quark model. This dense spectrum is incompatible with quark-diquark model solutions to the "missing resonance problem" and shows no signs of parity doubling of states.« less

  18. QCD AT HIGH PARTON DENSITY

    SciTech Connect

    KOVCHEGOV,Y.V.

    2000-04-25

    The authors derive an equation determining the small-x evolution of the F{sub 2} structure function of a large nucleus which resumes a cascade of gluons in the leading logarithmic approximation using Mueller's color dipole model. In the traditional language it corresponds to resummation of the pomeron fan diagrams, originally conjectured in the GLR equation. The authors show that the solution of the equation describes the physics of structure functions at high partonic densities, thus allowing them to gain some understanding of the most interesting and challenging phenomena in small-x physics--saturation.

  19. Gauge Configurations for Lattice QCD from The Gauge Connection

    DOE Data Explorer

    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)

  20. A study of Θ+(ududs¯) in lattice QCD

    NASA Astrophysics Data System (ADS)

    Chiu, Ting-Wai; Hsieh, Tung-Han

    2005-03-01

    We investigate the mass spectrum of the pentaquark baryon ( ududs¯) in quenched lattice QCD with exact chiral symmetry. Using 3 different interpolating operators, we measure the 3×3 correlation matrix and obtain the eigenvalues A(t) with ± parity. For odd parity states, A(t) deviates from pure exponential decay even at large t, which implies that it cannot be a resonance with narrow decay width, thus is ruled out as a candidate of Θ(1540). For even parity states, they behave like usual resonances seen in quenched lattice QCD, and the mass of the lowest lying J=1/2 state is determined to be 1583 ± 121 MeV.

  1. Baryon Spectroscopy and Operator Construction in Lattice QCD

    SciTech Connect

    S. Basak; I. Sato; S. Wallace; R. Edwards; D. Richards; R. Fiebig; G. Fleming; U. Heller; C. Morningstar

    2004-07-01

    This talk describes progress at understanding the properties of the nucleon and its excitations from lattice QCD. I begin with a review of recent lattice results for the lowest-lying states of the excited baryon spectrum. The need to approach physical values of the light quark masses is emphasized, enabling the effects of the pion cloud to be revealed. I then outline the development of techniques that will enable the extraction of the masses of the higher resonances. I will describe how such calculations provide insight into the structure of the hadrons, and enable comparison both with experiment, and with QCD-inspired pictures of hadron structure, such as calculations in the limit of large N{sub c}.

  2. Proton decay matrix elements from lattice QCD

    SciTech Connect

    Aoki, Yasumichi; Shintani, Eigo; Collaboration: RBC Collaboration; UKQCD Collaboration

    2012-07-27

    We report on the calculation of the matrix elements of nucleon to pseudoscalar decay through a three quark operator, a part of the low-energy, four-fermion, baryon-number-violating operator originating from grand unified theories. The direct calculation of the form factors using domain-wall fermions on the lattice, incorporating the u, d and s sea-quarks effects yields the results with all the relevant systematic uncertainties controlled for the first time.

  3. Nucleon Distribution Amplitudes from Lattice QCD

    SciTech Connect

    Goeckeler, Meinulf; Kaltenbrunner, Thomas; Warkentin, Nikolaus; Horsley, Roger; Zanotti, James M.; Nakamura, Yoshifumi; Pleiter, Dirk; Schierholz, Gerrit; Rakow, Paul E. L.; Schaefer, Andreas; Stueben, Hinnerk

    2008-09-12

    We calculate low moments of the leading-twist and next-to-leading-twist nucleon distribution amplitudes on the lattice using two flavors of clover fermions. The results are presented in the MS scheme at a scale of 2 GeV and can be immediately applied in phenomenological studies. We find that the deviation of the leading-twist nucleon distribution amplitude from its asymptotic form is less pronounced than sometimes claimed in the literature.

  4. Weak coupling tests of lattice QCD

    SciTech Connect

    Kovacs, E.

    1984-01-01

    For many arbitrary lattices with arbitrary SU(N) actions, the perturbative value of ..lambda../sub latt//..lambda../sub MOM/ can be estimated from the Monte Carlo data at weak coupling by analyzing the perturbative expansions for various Wilson loop ratios. Here, general loop ratios including those of polygons and parallelograms are considered. The lowest order perturbative expansions are calculated and some applications to the Monte Carlo data are presented.

  5. Diquark mass differences from unquenched lattice QCD

    NASA Astrophysics Data System (ADS)

    Bi, Yujiang; Cai, Hao; Chen, Ying; Gong, Ming; Liu, Zhaofeng; Qiao, Hao-Xue; Yang, Yi-Bo

    2016-07-01

    We calculate diquark correlation functions in the Landau gauge on the lattice using overlap valence quarks and 2+1-flavor domain wall fermion configurations. Quark masses are extracted from the scalar part of quark propagators in the Landau gauge. The scalar diquark quark mass difference and axial vector scalar diquark mass difference are obtained for diquarks composed of two light quarks and of a strange and a light quark. The light sea quark mass dependence of the results is examined. Two lattice spacings are used to check the discretization effects. The coarse and fine lattices are of sizes 243 × 64 and 323 × 64 with inverse spacings 1/a = 1.75(4) GeV and 2.33(5) GeV, respectively. Supported by National Science Foundation of China (11575197, 10835002, 11405178, 11335001), joint funds of NSFC (U1232109), MG and ZL are partially supported by the Youth Innovation Promotion Association of CAS (2015013, 2011013), YC and ZL acknowledge support of NSFC and DFG (CRC110)

  6. Phase structure of two-color QCD at real and imaginary chemical potentials: Lattice simulations and model analyses

    NASA Astrophysics Data System (ADS)

    Makiyama, Takahiro; Sakai, Yuji; Saito, Takuya; Ishii, Masahiro; Takahashi, Junichi; Kashiwa, Kouji; Kouno, Hiroaki; Nakamura, Atsushi; Yahiro, Masanobu

    2016-01-01

    We investigate the phase structure of two-color QCD at both real and imaginary chemical potentials (μ ), performing lattice simulations and analyzing the data with the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. Lattice QCD simulations are done on an 83×4 lattice with the clover-improved two-flavor Wilson fermion action and the renormalization-group-improved Iwasaki gauge action. We test the analytic continuation of physical quantities from imaginary μ to real μ by comparing lattice QCD results calculated at real μ with the results of an analytic function, the coefficients of which are determined from lattice QCD results at imaginary μ . We also test the validity of the PNJL model by comparing model results with lattice QCD ones. The PNJL model is good in the deconfinement region, but less accurate in the transition and confinement regions. This problem is cured by introducing the baryon degree of freedom to the model. It is also found that the vector-type four-quark interaction is necessary to explain lattice data on the quark number density.

  7. Excited and exotic charmonium spectroscopy from lattice QCD

    SciTech Connect

    Liu, L; Peardon, M J; Ryan, S M; Thomas, C; Vilaseca, P; Dudek, J; Edwards, R; Joo, B; Richards, D G

    2012-12-01

    We study the charmonium spectrum in full QCD on anisotropic lattices generated by Hadron Spectrum Collaboration. We adopt a large basis of interpolating operators to extract the excited charmonium states using the variational method. A detailed spectrum of excited charmonium mesons in many J{sup PC} channels is obtained. Some exotic hybrid states ( with J{sup PC} = 0{sup +-} , 1{sup -+} , 2{sup +-}) are also studied

  8. Hyperon-Nulceon Scattering from Fully-Dynamical Lattice QCD

    SciTech Connect

    Silas Beane; Paulo Bedaque; Thomas Luu; Konstantinos Orginos; Elizabetta Pallante; Assumpta Parreno; Martin Savage

    2007-10-01

    We present results of the first fully-dynamical lattice QCD determination of hyperon-nucleon scattering. One s-wave phase shift was determined for n{Lambda} scattering in both spin-channels at pion masses of 350, 490, and 590 MeV, and for n{Sigma}^- scattering in both spin channels at pion masses of 490, and 590 MeV. The calculations were performed with domain-wall valence quarks on dynamical, staggered gauge configurations with a lattice spacing of b ~0.125 fm.

  9. Transverse Momentum-Dependent Parton Distributions From Lattice QCD

    SciTech Connect

    Michael Engelhardt, Bernhard Musch, Philipp Haegler, Andreas Schaefer

    2012-12-01

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

  10. Nucleon generalized parton distributions from full lattice QCD

    SciTech Connect

    Haegler, Ph.; Musch, B.; Schroers, W.; Edwards, R. G.; Richards, D. G.; Engelhardt, M.; Fleming, G. T.; Orginos, K.; Renner, D. B.

    2008-05-01

    We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N{sub f}=2+1 lattice QCD using domain-wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm){sup 3}, for a lattice spacing of 0.124 fm. We use perturbative renormalization at one-loop level with an improvement based on the nonperturbative renormalization factor for the axial vector current, and only connected diagrams are included in the isosinglet channel.

  11. Charmed meson decay constants in three-flavor lattice QCD

    SciTech Connect

    Aubin, C.; Bernard, C.; DeTar, C.; Di Pierro, M.; Freeland, Elizabeth D.; Gottlieb, Steven; Heller, U.M.; Hetrick, J.E.; El-Khadra, Aida X.; Kronfeld, Andreas S.; Levkova, L.; Mackenzie, P.B.; Menscher, D.; Maresca, F.; Nobes, M.; Okamoto, M.; Renner, D.B.; Simone, J.; Sugar, R.; Toussaint, D.; Trottier, H.D.; /Art Inst. of Chicago /Columbia U. /Washington U., St. Louis /Utah U. /DePaul U. /Indiana U. /APS, New York /U. Pacific, Stockton /Illinois U., Urbana /Fermilab /Cornell U., LEPP /Arizona U. /UC, Santa Barbara /Simon Fraser U.

    2005-06-01

    The authors present the first lattice QCD calculation with realistic sea quark content of the D{sup +}-meson decay constant f{sub D+}. They use the MILC Collaboration's publicly available ensembles of lattice gauge fields, which have a quark sea with two flavors (up and down) much lighter than a third (strange). They obtain f{sub D+} = 201 {+-} 3 {+-} 17 MeV, where the errors are statistical and a combination of systematic errors. They also obtain f{sub D{sub s}} = 249 {+-} 3 {+-} 16 MeV for the D{sub s} meson.

  12. Charmed tetraquarks Tcc and Tcs from dynamical lattice QCD simulations

    NASA Astrophysics Data System (ADS)

    Ikeda, Yoichi; Charron, Bruno; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Inoue, Takashi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji

    2014-02-01

    Charmed tetraquarks Tcc=(ccubardbar) and Tcs=(csubardbar) are studied through the S-wave meson-meson interactions, D-D, Kbar-D, D-D* and Kbar-D*, on the basis of the (2+1)-flavor lattice QCD simulations with the pion mass mπ≃410, 570 and 700 MeV. For the charm quark, the relativistic heavy quark action is employed to treat its dynamics on the lattice. Using the HAL QCD method, we extract the S-wave potentials in lattice QCD simulations, from which the meson-meson scattering phase shifts are calculated. The phase shifts in the isospin triplet (I=1) channels indicate repulsive interactions, while those in the I=0 channels suggest attraction, growing as mπ decreases. This is particularly prominent in the Tcc (JP=1+,I=0) channel, though neither bound state nor resonance are found in the range mπ=410-700 MeV. We make a qualitative comparison of our results with the phenomenological diquark picture.

  13. Rho resonance parameters from lattice QCD

    NASA Astrophysics Data System (ADS)

    Guo, Dehua; Alexandru, Andrei; Molina, Raquel; Döring, Michael

    2016-08-01

    We perform a high-precision calculation of the phase shifts for π -π scattering in the I =1 , J =1 channel in the elastic region using elongated lattices with two mass-degenerate quark flavors (Nf=2 ). We extract the ρ resonance parameters using a Breit-Wigner fit at two different quark masses, corresponding to mπ=226 MeV and mπ=315 MeV , and perform an extrapolation to the physical point. The extrapolation is based on a unitarized chiral perturbation theory model that describes well the phase shifts around the resonance for both quark masses. We find that the extrapolated value, mρ=720 (1 )(15 ) MeV , is significantly lower that the physical rho mass and we argue that this shift could be due to the absence of the strange quark in our calculation.

  14. Anomalous effects in lattice QCD with staggered fermions

    NASA Astrophysics Data System (ADS)

    Kaehler, Adrian Leslie

    1999-12-01

    In this thesis we investigate the role of the anomaly in lattice QCD, paying particular attention to the role of topology, and the effects of suppressing the fermion determinant in numerical simulations. QCD with staggered fermions is studied just above the deconfining phase transition, where anomalous effects are expected to contribute a residual breaking of chiral symmetry, and where that residual breaking is expected to manifest itself as a source of unphysical divergences in the quenched approximation. These divergences are expected to arise from exact zero eigenvalues in the spectrum of the Dirac operator, which would be suppressed by the fermion determinant in an un-quenched simulation. The signal for this anomalous divergence is investigated first in a semi-classical environment in which smooth backgrounds allow us to better understand the manner in which these effects appear in the staggered fermion formulation. An older study on a 163 x 4 lattice is revisited and a new study is conducted on a 323 x 8 lattice. No signal is found in either study. An exploratory study on a 323 x 12 lattice is presented. In this case however, the spatial volume is insufficient to avoid tunneling into the confined phase, and other Z 3 phases in which there are known to be small eigenvalues resulting from chiral symmetry breaking, unrelated to the anomaly.

  15. A Framework for Lattice QCD Calculations on GPUs

    SciTech Connect

    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.

  16. Spectroscopy of triply charmed baryons from lattice QCD

    SciTech Connect

    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.

  17. Gluonic excitation of nonexotic hybrid charmonium from lattice QCD

    SciTech Connect

    Luo Xiangqian; Liu Yan

    2006-08-01

    The ground and first excited states of the hybrid charmonium ccg, with nonexotic quantum numbers J{sup PC}=0{sup -+}, 1{sup --}, and 1{sup ++} are investigated using quenched lattice QCD. The excited states are completely ignored in the literature. However, we observe strong gluonic radial excitations in the first excited states; We find their masses are completely different from the first excited states of the corresponding conventional charmonium. Their relevance to the recent discovery of the Y(4260) state and future experimental search for other states are also discussed.

  18. Quarkonium-nucleus bound states from lattice QCD

    SciTech Connect

    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.

  19. Quark-gluon vertex model and lattice-QCD data

    SciTech Connect

    Bhagwat, M.S.; Tandy, P.C.

    2004-11-01

    A model for the dressed-quark-gluon vertex, at zero gluon momentum, is formed from a nonperturbative extension of the two Feynman diagrams that contribute at one loop in perturbation theory. The required input is an existing ladder-rainbow model Bethe-Salpeter kernel from an approach based on the Dyson-Schwinger equations; no new parameters are introduced. The model includes an Ansatz for the triple-gluon vertex. Two of the three vertex amplitudes from the model provide a pointwise description of the recent quenched-lattice-QCD data. An estimate of the effects of quenching is made.

  20. Two Photon Decays of Charmonia from Lattice QCD

    SciTech Connect

    Jozef Dudek; Robert Edwards

    2006-07-12

    We make the first calculation in lattice QCD of two-photon decays of mesons. Working in the charmonium sector, using the LSZ reduction to relate a photon to a sum of hadronic vector eigenstates, we compute form-factors in both the space-like and time-like domains for the transitions {eta}{sub c} {yields} {gamma}*{gamma}* and {chi}{sub c0} {yields} {gamma}*{gamma}*. At the on-shell point we find approximate agreement with experimental world-average values.

  1. Evidence for a bound H-dibaryon using lattice QCD

    SciTech Connect

    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.

  2. Multi-meson systems in lattice QCD / Many-body QCD

    SciTech Connect

    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

  3. Transverse momentum-dependent parton distribution functions from lattice QCD

    SciTech Connect

    Michael Engelhardt, Philipp Haegler, Bernhard Musch, John Negele, Andreas Schaefer

    2012-12-01

    Transverse momentum-dependent parton distributions (TMDs) relevant for semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process can be defined in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection. Starting from such a definition, a scheme to determine TMDs in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are obtained using ensembles at the pion masses 369MeV and 518MeV, focusing in particular on the dependence of these shifts on the staple extent and a Collins-Soper-type evolution parameter quantifying proximity of the staples to the light cone.

  4. Applications of lattice QCD techniques for condensed matter systems

    NASA Astrophysics Data System (ADS)

    Buividovich, P. V.; Ulybyshev, M. V.

    2016-08-01

    We review the application of lattice QCD techniques, most notably the Hybrid Monte Carlo (HMC) simulations, to first-principle study of tight-binding models of crystalline solids with strong inter-electron interactions. After providing a basic introduction into the HMC algorithm as applied to condensed matter systems, we review HMC simulations of graphene, which in the recent years have helped to understand the semimetal behavior of clean suspended graphene at the quantitative level. We also briefly summarize other novel physical results obtained in these simulations. Then we comment on the applicability of hybrid Monte Carlo to topological insulators and Dirac and Weyl semimetals and highlight some of the relevant open physical problems. Finally, we also touch upon the lattice strong-coupling expansion technique as applied to condensed matter systems.

  5. Excited and exotic charmonium spectroscopy from lattice QCD

    SciTech Connect

    Liuming Liu, Graham Moir, Michael Peardon, Sinead Ryan, Christopher Thomas, Pol Vilaseca, Jozef Dudek, Robert Edwards, Balint Joo, David Richards

    2012-07-01

    We present a spectrum of highly excited charmonium mesons up to around 4.5 GeV calculated using dynamical lattice QCD. Employing novel computational techniques and the variational method with a large basis of carefully constructed operators, we extract and reliably identify the continuum spin of an extensive set of excited states, states with exotic quantum numbers (0+-, 1-+, 2+-) and states with high spin. Calculations are performed on two lattice volumes with pion mass ? 400 MeV and the mass determinations have high statistical precision even for excited states. We discuss the results in light of experimental observations, identify the lightest 'supermultiplet' of hybrid mesons and comment on the phenomenological implications of the spectrum of exotic mesons.

  6. Toward the excited isoscalar meson spectrum from lattice QCD

    SciTech Connect

    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, 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.

  7. Toward the excited isoscalar meson spectrum from lattice QCD

    DOE PAGESBeta

    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

  8. Evidence for a bound H-dibaryon from lattice QCD

    SciTech Connect

    Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A

    2011-04-01

    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_\\pi < 389 MeV. Extrapolating the results of lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of L < 2.0, 2.5, 3.0 and 3.9 fm at a spatial lattice spacing of b_s < 0.123 fm, we find an H-dibaryon bound by B_ ^H = 16.6±2.1±4.6 MeV at a pion mass of m_\\pi < 389 MeV.

  9. Bootstrap bound for conformal multi-flavor QCD on lattice

    NASA Astrophysics Data System (ADS)

    Nakayama, Yu

    2016-07-01

    The recent work by Iha et al. shows an upper bound on mass anomalous dimension γ m of multi-flavor massless QCD at the renormalization group fixed point from the conformal bootstrap in SU( N F ) V symmetric conformal field theories under the assumption that the fixed point is realizable with the lattice regularization based on staggered fermions. We show that the almost identical but slightly stronger bound applies to the regularization based on Wilson fermions (or domain wall fermions) by studying the conformal bootstrap in SU( N f ) L × SU( N f ) R symmetric conformal field theories. For N f = 8, our bound implies γ m < 1 .31 to avoid dangerously irrelevant operators that are not compatible with the lattice symmetry.

  10. Lattice QCD determination of patterns of excited baryon states

    SciTech Connect

    Subhasish Basak; Robert Edwards; George Fleming; Keisuke Juge; Adam Lichtl; Colin Morningstar; David Richards; Ikuro Sato; Stephen Wallace

    2007-10-01

    Energies for excited isospin I = 1/2 and I = 3/2 states that include the nucleon and Delta families of baryons are computed using quenched, anisotropic lattices. Baryon interpolating field operators that are used include nonlocal operators that provide G2 irreducible representations of the octahedral group. The decomposition of spin 5/2 or higher spin states is realized for the first time in a lattice QCD calculation. We observe patterns of degenerate energies in the irreducible representations of the octahedral group that correspond to the subduction of the continuum spin 5/2 or higher. The overall pattern of low-lying excited states corresponds well to the pattern of physical states subduced to the irreducible representations of the octahedral group.

  11. First Calculation of Hyperon Axial Couplings from Lattice QCD

    SciTech Connect

    Huey-Wen Lin; Konstantinos Orginos

    2007-12-06

    In this work, we report the first lattice calculation of the hyperon axial couplings, using the 2+1-flavor MILC configurations and domain-wall fermion valence quarks. Both the $\\Sigma$ and $\\Xi$ axial couplings are for the first time done in lattice QCD, and we find the numbers with greater precision than previous chiral perturbation theory and large-$N_c$ theory estimate: $g_{\\Sigma\\Sigma} = 0.450(21)_{\\rm stat}(22)_{\\rm syst}$ and $g_{\\Xi\\Xi} = -0.277(15)_{\\rm stat}(16)_{\\rm syst}$. As a side product, we also determine the low-energy chiral parameters $D$ and $F$ extracted from these coupling constants: $D=0.715(6)_{\\rm stat}(6)_{\\rm syst}$ and $F=0.453(5)_{\\rm stat}(5)_{\\rm syst}$.

  12. Towards the petaflop for Lattice QCD simulations the PetaQCD project

    NASA Astrophysics Data System (ADS)

    Anglès d'Auriac, Jean-Christian; Barthou, Denis; Becirevic, Damir; Bilhaut, René; Bodin, François; Boucaud, Philippe; Brand-Foissac, Olivier; Carbonell, Jaume; Eisenbeis, Christine; Gallard, Pascal; Grosdidier, Gilbert; Guichon, Pierre; Honoré, Pierre-François; Le Meur, Guy; Pène, Olivier; Rilling, Louis; Roudeau, Patrick; Seznec, André; Stocchi, Achille; Touze, François

    2010-04-01

    The study and design of a very ambitious petaflop cluster exclusively dedicated to Lattice QCD simulations started in early '08 among a consortium of 7 laboratories (IN2P3, CNRS, INRIA, CEA) and 2 SMEs. This consortium received a grant from the French ANR agency in July '08, and the PetaQCD project kickoff took place in January '09. Building upon several years of fruitful collaborative studies in this area, the aim of this project is to demonstrate that the simulation of a 256 x 1283 lattice can be achieved through the HMC/ETMC software, using a machine with efficient speed/cost/reliability/power consumption ratios. It is expected that this machine can be built out of a rather limited number of processors (e.g. between 1000 and 4000), although capable of a sustained petaflop CPU performance. The proof-of-concept should be a mock-up cluster built as much as possible with off-the-shelf components, and 2 particularly attractive axis will be mainly investigated, in addition to fast all-purpose multi-core processors: the use of the new brand of IBM-Cell processors (with on-chip accelerators) and the very recent Nvidia GP-GPUs (off-chip co-processors). This cluster will obviously be massively parallel, and heterogeneous. Communication issues between processors, implied by the Physics of the simulation and the lattice partitioning, will certainly be a major key to the project.

  13. Sharing lattice QCD data over a widely distributed file system

    NASA Astrophysics Data System (ADS)

    Amagasa, T.; Aoki, S.; Aoki, Y.; Aoyama, T.; Doi, T.; Fukumura, K.; Ishii, N.; Ishikawa, K.-I.; Jitsumoto, H.; Kamano, H.; Konno, Y.; Matsufuru, H.; Mikami, Y.; Miura, K.; Sato, M.; Takeda, S.; Tatebe, O.; Togawa, H.; Ukawa, A.; Ukita, N.; Watanabe, Y.; Yamazaki, T.; Yoshie, T.

    2015-12-01

    JLDG is a data-grid for the lattice QCD (LQCD) community in Japan. Several large research groups in Japan have been working on lattice QCD simulations using supercomputers distributed over distant sites. The JLDG provides such collaborations with an efficient method of data management and sharing. File servers installed on 9 sites are connected to the NII SINET VPN and are bound into a single file system with the GFarm. The file system looks the same from any sites, so that users can do analyses on a supercomputer on a site, using data generated and stored in the JLDG at a different site. We present a brief description of hardware and software of the JLDG, including a recently developed subsystem for cooperating with the HPCI shared storage, and report performance and statistics of the JLDG. As of April 2015, 15 research groups (61 users) store their daily research data of 4.7PB including replica and 68 million files in total. Number of publications for works which used the JLDG is 98. The large number of publications and recent rapid increase of disk usage convince us that the JLDG has grown up into a useful infrastructure for LQCD community in Japan.

  14. Vector and scalar charmonium resonances with lattice QCD

    DOE PAGESBeta

    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

  15. Vector and scalar charmonium resonances with lattice QCD

    SciTech Connect

    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.

  16. QCD with 2 light quark flavours: Thermodynamics on a 16[sup 3] [times] 8 lattice and glueballs and topological charge on a 16[sup 3] [times] 32 lattice

    SciTech Connect

    Sinclair, D.K.

    1992-11-20

    The HTMCGC collaboration has been simulating lattice QCD with two light staggered quarks with masses m[sub q] = 0.0125 and also m[sub q] = 0.00625 on a 16[sup 3] [times] 8 lattice. We have been studying the behavior of the transition from hadronic matter to a quark-gluon plasma and the properties of that plasma. We have been measuring entropy densities, Debye and hadronic screening lengths, the spacial string tension and topological susceptibility in addition to the standard order parameters. The HEMCGC collaboration has simulated lattice QCD with two light staggered quarks,m[sub q] = 0.025 and m[sub q] = 0.010 on a 16[sup 3] [times] 32 lattice. We have measured the glueball spectrum and topological susceptibilities for these runs.

  17. QCD with 2 light quark flavours: Thermodynamics on a 16{sup 3} {times} 8 lattice and glueballs and topological charge on a 16{sup 3} {times} 32 lattice

    SciTech Connect

    Sinclair, D.K.; HEMCGC collaboration; HTMCGC collaboration

    1992-11-20

    The HTMCGC collaboration has been simulating lattice QCD with two light staggered quarks with masses m{sub q} = 0.0125 and also m{sub q} = 0.00625 on a 16{sup 3} {times} 8 lattice. We have been studying the behavior of the transition from hadronic matter to a quark-gluon plasma and the properties of that plasma. We have been measuring entropy densities, Debye and hadronic screening lengths, the spacial string tension and topological susceptibility in addition to the standard order parameters. The HEMCGC collaboration has simulated lattice QCD with two light staggered quarks,m{sub q} = 0.025 and m{sub q} = 0.010 on a 16{sup 3} {times} 32 lattice. We have measured the glueball spectrum and topological susceptibilities for these runs.

  18. Spectroscopy of doubly charmed baryons from lattice QCD

    SciTech Connect

    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 at⁻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.

  19. Electric Polarizability of Neutral Hadrons from Lattice QCD

    SciTech Connect

    Joe Christensen; Walter Wilcox; Frank X. Lee; Leming Zhou

    2004-08-01

    By simulating a uniform electric field on a lattice and measuring the change in the rest mass, we calculate the electric polarizability of neutral mesons and baryons using the methods of quenched lattice QCD. Specifically, we measure the electric polarizability coefficient from the quadratic response to the electric field for 10 particles: the vector mesons {rho}{sup 0} and K{sup *0}; the octet baryons n, {Sigma}{sup 0}, {Lambda}{sub o}{sup 0}, {Lambda}{sub s}{sup 0}, and {Xi}{sup 0}; and the decouplet baryons {Delta}{sup 0}, {Sigma}{sup 0}, and {Xi}{sup 0}. Independent calculations using two fermion actions were done for consistency and comparison purposes. One calculation uses Wilson fermions with a lattice spacing of a = 0.10 fm. The other uses tadpole improved Luesher-Weiss gauge fields and clover quark action with a lattice spacing a = 0.17 fm. Our results for neutron electric polarizability are compared to experiment.

  20. Finite Volume Dependence of Hadron Properties and Lattice QCD

    SciTech Connect

    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.

  1. Spectroscopy of doubly charmed baryons from lattice QCD

    NASA Astrophysics Data System (ADS)

    Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael; Hadron Spectrum Collaboration

    2015-05-01

    We present 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 1 63×128 , with inverse spacing in temporal direction at-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.

  2. Lattice QCD study of mixed systems of pions and kaons

    SciTech Connect

    William Detmold, Brian Smigielski

    2011-07-01

    The O(100) different ground state energies of N-pion and M-kaon systems for N+M <= 12 are studied in lattice QCD. These energies are then used to extract the various two- and three- body interactions that occur in these systems. These calculations are performed using one ensemble of 2+1 flavor anisotropic lattices with a spatial lattice spacing $a_s$ ~ 0.125 fm, an anisotropy factor $\\xi=a_s/a_t=3.5$, and a spatial volume $L^3\\sim (2.5\\ {\\rm fm})^3$. Particular attention is paid to additional thermal states present in the spectrum because of the finite temporal extent. The quark masses used correspond to pion and kaon masses of $m_\\pi$ ~ 383 MeV and $m_K$ ~ 537 MeV, respectively. The isospin and strangeness chemical potentials of these systems are found to be in the region where chiral perturbation theory and hadronic models predict a phase transition between a pion condensed phase and a kaon condensed phase.

  3. Improved semileptonic form factor calculations in lattice QCD

    SciTech Connect

    Evans, Richard; Bali, Gunnar; Collins, Sara

    2010-11-01

    We investigate the computational efficiency of two stochastic based alternatives to the sequential propagator method used in lattice QCD calculations of heavy-light semileptonic form factors. In the first method, we replace the sequential propagator, which couples the calculation of two of the three propagators required for the calculation, with a stochastic propagator so that the calculations of all three propagators are independent. This method is more flexible than the sequential propagator method but introduces stochastic noise. We study the noise to determine when this method becomes competitive with the sequential propagator method, and find that for any practical calculation it is competitive with or superior to the sequential propagator method. We also examine a second stochastic method, the so-called 'one-end trick', concluding it is relatively inefficient in this context. The investigation is carried out on two gauge field ensembles, using the nonperturbatively improved Wilson-Sheikholeslami-Wohlert action with N{sub f}=2 mass-degenerate sea quarks. The two ensembles have similar lattice spacings but different sea-quark masses. We use the first stochastic method to extract O(a)-improved, matched lattice results for the semileptonic form factors on the ensemble with lighter sea quarks, extracting f{sub +}(0).

  4. Lattice QCD phase diagram in and away from the strong coupling limit.

    PubMed

    de Forcrand, Ph; Langelage, J; Philipsen, O; Unger, W

    2014-10-10

    We study lattice QCD with four flavors of staggered quarks. In the limit of infinite gauge coupling, "dual" variables can be introduced, which render the finite-density sign problem mild and allow a full determination of the μ-T phase diagram by Monte Carlo simulations, also in the chiral limit. However, the continuum limit coincides with the weak coupling limit. We propose a strong-coupling expansion approach towards the continuum limit. We show first results, including the phase diagram and its chiral critical point, from this expansion truncated at next-to-leading order. PMID:25375704

  5. Medium-heavy nuclei from nucleon-nucleon interactions in lattice QCD

    NASA Astrophysics Data System (ADS)

    Inoue, Takashi; Aoki, Sinya; Charron, Bruno; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji; HAL QCD Collaboration

    2015-01-01

    On the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon forces obtained from lattice QCD simulations, the properties of the medium-heavy doubly magic nuclei such as 16O and 40Ca are investigated. We found that those nuclei are bound for the pseudoscalar meson mass MPS≃470 MeV. The mass number dependence of the binding energies, single-particle spectra, and density distributions are qualitatively consistent with those expected from empirical data at the physical point, although these hypothetical nuclei at heavy quark mass have smaller binding energies than the real nuclei.

  6. Transverse momentum-dependent parton distribution functions in lattice QCD

    SciTech Connect

    Engelhardt, Michael G.; Musch, Bernhard U.; Haegler, Philipp G.; Negele, John W.; Schaefer, Andreas

    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.

  7. Nucleon to delta electromagnetic transition form factors in lattice QCD

    SciTech Connect

    Alexandrou, C.; Koutsou, G.; Neff, H.; Negele, J. W.; Schroers, W.; Tsapalis, A.

    2008-04-15

    The electromagnetic nucleon to {delta} transition form factors are evaluated using two degenerate flavors of dynamical Wilson fermions and using dynamical sea staggered fermions with domain-wall valence quarks. The two subdominant quadrupole form factors are evaluated for the first time in full QCD to sufficient accuracy to exclude a zero value, which is taken as a signal for deformation in the nucleon-{delta} system. For the Coulomb quadrupole form factor the unquenched results begin to deviate from the quenched results at low q{sup 2} indicating that dynamical lattice results are closer to experiment. This can be taken as a first confirmation of the expected importance of pion cloud contributions on this quantity.

  8. Determination of the Lambda parameter from full lattice QCD

    SciTech Connect

    Goeckeler, M.; Horsley, R.; Irving, A.C.; Rakow, P.E.L.; Pleiter, D.; Schierholz, G.; Stueben, H.

    2006-01-01

    We present a determination of the QCD parameter {lambda} in the quenched approximation (n{sub f}=0) and for two flavors (n{sub f}=2) of light dynamical quarks. The calculations are performed on the lattice using O(a) improved Wilson fermions and include taking the continuum limit. We find {lambda}{sub n{sub f}=0}{sup MS}=259(1)(19) MeV and {lambda}{sub n{sub f}=2}{sup MS}=261(17)(26) MeV, using r{sub 0}=0.467 fm to set the scale. Extrapolating our results to five flavors, we obtain for the running coupling constant at the mass of the Z boson {alpha}{sub s}{sup MS}(m{sub Z})=0.112(1)(2)

  9. Lattice Formulation of QCD “NEAR the Light CONE”

    NASA Astrophysics Data System (ADS)

    Grünewald, D.

    2007-03-01

    Non-perturbative physics on the light cone is investigated in a Hamiltonian lattice framework. We use near light cone coordinates and perform a limiting procedure onto the light cone. Such a formulation is natural in order to describe high energy scattering. It contains an additional parameter η which represents the distance to the light cone and is varying the energy. The QCD vacuum is planned to be generated by a quantum diffusion Monte Carlo algorithm. In order to minimize the algorithmic variance, a guidance wave functional close to the exact ground state is required. We present a solution for the ground state corresponding to the dominant part of the Hamiltonian in the light cone limit.

  10. New representation of the Adler function for lattice QCD

    NASA Astrophysics Data System (ADS)

    Francis, Anthony; Jäger, Benjamin; Meyer, Harvey B.; Wittig, Hartmut

    2013-09-01

    We address several aspects of lattice QCD calculations of the hadronic vacuum polarization and the associated Adler function. We implement a representation derived previously which allows one to access these phenomenologically important functions for a continuous set of virtualities, irrespective of the flavor structure of the current. Secondly, we present a theoretical analysis of the finite-size effects on our particular representation of the Adler function, based on the operator product expansion at large momenta and on the spectral representation of the Euclidean correlator at small momenta. Finally, an analysis of the flavor structure of the electromagnetic current correlator is performed, where a recent theoretical estimate of the Wick-disconnected diagram contributions is rederived independently and confirmed.

  11. Spin-3/2 baryons in lattice QCD

    SciTech Connect

    J.M. Zanotti; S. Choe; D.B. Leinweber; W. Melnitchouk; A.G. Williams; J.B. Zhang

    2002-06-01

    We present first results for masses of spin-3/2 baryons in lattice QCD, using a novel fat-link clover fermion action in which only the irrelevant operators are constructed using fat links. In the isospin-1/2 sector, we observe, after appropriate spin and parity projection, a strong signal for the J{sup P} = 3/2{sup -} state, and find good agreement between the 1/2{sup +} mass and earlier nucleon mass simulations with a spin-1/2 interpolating field. For the isospin-3/2 Delta states, clear mass splittings are observed between the various 1/2{sup +/-} and the 3/2{sup +/-} channels, with the calculated level orderings in good agreement with those observed empirically.

  12. Hadron-hadron interaction from SU(2) lattice QCD

    SciTech Connect

    Takahashi, Toru T.; Kanada-En'yo, Yoshiko

    2010-11-01

    We evaluate interhadron interactions in two-color lattice QCD from Bethe-Salpeter amplitudes on the Euclidean lattice. The simulations are performed in quenched SU(2) QCD with the plaquette gauge action at {beta}=2.45 and the Wilson quark action. We concentrate on S-wave scattering states of two scalar diquarks. Evaluating different flavor combinations with various quark masses, we try to find out the ingredients in hadronic interactions. Between two scalar diquarks (uC{gamma}{sub 5}d, the lightest baryon in SU(2) system), we observe repulsion in short-range region, even though present quark masses are not very light. We define and evaluate the quark-exchange part in the interaction, which is induced by adding quark-exchange diagrams, or equivalently, by introducing Pauli-blocking among some of quarks. The repulsive force in short-distance region arises only from the quark-exchange part and disappears when quark-exchange diagrams are omitted. We find that the strength of repulsion grows in light quark-mass regime, and its quark-mass dependence is similar to or slightly stronger than that of the color-magnetic interaction by one-gluon-exchange (OGE) processes. It is qualitatively consistent with the constituent-quark-model picture that a color-magnetic interaction among quarks is the origin of repulsion. We also find a universal long-range attractive force, which enters in any flavor channels of two scalar diquarks and whose interaction range and strength are quark-mass independent. The weak quark-mass dependence of interaction ranges in each component implies that meson-exchange contributions are small and subdominant, and the other contributions, e.g., flavor-exchange processes, color-Coulomb, or color-magnetic interactions, are considered to be predominant, in the quark-mass range we evaluated.

  13. Hamiltonian Effective Field Theory Study of the N*(1535 ) Resonance in Lattice QCD

    NASA Astrophysics Data System (ADS)

    Liu, Zhan-Wei; Kamleh, Waseem; Leinweber, Derek B.; Stokes, Finn M.; Thomas, Anthony W.; Wu, Jia-Jun

    2016-02-01

    Drawing on experimental data for baryon resonances, Hamiltonian effective field theory (HEFT) is used to predict the positions of the finite-volume energy levels to be observed in lattice QCD simulations of the lowest-lying JP=1 /2- nucleon excitation. In the initial analysis, the phenomenological parameters of the Hamiltonian model are constrained by experiment and the finite-volume eigenstate energies are a prediction of the model. The agreement between HEFT predictions and lattice QCD results obtained on volumes with spatial lengths of 2 and 3 fm is excellent. These lattice results also admit a more conventional analysis where the low-energy coefficients are constrained by lattice QCD results, enabling a determination of resonance properties from lattice QCD itself. Finally, the role and importance of various components of the Hamiltonian model are examined.

  14. Improved methods for the study of hadronic physics from lattice QCD

    SciTech Connect

    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.

  15. Improved methods for the study of hadronic physics from lattice QCD

    SciTech Connect

    Orginos, Konstantinos; Richards, David G.

    2015-03-01

    The solution of quantum chromodynamics (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 paper, 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.

  16. Dyons near the transition temperature in lattice QCD

    NASA Astrophysics Data System (ADS)

    Bornyakov, V. G.; Ilgenfritz, E.-M.; Martemyanov, B. V.; Müller-Preussker, M.

    2016-04-01

    We study the topological structure of QCD by cluster analysis. The fermionic topological charge density is constructed from low-lying modes of the overlap Dirac operator for three types of temporal boundary conditions for the fermion field. This provides the possibility of marking all three dyon constituents of Kraan-van Baal-Lee-Lu (KvBLL) calorons in the gluonic fields. The gluonic topological charge density appears in the overimproved gradient flow process stopped at the moment when it maximally matches the fermionic topological charge density. This corresponds to the smearing of gluonic fields up to the scale set by dyon size. The timelike Abelian monopoles and specific KvBLL pattern of the Polyakov line are correlated with topological clusters.

  17. Study of decuplet baryon resonances from lattice QCD

    NASA Astrophysics Data System (ADS)

    Alexandrou, C.; Negele, J. W.; Petschlies, M.; Pochinsky, A. V.; Syritsyn, S. N.

    2016-06-01

    A lattice QCD study of the strong decay width and coupling constant of decuplet baryons to an octet baryon-pion state is presented. The transfer matrix method is used to obtain the overlap of lattice states with decuplet baryon quantum numbers on the one hand and octet baryon-pion quantum numbers on the other as an approximation of the matrix element of the corresponding transition. By making use of leading-order effective field theory, the coupling constants as well as the widths for the various decay channels are determined. The transitions studied are Δ →π N , Σ*→Λ π , Σ*→Σ π and Ξ*→Ξ π . We obtain results for two ensembles of Nf=2 +1 dynamical fermion configurations: one using domain wall valence quarks on a staggered sea at a pion mass of 350 MeV and a box size of 3.4 fm and a second one using domain wall sea and valence quarks at pion mass 180 MeV and box size 4.5 fm.

  18. Roper resonance and S11(1535) from lattice QCD

    SciTech Connect

    N. Mathur; Y. Chen; S.J. Dong; T. Draper; I. HorvCith; F.X. Lee; K.F. Liu; J.B. Zhang

    2005-01-06

    Using the constrained curve fitting method and overlap fermions with the lowest pion mass at 180 MeV, we observe that the masses of the first positive and negative parity excited states of the nucleon tend to cross over as the quark masses are taken to the chiral limit. Both results at the physical pion mass agree with the experimental values of the Roper resonance (N{sup 1/2+} (1440)) and S{sub 11} (N{sup 1/2-}(1535)). This is seen for the first time in a lattice QCD calculation. These results are obtained on a quenched Iwasaki 16{sup 3} x 28 lattice with a = 0.2 fm. We also extract the ghost {eta}{prime} N states (a quenched artifact) which are shown to decouple from the nucleon interpolation field above m{sub {pi}} {approx} 300 MeV. From the quark mass dependence of these states in the chiral region, we conclude that spontaneously broken chiral symmetry dictates the dynamics of light quarks in the nucleon.

  19. Neutron Electric Dipole Moment and Tensor Charges from Lattice QCD

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Gupta, Rajan; Lin, Huey-Wen; Yoon, Boram; Pndme Collaboration

    2015-11-01

    We present lattice QCD results on the neutron tensor charges including, for the first time, a simultaneous extrapolation in the lattice spacing, volume, and light quark masses to the physical point in the continuum limit. We find that the "disconnected" contribution is smaller than the statistical error in the "connected" contribution. Our estimates in the modified minimal subtraction scheme at 2 GeV, including all systematics, are gTd -u=1.020 (76 ), gTd=0.774 (66 ), gTu=-0.233 (28 ), and gTs=0.008 (9 ). The flavor diagonal charges determine the size of the neutron electric dipole moment (EDM) induced by quark EDMs that are generated in many new scenarios of C P violation beyond the standard model. We use our results to derive model-independent bounds on the EDMs of light quarks and update the EDM phenomenology in split supersymmetry with gaugino mass unification, finding a stringent upper bound of dn<4 ×1 0-28 e cm for the neutron EDM in this scenario.

  20. Neutron Electric Dipole Moment and Tensor Charges from Lattice QCD.

    PubMed

    Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Gupta, Rajan; Lin, Huey-Wen; Yoon, Boram

    2015-11-20

    We present lattice QCD results on the neutron tensor charges including, for the first time, a simultaneous extrapolation in the lattice spacing, volume, and light quark masses to the physical point in the continuum limit. We find that the "disconnected" contribution is smaller than the statistical error in the "connected" contribution. Our estimates in the modified minimal subtraction scheme at 2 GeV, including all systematics, are g_{T}^{d-u}=1.020(76), g_{T}^{d}=0.774(66), g_{T}^{u}=-0.233(28), and g_{T}^{s}=0.008(9). The flavor diagonal charges determine the size of the neutron electric dipole moment (EDM) induced by quark EDMs that are generated in many new scenarios of CP violation beyond the standard model. We use our results to derive model-independent bounds on the EDMs of light quarks and update the EDM phenomenology in split supersymmetry with gaugino mass unification, finding a stringent upper bound of d_{n}<4×10^{-28} e cm for the neutron EDM in this scenario. PMID:26636847

  1. Nucleon Structure and hyperon form factors from lattice QCD

    SciTech Connect

    Lin, Huey-Wen

    2007-06-11

    In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point to be 1.23(5), consistant with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(26), consistent with the Adelaide-JLab Collaboration's result. The hyperon Sigma and Xi axial coupling constants are also performed for the first time in a lattice calculation, g_SigmaSigma = 0.441(14) and g_XiXi = -0.277(11).

  2. Nucleon Structure and Hyperon Form Factors from Lattice QCD.

    SciTech Connect

    Lin,H.W.

    2007-06-11

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

  3. Matching excluded-volume hadron-resonance gas models and perturbative QCD to lattice calculations

    NASA Astrophysics Data System (ADS)

    Albright, M.; Kapusta, J.; Young, C.

    2014-08-01

    We match three hadronic equations of state at low energy densities to a perturbatively computed equation of state of quarks and gluons at high energy densities. One of them includes all known hadrons treated as point particles, which approximates attractive interactions among hadrons. The other two include, in addition, repulsive interactions in the form of excluded volumes occupied by the hadrons. A switching function is employed to make the crossover transition from one phase to another without introducing a thermodynamic phase transition. A χ2 fit to accurate lattice calculations with temperature 100QCD running gauge coupling and the hard core radius of protons and neutrons, which turns out to be 0.62±0.04 fm. The most physically reasonable models include the excluded-volume effect. Not only do they include the effects of attractive and repulsive interactions among hadrons, but they also achieve better agreement with lattice QCD calculations of the equation of state. The equations of state constructed in this paper do not result in a phase transition, at least not for the temperatures and baryon chemical potentials investigated. It remains to be seen how well these equations of state will represent experimental data on high-energy heavy-ion collisions when implemented in hydrodynamic simulations.

  4. J.J. Sakurai Prize for Theoretical Particle Physics: 40 Years of Lattice QCD

    NASA Astrophysics Data System (ADS)

    Lepage, Peter

    2016-03-01

    Lattice QCD was invented in 1973-74 by Ken Wilson, who passed away in 2013. This talk will describe the evolution of lattice QCD through the past 40 years with particular emphasis on its first years, and on the past decade, when lattice QCD simulations finally came of age. Thanks to theoretical breakthroughs in the late 1990s and early 2000s, lattice QCD simulations now produce the most accurate theoretical calculations in the history of strong-interaction physics. They play an essential role in high-precision experimental studies of physics within and beyond the Standard Model of Particle Physics. The talk will include a non-technical review of the conceptual ideas behind this revolutionary development in (highly) nonlinear quantum physics, together with a survey of its current impact on theoretical and experimental particle physics, and prospects for the future. Work supported by the National Science Foundation.

  5. Improvement of Wilson fermions and twisted mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Wu, Jackson M. S.

    2005-11-01

    In order for Wilson fermions to be a competitive option to use in lattice QCD (LQCD) simulations, the large inherent discretization errors starting at O(a) (a being the lattice spacing) have to be removed. This can be accomplished through the Symanizk improvement program, where improvement terms have to be added to both the action and the operators of interest with coefficients appropriately chosen so that the rate of convergence to the continuum limit is quadratic in a. For this to be applicable to numerical simulations, improvement coefficients have to be determined non-perturbatively. A program for doing so has been pioneered by the Alpha collaboration. In this work, an extension of that program is made to improve all bilinear operators in QCD with two, three, and four flavours of non-degenerate quarks. With even numbers of quark flavours, an alternative approach is afforded by twisted mass LQCD (tmLQCD), where O(a) improvement in physical quantities can be achieved automatically at maximal twist. In this work, the features and utilities of tmLQCD are studied in detail in the framework of chiral perturbation theory (chiPT). By matching onto an effective chiral theory, the phase structure of tmLQCD and the properties of the mesons (pions) in the theory has been investigated. Pionic quantities easy to calculate in numerical simulations and useful for probing the symmetry breaking effects of tmLQCD have been calculated, and conditions under which automatic O(a) improvement holds at maximal twist has been carefully studied. The resulting twisted mass chiPT has also been extended to study the baryons in this work, which has not been done before. This allows one to probe tmLQCD with more quantities, and in particular, quantities that do not involve quark-disconnected diagrams and so are much easier to calculate in numerical simulations. A major part of this dissertation has already appeared in published form. Chapters 3 through 5 are based on Refs. [1--5].

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

    SciTech Connect

    UMEDA, T.; MATSUFURU, H.

    2005-07-25

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

  7. Determination of the chiral condensate from QCD Dirac spectrum on the lattice

    SciTech Connect

    Fukaya, H.; Onogi, T.; Aoki, S.; Chiu, T. W.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Noaki, J.

    2011-04-01

    We calculate the chiral condensate of QCD with 2, 2+1, and 3 flavors of sea quarks. Lattice QCD simulations are performed employing dynamical overlap fermions with up- and down-quark masses covering a range between 3 and 100 MeV. On L{approx}1.8-1.9 fm lattices at a lattice spacing {approx}0.11 fm, we calculate the eigenvalue spectrum of the overlap-Dirac operator. By matching the lattice data with the analytical prediction from chiral perturbation theory at the next-to-leading order, the chiral condensate in the massless limit of up and down quarks is determined.

  8. Dynamical instability of holographic QCD at finite density

    NASA Astrophysics Data System (ADS)

    Chuang, Wu-Yen; Dai, Shou-Huang; Kawamoto, Shoichi; Lin, Feng-Li; Yeh, Chen-Pin

    2011-05-01

    In this paper we study the dynamical instability of Sakai-Sugimoto’s holographic QCD model at finite baryon density. In this model, the baryon density, represented by the smeared instanton on the world volume of the probe D8-D8¯ mesonic brane, sources the world-volume electric field, and through the Chern-Simons term it will induce the instability to form a chiral helical wave at sufficient high density. Our results show that this kind of instability occurs for sufficiently high baryon number densities. The phase diagram of holographic QCD will thus be changed from the one which is based only on thermodynamics.

  9. Dynamical instability of holographic QCD at finite density

    SciTech Connect

    Chuang, Wu-Yen; Dai, Shou-Huang; Kawamoto, Shoichi; Lin, Feng-Li; Yeh, Chen-Pin

    2011-05-15

    In this paper we study the dynamical instability of Sakai-Sugimoto's holographic QCD model at finite baryon density. In this model, the baryon density, represented by the smeared instanton on the world volume of the probe D8-D8 mesonic brane, sources the world-volume electric field, and through the Chern-Simons term it will induce the instability to form a chiral helical wave at sufficient high density. Our results show that this kind of instability occurs for sufficiently high baryon number densities. The phase diagram of holographic QCD will thus be changed from the one which is based only on thermodynamics.

  10. B B interactions with static bottom quarks from lattice QCD

    NASA Astrophysics Data System (ADS)

    Bicudo, Pedro; Cichy, Krzysztof; Peters, Antje; Wagner, Marc

    2016-02-01

    The isospin, spin and parity dependent potential of a pair of B mesons is computed using Wilson twisted mass lattice QCD with two flavors of degenerate dynamical quarks. The B meson is addressed in the static-light approximation, i.e. the b quarks are infinitely heavy. From the results of the B B meson-meson potentials, a simple rule can be deduced stating which isospin, spin and parity combinations correspond to attractive and which to repulsive forces. We provide fits to the ground state potentials in the attractive channels and discuss the potentials in the repulsive and excited channels. The attractive channels are the most important since they can possibly lead to a bound four-quark state, i.e. a b ¯b ¯u d tetraquark. Using these attractive potentials in the Schrödinger equation, we find an indication for such a tetraquark state of two static bottom antiquarks and two light u /d quarks with mass extrapolated down to the physical value.

  11. Transverse Spin Structure of the Nucleon from Lattice-QCD Simulations

    SciTech Connect

    Goeckeler, M.; Schaefer, A.; Haegler, Ph.; Horsley, R.; Zanotti, J. M.; Nakamura, Y.; Pleiter, D.; Schierholz, G.

    2007-06-01

    We present the first calculation in lattice QCD of the lowest two moments of transverse spin densities of quarks in the nucleon. They encode correlations between quark spin and orbital angular momentum. Our dynamical simulations are based on two flavors of clover-improved Wilson fermions and Wilson gluons. We find significant contributions from certain quark helicity flip generalized parton distributions, leading to strongly distorted densities of transversely polarized quarks in the nucleon. In particular, based on our results and recent arguments by Burkardt [Phys. Rev. D 72, 094020 (2005)], we predict that the Boer-Mulders function h{sub 1}{sup perpendicular}, describing correlations of transverse quark spin and intrinsic transverse momentum of quarks, is large and negative for both up and down quarks.

  12. Lattice QCD results for the B --> D(*) l nu form factors: F(1) and G(1)

    SciTech Connect

    Van de Water, R.S.; /Fermilab

    2007-01-01

    I review the current status of lattice QCD calculations of the B {yields} D and B {yields} D* form factors and discuss prospects for their improvement. Successful calculations within the quenched approximation demonstrate the power of lattice methods for calculating F(1) and G(1), and the unquenched calculations in progress should soon allow for a 2-3% exclusive determination of |Vcb|.

  13. QCD thermodynamics from an imaginary {mu}{sub B}: Results on the four flavor lattice model

    SciTech Connect

    D'Elia, Massimo; Lombardo, Maria-Paola

    2004-10-01

    We study four flavor QCD at nonzero temperature and density by analytic continuation from an imaginary chemical potential. The explored region is T=0.95T{sub c}density, the order parameter for chiral symmetry, and the pressure, which is calculated via an integral method at fixed temperature and quark mass. The simulations are carried out on a 16{sup 3}x4 lattice, and the mass dependence of the results is estimated by exploiting the Maxwell relations. In the hadronic region, we confirm that the results are consistent with a simple resonance hadron gas model, and we estimate the critical density by combining the results for the number density with those for the critical line. In the hot phase, above the end point of the Roberge-Weiss transition T{sub E}{approx_equal}1.1T{sub c}, the results are consistent with a free lattice model with a fixed effective number of flavor slightly different from four. We confirm that confinement and chiral symmetry are coincident by a further analysis of the critical line, and we discuss the interrelation between thermodynamics and critical behavior. We comment on the strength and weakness of the method, and propose further developments.

  14. QCD thermodynamics from an imaginary μB: Results on the four flavor lattice model

    NASA Astrophysics Data System (ADS)

    D'Elia, Massimo; Lombardo, Maria-Paola

    2004-10-01

    We study four flavor QCD at nonzero temperature and density by analytic continuation from an imaginary chemical potential. The explored region is T=0.95Tcdensity, the order parameter for chiral symmetry, and the pressure, which is calculated via an integral method at fixed temperature and quark mass. The simulations are carried out on a 163×4 lattice, and the mass dependence of the results is estimated by exploiting the Maxwell relations. In the hadronic region, we confirm that the results are consistent with a simple resonance hadron gas model, and we estimate the critical density by combining the results for the number density with those for the critical line. In the hot phase, above the end point of the Roberge-Weiss transition TE≃1.1Tc, the results are consistent with a free lattice model with a fixed effective number of flavor slightly different from four. We confirm that confinement and chiral symmetry are coincident by a further analysis of the critical line, and we discuss the interrelation between thermodynamics and critical behavior. We comment on the strength and weakness of the method, and propose further developments.

  15. Present constraints on the H-dibaryon at the physical point from Lattice QCD

    SciTech Connect

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

    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 dependence 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.

  16. Exotic and excited-state meson spectroscopy and radiative transitions from lattice QCD

    SciTech Connect

    Christopher Thomas

    2010-09-01

    We discuss recent progress in extracting the excited meson spectrum and radiative transition form factors using lattice QCD. We mention results in the charmonium sector, including the first lattice QCD calculation of radiative transition rates involving excited charmonium states, highlighting results for high spin and exotic states. We present recent results on a highly excited isovector meson spectrum from dynamical anisotropic lattices. Using carefully constructed operators we show how the continuum spin of extracted states can be reliably identified and confidently extract excited states, states with exotic quantum numbers and states of high spin. This spectrum includes the first spin-four state extracted from lattice QCD. We conclude with some comments on future prospects.

  17. Determination of the Chiral Condensate from (2+1)-Flavor Lattice QCD

    SciTech Connect

    Fukaya, H.; Aoki, S.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Noaki, J.; Onogi, T.

    2010-03-26

    We perform a precise calculation of the chiral condensate in QCD using lattice QCD with 2+1 flavors of dynamical overlap quarks. Up and down quark masses cover a range between 3 and 100 MeV on a 16{sup 3}x48 lattice at a lattice spacing {approx}0.11 fm. At the lightest sea quark mass, the finite volume system on the lattice is in the {epsilon} regime. By matching the low-lying eigenvalue spectrum of the Dirac operator with the prediction of chiral perturbation theory at the next-to-leading order, we determine the chiral condensate in (2+1)-flavor QCD with strange quark mass fixed at its physical value as {Sigma}{sup MS}(2 GeV)=[242(04)((+19/-18)) MeV]{sup 3} where the errors are statistical and systematic, respectively.

  18. Present constraints on the H-dibaryon at the physical point from Lattice QCD

    DOE PAGESBeta

    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

  19. Dπ scattering and D meson resonances from lattice QCD

    NASA Astrophysics Data System (ADS)

    Mohler, Daniel; Prelovsek, Sasa; Woloshyn, R. M.

    2013-02-01

    A first exploratory lattice QCD simulation is presented, aimed at extracting the masses and widths of the broad scalar D0*(2400) and the axial D1(2430) charm-light resonances. For that purpose Dπ and D*π scattering are simulated, and the resonance parameters are extracted using a Breit-Wigner fit of the resulting phase shifts. We use a single two-flavor dynamical ensemble with mπ≈266MeV, a≃0.124fm and a rather small volume V=163×32. The resulting D0*(2400) mass is 351±21MeV above the spin average (1)/(4)(mD+3mD*), in agreement with the experimental value of 347±29MeV above. The resulting D0*→Dπ coupling, glat=2.55±0.21GeV, is close to the experimental value gexp⁡≤1.92±0.14GeV, where g parametrizes the width Γ≡g2p*/s. The resonance parameters for the broad D1(2430) are also found close to the experimental values; these are obtained by appealing to the heavy quark limit, where the neighboring resonance D1(2420) is narrow. The calculated I=1/2 scattering lengths are a0=0.81±0.14fm for Dπ and a0=0.81±0.17fm for D*π scattering. The simulation of the scattering in these channels incorporates quark-antiquark as well as multihadron interpolators, and the distillation method is used for contractions. In addition, the ground and several excited charm-light and charmonium states with various JP are calculated using standard quark-antiquark interpolators.

  20. Global QCD Analysis of Polarized Parton Densities

    SciTech Connect

    Stratmann, Marco

    2009-08-04

    We focus on some highlights of a recent, first global Quantum Chromodynamics (QCD) analysis of the helicity parton distributions of the nucleon, mainly the evidence for a rather small gluon polarization over a limited region of momentum fraction and for interesting flavor patterns in the polarized sea. It is examined how the various sets of data obtained in inclusive and semi-inclusive deep inelastic scattering and polarized proton-proton collisions help to constrain different aspects of the quark, antiquark, and gluon helicity distributions. Uncertainty estimates are performed using both the robust Lagrange multiplier technique and the standard Hessian approach.

  1. A Review of Nucleon Spin Calculations in Lattice QCD

    SciTech Connect

    Huey-Wen Lin

    2009-08-01

    We review recent progress on lattice calculations of nucleon spin structure, including the parton distribution functions, form factors, generalization parton distributions, and recent developments in lattice techniques.

  2. The Excited-state Spectrum of QCD through Lattice Gauge Theory Calculations

    SciTech Connect

    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.

  3. Domain decomposition, multilevel integration, and exponential noise reduction in lattice QCD

    NASA Astrophysics Data System (ADS)

    Cè, Marco; Giusti, Leonardo; Schaefer, Stefan

    2016-05-01

    We explore the possibility of computing fermionic correlators on the lattice by combining a domain decomposition with a multilevel integration scheme. The quark propagator is expanded in series of terms with a well-defined hierarchical structure. The higher the order of a term, the (exponentially) smaller its magnitude, the less local is its dependence on the gauge field. Once inserted in a Wick contraction, the gauge-field dependence of the terms in the resulting series can be factorized so that it is suitable for multilevel Monte Carlo integration. We test the strategy in quenched QCD by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and a nucleon two-point function. In either case we observe a significant exponential increase of the signal-to-noise ratio.

  4. Bottom hadrons from lattice QCD with domain wall and NRQCD fermions

    SciTech Connect

    Stefan Meinel, William Detmold, C.-J. David Lin, Matthew Wingate

    2009-07-01

    Dynamical 2+1 flavor lattice QCD is used to calculate the masses of bottom hadrons, including B mesons, singly and doubly bottom baryons, and for the first time also the triply-bottom baryon Omega{sub bbb}. The domain wall action is used for the up-, down-, and strange quarks (both valence and sea), while the bottom quark is implemented with non-relativistic QCD. A calculation of the bottomonium spectrum is also presented.

  5. Comparative Study of Algorithms for the Numerical Simulation of Lattice QCD

    SciTech Connect

    Luz, Fernando H. P.; Mendes, Tereza

    2010-11-12

    Large-scale numerical simulations are the prime method for a nonperturbative study of QCD from first principles. Although the lattice simulation of the pure-gauge (or quenched-QCD) case may be performed very efficiently on parallel machines, there are several additional difficulties in the simulation of the full-QCD case, i.e. when dynamical quark effects are taken into account. We discuss the main aspects of full-QCD simulations, describing the most common algorithms. We present a comparative analysis of performance for two versions of the hybrid Monte Carlo method (the so-called R and RHMC algorithms), as provided in the MILC software package. We consider two degenerate flavors of light quarks in the staggered formulation, having in mind the case of finite-temperature QCD.

  6. LATTICE QCD AT HIGH TEMPERATURE AND THE QGP.

    SciTech Connect

    KARSCH, F.

    2005-10-24

    We review recent progress in studies of bulk thermodynamics of strongly interacting matter, present results on the QCD equation of state and discuss the status of studies of the phase diagram at non-vanishing quark chemical potential.

  7. Estimate of the charmed 0{sup --} hybrid meson spectrum from quenched lattice QCD

    SciTech Connect

    Liu Yan; Luo Xiangqian

    2006-03-01

    We compute from quenched lattice QCD the ground state masses of the charmed hybrid mesons ccg, with exotic quantum numbers J{sup PC}=1{sup -+}, 0{sup +-} and 0{sup --}. The 0{sup --} hybrid meson spectrum has never been provided by lattice simulations due to the difficulties to extract high gluonic excitations from noise. We employ improved gauge and fermion actions on the anisotropic lattice, which reduce greatly the lattice artifacts, and lead to very good signals. The data are extrapolated to the continuum limit, with finite size effects under well control. For 1{sup -+} and 0{sup +-} hybrid mesons, the ground state masses are 4.405(38) GeV and 4.714(52) GeV. We predict for the first time from lattice QCD, the ground state mass of 0{sup --} to be 5.883(146) GeV.

  8. Magnetic structure of light nuclei from lattice QCD

    DOE PAGESBeta

    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

  9. Magnetic structure of light nuclei from lattice QCD

    SciTech Connect

    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

  10. Determination of hadron-quark phase transition line from lattice QCD and two-solar-mass neutron star observations

    NASA Astrophysics Data System (ADS)

    Sugano, Junpei; Kouno, Hiroaki; Yahiro, Masanobu

    2016-07-01

    We aim at drawing the hadron-quark phase transition line in the QCD phase diagram by using the two-phase model (TPM) in which the entanglement Polyakov-loop extended Nambu-Jona-Lasinio (EPNJL) model with the vector-type four-quark interaction is used for the quark phase and the relativistic mean field (RMF) model is used for the hadron phase. A reasonable TPM is constructed by using lattice QCD data and neutron star observations as reliable constraints. For the EPNJL model, we determine the strength of vector-type four-quark interaction at zero quark chemical potential from lattice QCD data on quark number density normalized by its Stefan-Boltzmann limit. For the hadron phase, we consider three RMF models: NL3; TM1; and the model proposed by Maruyama, Tatsumi, Endo, and Chiba (MTEC). We find that MTEC is most consistent with the neutron star observations and TM1 is the second best. Assuming that the hadron-quark phase transition occurs in the core of a neutron star, we explore the density dependence of vector-type four-quark interaction. Particularly for the critical baryon chemical potential μBc at zero temperature, we determine a range of μBc for the quark phase to occur in the core of a neutron star. The values of μBc lie in the range 1560 MeV ≤μBc≤1910 MeV .

  11. Nucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry

    SciTech Connect

    Ohki, H.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Matsufuru, H.; Noaki, J.; Shintani, E.; Onogi, T.

    2008-09-01

    We calculate the nucleon sigma term in two-flavor lattice QCD utilizing the Feynman-Hellman theorem. Both sea and valence quarks are described by the overlap fermion formulation, which preserves exact chiral and flavor symmetries on the lattice. We analyze the lattice data for the nucleon mass using the analytical formulae derived from the baryon chiral perturbation theory. From the data at valence quark mass set different from sea quark mass, we may extract the sea quark contribution to the sigma term, which corresponds to the strange quark content. We find that the strange quark content is much smaller than the previous lattice calculations and phenomenological estimates.

  12. Magnetic structure of light nuclei from lattice QCD

    NASA Astrophysics Data System (ADS)

    Chang, Emmanuel; Detmold, William; Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; Beane, Silas R.; Nplqcd Collaboration

    2015-12-01

    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 ≤4 , along with the cross section for the M 1 transition n p →d γ , at the flavor SU(3)-symmetric point where the pion mass is mπ˜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 article [S. Beane et al., Phys. Rev. Lett. 113, 252001 (2014)]. For the charged states, the extraction of the polarizability requires careful treatment of Landau levels, which enter nontrivially in the method that is employed. The nucleon polarizabilities are found to be of similar magnitude to their physical values, with βp=5.22 (+0.66/-0.45) (0.23 )×10-4 fm3 and βn=1.253 (+0.056/-0.067) (0.055 )×10-4 fm3 , exhibiting a significant isovector component. The dineutron is bound at these heavy quark masses, and its magnetic polarizability, βn n=1.872 (+0.121/-0.113) (0.082 )×10-4 fm3 , differs significantly from twice that of the neutron. A linear combination of deuteron scalar and tensor polarizabilities is determined by the energies of the jz=±1 deuteron states and is found to be βd ,±1=4.4 (+1.6/-1.5) (0.2 )×10-4 fm3 . 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, β3He =5.4 (+2.2/-2.1) (0.2 )×10-4 fm3 , β​3H=2.6 (1.7 )(0.1 )×10-4 fm3 , and β4He=3.4 (+2.0/-1.9) (0.2 )×10-4 fm3 . Mixing between the jz=0 deuteron state and the spin-singlet n p state induced by the background magnetic field is used to extract the short-distance two-nucleon counterterm, L¯1, of the pionless effective theory for N N systems (equivalent to the meson-exchange current contribution in nuclear potential models) that dictates the cross section for the n p →d γ process near threshold. Combined with

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

    SciTech Connect

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

    2015-01-15

    Recently experimentalists have discovered several charged charmoniumlike hadrons Zc+ with unconventional quark content c¯cd¯u. We perform a search for Zc+ with mass below 4.2 GeV in the channel IG(JPC)=1+(1+-) using lattice QCD. The major challenge is presented by the two-meson states J/ψπ, ψ2Sπ, ψ1D

  14. Better than $l/Mflops sustained: a scalable PC-based parallel computer for lattice QCD

    NASA Astrophysics Data System (ADS)

    Fodor, Zoltán; Katz, Sándor D.; Papp, Gábor

    2003-05-01

    We study the feasibility of a PC-based parallel computer for medium to large scale lattice QCD simulations. The Eötvös Univ., Inst. Theor. Phys. cluster consists of 137 Intel P4-1.7GHz nodes with 512 MB RDRAM. The 32-bit, single precision sustained performance for dynamical QCD without communication is 1510 Mflops/node with Wilson and 970 Mflops/node with staggered fermions. This gives a total performance of 208 Gflops for Wilson and 133 Gflops for staggered QCD, respectively (for 64-bit applications the performance is approximately halved). The novel feature of our system is its communication architecture. In order to have a scalable, cost-effective machine we use Gigabit Ethernet cards for nearest-neighbor communications in a two-dimensional mesh. This type of communication is cost effective (only 30% of the hardware costs is spent on the communication). According to our benchmark measurements this type of communication results in around 40% communication time fraction for lattices upto 48 3·96 in full QCD simulations. The price/sustained-performance ratio for full QCD is better than l/Mflops for Wilson (and around 1.5/Mflops for staggered) quarks for practically any lattice size, which can fit in our parallel computer. The communication software is freely available upon request for non-profit organizations.

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

    SciTech Connect

    Bernard, C.; DeTar, Carleton; Levkova, L.; Di Pierro, Massimo; El-Khadra, Aida Xenia; Evans, R.T.; Jain, R.; Freeland, Elizabeth Dawn; Gottlieb, Steven A.; Heller, Urs M.; Hetrick, James E.; /U. Pacific, Stockton /Fermilab /Simon Fraser U. /Arizona U. /UC, Santa Barbara

    2006-01-01

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

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

    SciTech Connect

    Kronfeld, Andreas S.; /Fermilab

    2012-03-01

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

  17. Nuclear Physics from Lattice QCD: The Spectrum, Structure and Interactions of Hadrons

    SciTech Connect

    David Richards; Colin Morningstar; John Negele; Konstantinos Orginos; Martin Savage

    2007-02-09

    The importance of lattice QCD to our understanding of the structure, spectroscopy, and interaction of hadrons is decribed. Recent accomplishments in each of these areas is outlined, and the opportunities emerging with increasing computational power are identified. Milestones at the 10 Tflops-years, 100 Tflops-years and Petaflops-years scales are presented.

  18. Effects of LatticeQCD EoS and Continuous Emission on Some Observables

    SciTech Connect

    Hama, Y.; Andrade, R.; Grassi, F.; Socolowski, O.; Kodama, T.; Tavares, B.; Padula, S. S.

    2006-04-11

    Effects of lattice-QCD-inspired equations of state and continuous emission on some observables are discussed, by solving a 3D hydrodynamics. The particle multiplicity as well {nu} 2 are found to increase in the mid-rapidity. We also discuss the effects of the initial-condition fluctuations.

  19. Simple QED- and QCD-like models at finite density

    NASA Astrophysics Data System (ADS)

    Pawlowski, Jan M.; Stamatescu, Ion-Olimpiu; Zielinski, Christian

    2015-07-01

    In this paper we discuss one-dimensional models reproducing some features of quantum electrodynamics and quantum chromodynamics at nonzero density and temperature. Since a severe sign problem makes a numerical treatment of QED and QCD at high density difficult, such models help to explore various effects peculiar to the full theory. Studying them gives insights into the large density behavior of the Polyakov loop by taking both bosonic and fermionic degrees of freedom into account, although in one dimension only the implementation of a global gauge symmetry is possible. For these models we evaluate the respective partition functions and discuss several observables as well as the Silver Blaze phenomenon.

  20. Thermodynamics of lattice QCD with 2 light dynamical (staggered) quark flavours on a 16{sup 3} {times} 8 lattice

    SciTech Connect

    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.

  1. Thermodynamics of lattice QCD with 2 light dynamical (staggered) quark flavours on a 16 sup 3 times 8 lattice

    SciTech Connect

    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.

  2. The nucleon axial charge in full lattice QCD

    SciTech Connect

    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.

  3. Axial couplings of heavy hadrons from domain-wall lattice QCD

    SciTech Connect

    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.

  4. Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs)

    NASA Astrophysics Data System (ADS)

    Engelhardt, M.; Musch, B.; Bhattacharya, T.; Green, J. R.; Gupta, R.; Hägler, P.; Krieg, S.; Negele, J.; Pochinsky, A.; Schäfer, A.; Syritsyn, S.; Yoon, B.

    2016-03-01

    An ongoing program of evaluating TMD observables within Lattice QCD is reviewed, summarizing recent progress with respect to several challenges faced by such calculations. These lattice calculations are based on a definition of TMDs through hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for a lattice calculation. Data on the naively T-odd Sivers and Boer-Mulders effects as well as the transversity TMD are presented.

  5. Massive photons: An infrared regularization scheme for lattice QCD+QED

    DOE PAGESBeta

    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

  6. Bottomonium spectrum from lattice QCD with 2+1 flavors of domain wall fermions

    SciTech Connect

    Meinel, Stefan

    2009-05-01

    Recently, realistic lattice QCD calculations with 2+1 flavors of domain wall fermions and the Iwasaki gauge action have been performed by the RBC and UKQCD Collaborations. Here, results for the bottomonium spectrum computed on their gauge configurations of size 24{sup 3}x64 with a lattice spacing of approximately 0.11 fm and four different values for the light quark mass are presented. Improved lattice nonrelativistic QCD is used to treat the b quarks inside the bottomonium. The results for the radial and orbital energy splittings are found to be in good agreement with experimental measurements, indicating that systematic errors are small. The calculation of the {upsilon}(2S)-{upsilon}(1S) energy splitting provides an independent determination of the lattice spacing. For the most physical ensemble it is found to be a{sup -1}=1.740(25)(19) GeV, where the first error is statistical/fitting and the second error is an estimate of the systematic errors due to the lattice nonrelativistic QCD action.

  7. Thermodynamics of (2+1)-flavor QCD: Confronting models with lattice studies

    SciTech Connect

    Schaefer, B.-J.; Wagner, M.; Wambach, J.

    2010-04-01

    The Polyakov-quark-meson model, which combines chiral as well as deconfinement aspects of strongly interacting matter, is introduced for three light quark flavors. An analysis of the chiral and deconfinement phase transition of the model and its thermodynamics at finite temperatures is given. Three different forms of the effective Polyakov-loop potential are considered. The findings of the 2+1 flavor model investigations are compared to corresponding recent QCD lattice simulations of the RBC-Bielefeld, HotQCD and Wuppertal-Budapest collaborations. The influence of the heavier quark masses, which are used in the lattice calculations, is taken into account. In the transition region the bulk thermodynamics of the Polyakov-quark-meson model agrees well with the lattice data.

  8. How to measure epsilon'/epsilon with lattice QCD

    SciTech Connect

    Sharpe, S.R.

    1987-04-01

    A pedagogical discussion is given of a lattice calculation of epsilon'. The method is outlined, and preliminary results are presented. They suggest that epsilon'/epsilon may be reduced from previous estimates by 60-70%.

  9. ϒ and ϒ' leptonic widths, aμb , and mb from full lattice QCD

    NASA Astrophysics Data System (ADS)

    Colquhoun, B.; Dowdall, R. J.; Davies, C. T. H.; Hornbostel, K.; Lepage, G. P.; Hpqcd Collaboration

    2015-04-01

    We determine the decay rate to leptons of the ground-state ϒ meson and its first radial excitation in lattice QCD for the first time. We use radiatively improved nonrelativistic QCD for the b quarks and include u , d , s and c quarks in the sea with u /d masses down to their physical values. We find Γ (ϒ →e+e-)=1.19 (11 ) keV and Γ (ϒ'→e+e-)=0.69 (9 ) keV , both in good agreement with experimental results. The decay constants we obtain are included in a summary plot of meson decay constants from lattice QCD given in the Conclusions. We also test time moments of the vector current-current correlator against values determined from the b -quark contribution to σ (e+e-→hadrons) and calculate the b -quark piece of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, aμb=0.271 (37 )×1 0-10 . Finally we determine the b -quark mass, obtaining in the MS ¯ scheme, m¯ b(m¯ b,nf=5 )=4.196 (23 ) GeV , the most accurate result from lattice QCD to date.

  10. The chiral phase transition for lattice QCD with 2 color-sextet quarks

    NASA Astrophysics Data System (ADS)

    Kogut, J. B.; Sinclair, D. K.

    2015-09-01

    QCD with 2 flavors of massless color-sextet quarks is studied as a possible walking-Technicolor candidate. We simulate the lattice version of this model at finite temperatures near to the chiral-symmetry restoration transition, to determine whether it is indeed a walking theory (QCD-like with a running coupling which evolves slowly over an appreciable range of length scales) or if it has an infrared fixed point, making it a conformal field theory. The lattice spacing at this transition is decreased towards zero by increasing the number Nt of lattice sites in the temporal direction. Our simulations are performed at Nt=4 ,6 ,8 ,12 , on lattices with spatial extent much larger than the temporal extent. A range of small fermion masses is chosen to make predictions for the chiral (zero mass) limit. We find that the bare lattice coupling does decrease as the lattice spacing is decreased. However, it decreases more slowly than would be predicted by asymptotic freedom. We discuss whether this means that the coupling is approaching a finite value as lattice Nt is increased—the conformal option, or if the apparent disagreement with the scaling predicted by asymptotic freedom is because the lattice coupling is a poor expansion parameter, and the theory walks. Currently, evidence favors QCD with 2 color-sextet quarks being a conformal field theory. Other potential sources of disagreement with the walking hypothesis are also discussed. We also report an estimate of the position of the deconfinement transition for Nt=12 , needed for choosing parameters for zero-temperature simulations.

  11. The IR sector of QCD: lattice versus Schwinger-Dyson equations

    SciTech Connect

    Binosi, Daniele

    2010-12-22

    Important information about the infrared dynamics of QCD is encoded in the behavior of its (of-shell) Green's functions, most notably the gluon and the ghost propagators. Due to recent improvements in the quality of lattice data and the truncation schemes employed for the Schwinger-Dyson equations we have now reached a point where the interplay between these two non-perturbative tools can be most fruitful. In this talk several of the above points will be reviewed, with particular emphasis on the implications for the ghost sector, the non-perturbative effective charge of QCD, and the Kugo-Ojima function.

  12. Light composite scalar in twelve-flavor QCD on the lattice.

    PubMed

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

    2013-10-18

    On the basis of lattice simulations using highly improved staggered quarks for twelve-flavor QCD with several bare fermion masses, we observe a flavor-singlet scalar state lighter than the pion in the correlators of fermionic interpolating operators. The same state is also investigated using correlators of gluonic interpolating operators. Combined with our previous study that showed twelve-flavor QCD to be consistent with being in the conformal window, we infer that the lightness of the scalar state is due to infrared conformality. This result shed some light on the possibility of a light composite Higgs boson ("technidilaton") in walking technicolor theories. PMID:24182255

  13. Chiral phase transition in lattice QCD as a metal-insulator transition

    SciTech Connect

    Garcia-Garcia, Antonio M.; Osborn, James C.

    2007-02-01

    We investigate the lattice QCD Dirac operator with staggered fermions at temperatures around the chiral phase transition. We present evidence of a metal-insulator transition in the low lying modes of the Dirac operator around the same temperature as the chiral phase transition. This strongly suggests the phenomenon of Anderson localization drives the QCD vacuum to the chirally symmetric phase in a way similar to a metal-insulator transition in a disordered conductor. We also discuss how Anderson localization affects the usual phenomenological treatment of phase transitions a la Ginzburg-Landau.

  14. Dirac and Pauli form factors from lattice QCD

    SciTech Connect

    Collins, S.; Goeckeler, M.; Nobile, A.; Schaefer, A.; Haegler, Ph.; Horsley, R.; Winter, F.; Zanotti, J. M.; Nakamura, Y.; Pleiter, D.; Rakow, P. E. L.; Schierholz, G.; Schroers, W.; Stueben, H.

    2011-10-01

    We present a comprehensive analysis of the electromagnetic form factors of the nucleon from a lattice simulation with two flavors of dynamical O(a)-improved Wilson fermions. A key feature of our calculation is that we make use of an extensive ensemble of lattice gauge field configurations with four different lattice spacings, multiple volumes, and pion masses down to m{sub {pi}{approx}1}80 MeV. We find that by employing Kelly-inspired parametrizations for the Q{sup 2} dependence of the form factors, we are able to obtain stable fits over our complete ensemble. Dirac and Pauli radii and the anomalous magnetic moments of the nucleon are extracted and results at light quark masses provide evidence for chiral nonanalytic behavior in these fundamental observables.

  15. Extracting the {Omega}{sup -} electric quadrupole moment from lattice QCD data

    SciTech Connect

    Ramalho, G.; Pena, M. T.

    2011-03-01

    The {Omega}{sup -} has an extremely long lifetime, and is the most stable of the baryons with spin 3/2. Therefore the {Omega}{sup -} magnetic moment is very accurately known. Nevertheless, its electric quadrupole moment was never measured, although estimates exist in different formalisms. In principle, lattice QCD simulations provide at present the most appropriate way to estimate the {Omega}{sup -} form factors, as function of the square of the transferred four-momentum, Q{sup 2}, since it describes baryon systems at the physical mass for the strange quark. However, lattice QCD form factors, and in particular G{sub E2}, are determined at finite Q{sup 2} only, and the extraction of the electric quadrupole moment, Q{sub {Omega}}{sup -}=G{sub E2}(0)(e/2M{sub {Omega}}), involves an extrapolation of the numerical lattice results. In this work, we reproduce the lattice QCD data with a covariant spectator quark model for {Omega}{sup -} which includes a mixture of S and two D states for the relative quark-diquark motion. Once the model is calibrated, it is used to determine Q{sub {Omega}}{sup -}. Our prediction is Q{sub {Omega}}{sup -}=(0.96{+-}0.02)x10{sup -2} efm{sup 2}[G{sub E2}(0)=0.680{+-}0.012].

  16. Massive Photons: An Infrared Regularization Scheme for Lattice QCD +QED

    NASA Astrophysics Data System (ADS)

    Endres, Michael G.; Shindler, Andrea; Tiburzi, Brian C.; Walker-Loud, André

    2016-08-01

    Standard methods for including electromagnetic interactions in lattice quantum chromodynamics calculations result in power-law finite-volume corrections to physical quantities. Removing these by extrapolation requires costly computations at multiple volumes. We introduce a photon mass to alternatively regulate the infrared, and rely on effective field theory to remove its unphysical effects. Electromagnetic modifications to the hadron spectrum are reliably estimated with a precision and cost comparable to conventional approaches that utilize multiple larger volumes. A significant overall cost advantage emerges when accounting for ensemble generation. The proposed method may benefit lattice calculations involving multiple charged hadrons, as well as quantum many-body computations with long-range Coulomb interactions.

  17. Two-flavor lattice QCD in the {epsilon} regime and chiral random matrix theory

    SciTech Connect

    Fukaya, H.; Aoki, S.; Chiu, T. W.; Ogawa, K.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Matsufuru, H.; Noaki, J.; Onogi, T.

    2007-09-01

    The low-lying eigenvalue spectrum of the QCD Dirac operator in the {epsilon} regime is expected to match with that of chiral random matrix theory (ChRMT). We study this correspondence for the case including sea quarks by performing two-flavor QCD simulations on the lattice. Using the overlap fermion formulation, which preserves exact chiral symmetry at finite lattice spacings, we push the sea quark mass down to {approx}3 MeV on a 16{sup 3}x32 lattice at a lattice spacing a{approx_equal}0.11 fm. We compare the low-lying eigenvalue distributions and find a good agreement with the analytical predictions of ChRMT. By matching the lowest-lying eigenvalue we extract the chiral condensate, {sigma}{sup MS}(2 GeV)=(251{+-}7{+-}11 MeV){sup 3}, where errors represent statistical and higher order effects in the {epsilon} expansion. We also calculate the eigenvalue distributions on the lattices with heavier sea quarks at two lattice spacings. Although the {epsilon} expansion is not applied for those sea quarks, we find a reasonable agreement of the Dirac operator spectrum with ChRMT. The value of {sigma}, after extrapolating to the chiral limit, is consistent with the estimate in the {epsilon} regime.

  18. More Efficient Thermalization of Gauge Fields in Lattice QCD Simulations

    SciTech Connect

    Frigori, R.B.; Cucchieri, A.; Mendes, T.; Mihara, A.

    2004-12-02

    We introduce a new thermalization algorithm for pure SU(2) lattice gauge theory by combining heat-bath and micro-canonical updates in a single step, while preserving ergodicity. We test the new algorithm in the two-dimensional case and compare its performance with the standard heat-bath method.

  19. Positive-parity excited states of the nucleon in quenched lattice QCD

    SciTech Connect

    Mahbub, M. S.; Cais, Alan O.; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.

    2010-11-01

    Positive-parity spin-(1/2) excitations of the nucleon are explored in lattice QCD. The variational method is used in this investigation and several correlation matrices are employed. As our focus is on the utility and methodology of the variational approach, we work in the quenched approximation to QCD. Various sweeps of Gaussian fermion-field smearing are applied at the source and at the sink of {chi}{sub 1{chi}1} and {chi}{sub 1{chi}2} correlation functions to obtain a large basis of operators. Using several different approaches for constructing basis interpolators, we demonstrate how improving the basis can split what otherwise might be interpreted as a single state into multiple eigenstates. Consistency of the extracted excited energy states are explored over various dimensions of the correlation matrices. The use of large correlation matrices is emphasized for the reliable extraction of the excited eigenstates of QCD.

  20. Flavor symmetry breaking in lattice QCD with a mixed action

    SciTech Connect

    Baer, Oliver; Golterman, Maarten; Shamir, Yigal

    2011-03-01

    We study the phase structure of mixed-action QCD with two Wilson sea quarks and any number of chiral valence quarks (and ghosts), starting from the chiral Lagrangian. A priori the effective theory allows for a rich phase structure, including a phase with a condensate made of sea and valence quarks. In such a phase, mass eigenstates would become admixtures of sea and valence fields, and pure-sea correlation functions would depend on the parameters of the valence sector, in contradiction with the actual setup of mixed-action simulations. Using that the spectrum of the chiral Dirac operator has a gap for nonzero quark mass we prove that spontaneous symmetry breaking of the flavor symmetries can only occur within the sea sector. This rules out a mixed condensate and implies restrictions on the low-energy constants of the effective theory.

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

    SciTech Connect

    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.

  2. The phase-shift of isospin-2 pi-pi scattering from lattice QCD

    SciTech Connect

    Jozef J. Dudek, Robert G. Edwards, Michael J. Peardon, David G. Richards, Christopher E. Thomas

    2011-04-01

    Finite-volume lattice QCD calculations offer the possibility of extracting resonance parameters from the energy-dependent elastic phase-shift computed using the L\\"uscher technique. In this letter, as a trial of the method, we report on the extraction of the non-resonant phase-shift for $S$ and $D$-wave $\\pi\\pi$ isospin-2 scattering from dynamical lattice QCD computations. We define a variational basis of operators resembling pairs of pions of definite relative momentum and extract a spectrum of excited states that maps to phase-shifts at a set of discrete scattering momenta. Computations are performed with pion masses between $400$ and $520$ MeV on multiple spatial volumes. We observe no significant quark mass dependence in the phase-shifts extracted which are in reasonable agreement with the available experimental data at low momentum.

  3. Phase shift of isospin-2 {pi}{pi} scattering from lattice QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.; Richards, David G.; Thomas, Christopher E.; Peardon, Michael J.

    2011-04-01

    Finite-volume lattice QCD calculations offer the possibility of extracting resonance parameters from the energy-dependent elastic phase-shift computed using the Luescher technique. In this letter, as a trial of the method, we report on the extraction of the nonresonant phase-shift for S and D-wave {pi}{pi} isospin-2 scattering from dynamical lattice QCD computations. We define a variational basis of operators resembling pairs of pions of definite relative momentum and extract a spectrum of excited states that maps to phase-shifts at a set of discrete scattering momenta. Computations are performed with pion masses between 400 and 520 MeV on multiple spatial volumes. We observe no significant quark mass dependence in the phase-shifts extracted which are in reasonable agreement with the available experimental data at low momentum.

  4. Status of B[sub K] from lattice QCD

    SciTech Connect

    Gupta, R.

    2002-01-01

    A brief review of lattice calculations of the bag parameter BK relevant for understanding indirect CP violation in the neutral kaon sector is given. A status report on current state-of-the-art calculations is presented as well as a discussion of the value of BK exported to phenomenologists. This review was presented at the CKM Unitarity Triangle Workshop held at CERN during Feburary 13-16, 2002.

  5. Highly excited and exotic meson spectrum from dynamical lattice QCD

    SciTech Connect

    Jozef Dudek, Robert Edwards, David Richards, Christopher Thomas

    2009-12-01

    Using a new quark-field construction algorithm and a large variational basis of operators, we extract a highly excited isovector meson spectrum on dynamical anisotropic lattices. We show how carefully constructed operators can be used to identify the continuum spin of extracted states. This method allows us to extract, with confidence, excited states, states of high spin and states with exotic quantum numbers, including, for the first time, spin-four states.

  6. PRELIMINARY RESULTS FROM A SIMULATION OF QUENCHED QCD WITH OVERL AP FERMIONS ON A LARGE LATTICE.

    SciTech Connect

    BERRUTO,F.GARRON,N.HOELBLING,D.LELLOUCH,L.REBBI,C.SHORESH,N.

    2003-07-15

    We simulate quenched QCD with the overlap Dirac operator. We work with the Wilson gauge action at {beta} = 6 on an 18{sup 3} x 64 lattice. We calculate quark propagators for a single source point and quark mass ranging from am{sub 4} = 0.03 to 0.75. We present here preliminary results based on the propagators for 60 gauge field configurations.

  7. Decay Constants of B and D Mesons from Non-pertubatively Improved Lattice QCD

    SciTech Connect

    K.C. Bowler; L. Del Debbio; J.M. Flynn; G.N, Lacagnina; V.I. Lesk; C.M. Maynard; D.G. Richards

    2000-07-01

    The decay constants of B and D mesons are computed in quenched lattice QCD at two different values of the coupling. The action and operators are ? (a) improved with non-perturbative coefficients where available. The results and systematic errors are discussed in detail. Results for vector decay constants, flavour symmetry breaking ratios of decay constants, the pseudoscalar-vector mass splitting and D meson masses are also presented.

  8. Insights into the Quark-Gluon Vertex from Lattice QCD and Meson Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.; Paracha, M. Ali.

    2015-09-01

    By comparing successful quark-gluon vertex interaction models with the corresponding interaction extracted from lattice-QCD data on the quark's propagator, we identify common qualitative features which could be important to tune future interaction models beyond the rainbow ladder approximation. Clearly, a quantitative comparison is conceptually not simple, but qualitatively the results suggest that a realistic interaction should be relatively broad with a strong support at about 0.4-0.6 GeV and infrared-finite.

  9. Thermodynamics of lattice QCD with 2 quark flavours : chiral symmetry and topology.

    SciTech Connect

    Lagae, J.-F.

    1998-06-09

    We have studied the restoration of chiral symmetry in lattice QCD at the finite temperature transition from hadronic matter to a quark-gluon plasma. By measuring the screening masses of flavour singlet and non-singlet meson excitations, we have seen evidence that, although flavour chiral symmetry is restored at this transition, flavour singlet (U(1)) axial symmetry is not. We conclude that this indicates that instantons continue to play an important role in the quark-gluon plasma phase.

  10. Lattice QCD simulations on big cats, sea monsters and clock towers

    NASA Astrophysics Data System (ADS)

    Joó, Bálint; USQCD Collaboration; Hadron Spectrum Collaboration

    2009-07-01

    We present details of lattice QCD computations we are performing on the Cray XT series of computers, from BigBen - an XT3 hosted at the Pittsburgh Supercomputing Center (PSC) - through Jaguar (XT4) and Kraken (XT5) - which are hosted at the National Center for Computational Science (NCCS) and the National Institute of Computational Science (NICS), respectively, at Oak Ridge National Laboratory (ORNL). We discuss algorithmic tuning to make the computation more efficient and present some recent results.

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

    SciTech Connect

    Bernard, C.; DeTar, C.; Di Pierro, M.; El-Khadra, A.X.; Evans, R.T.; Freeland, E.; Gamiz, E.; Gottlieb, Steven; Heller, U.M.; Hetrick, J.E.; Jain, R.; /Illinois U., Urbana /Fermilab /Fermilab /Washington U., St. Louis

    2007-01-01

    We present new preliminary results for the leptonic decay constants f{sub B} and f{sub D+} determined in 2+1 flavor lattice QCD at lattice spacings a = 0.09, 0.12 and 0.15 fm. Results are obtained using the MILC Collaboration gauge configuration ensembles, clover heavy quarks in the Fermilab interpretation and improved staggered light quarks. Decay constants, computed at partially quenched combinations of the valence and sea light quark masses, are used to determine the low-energy parameters of staggered chiral perturbation theory. The physical decay constants are found in an extrapolation using the parameterized chiral formula.

  12. D K scattering and the D$_s$ spectrum from lattice QCD

    SciTech Connect

    Mohler, Daniel; Lang, C. B.; Leskovec, Luka; Prelovsek, Sasa; Woloshyn, R. M.

    2013-01-01

    We present results from Lattice QCD calculations of the low-lying charmed-strange meson spectrum using two types of Clover-Wilson lattices. In addition to quark-antiquark interpolating fields we also consider meson-meson interpolators corresponding to D-meson kaon scattering states. To calculate the all-to-all propagation necessary for the backtracking loops we use the (stochastic) distillation technique. For the charm quark we use the Fermilab method. Results for the $J^P=0^+$ $D_{s0}^*(2317)$ charmed-strange meson are presented.

  13. Mass of the B(c) meson in three-flavor lattice QCD

    SciTech Connect

    Allison, Ian F.; Davies, Christine T.H.; Gray, Alan; Kronfeld, Andreas S.; Mackenzie, Paul B.; Simone, James N.; /Fermilab

    2004-11-01

    The authors use lattice QCD to predict the mass of the B{sub c} meson. They use the MILC Collaborations publicly available ensembles of lattice gauge fields, which have a quark sea with two flavors (up and down) much lighter than a third (strange). The final result is m{sub B{sub c}} = 6304 {+-} 12{sub -0}{sup +18} MeV. The first error bar is a sum in quadrature of statistical and systematic uncertainties, and the second is an estimate of heavy-quark discretization effects.

  14. Leading-order hadronic contribution to g-2 from lattice QCD

    SciTech Connect

    Dru Renner, Xu Feng, Karl Jansen, Marcus Petschlies

    2011-03-01

    We calculate the leading-order hadronic correction to the anomalous magnetic moments of each of the three charged leptons in the Standard Model: the electron, muon and tau. Working in two-flavor lattice QCD, we address essentially all sources of systematic error: lattice artifacts, finite-size effects, quark-mass extrapolation, momentum extrapolation and disconnected diagrams. The only remaining significant systematic error, the exclusion of the strange and charm quark contributions, will be addressed in our four-flavor calculation. We achieve a statistical accuracy of 2% or better for the physical values for each of the three leptons and the systematic errors are at most comparable.

  15. Neutron and proton electric dipole moments from Nf=2 +1 domain-wall fermion lattice QCD

    NASA Astrophysics Data System (ADS)

    Shintani, Eigo; Blum, Thomas; Izubuchi, Taku; Soni, Amarjit; Rbc; Ukqcd Collaborations

    2016-05-01

    We present a lattice calculation of the neutron and proton electric dipole moments (EDMs) with Nf=2 +1 flavors of domain-wall fermions. The neutron and proton EDM form factors are extracted from three-point functions at the next-to-leading order in the θ vacuum of QCD. In this computation, we use pion masses of 0.33 and 0.42 GeV and 2.7 fm3 lattices with Iwasaki gauge action, and a 0.17 GeV pion and a 4.6 fm3 lattice with I-DSDR gauge action, all generated by the RBC and UKQCD collaborations. The all-mode averaging technique enables an efficient and high statistics calculation. Chiral behavior of lattice EDMs is discussed in the context of baryon chiral perturbation theory. In addition, we also show numerical evidence on the relationship of three- and two-point correlation functions with the local topological charge distribution.

  16. The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD

    DOE PAGESBeta

    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

  17. Static potential and local color fields in unquenched lattice QCD{sub 3}

    SciTech Connect

    Trottier, Howard D.; Wong, Kit Yan

    2005-09-01

    String breaking by dynamical quarks in three-dimensional lattice QCD is analyzed through measurements of the potential and the local color-electric field strength generated by a static quark-antiquark pair. Simulations were done for unquenched SU(2) color with two flavors of staggered light quarks. An improved gluon action was used, which allows simulations to be done on coarse lattices, providing an extremely efficient means to access the large quark separations and long propagation times at which string breaking occurs. The static sources were generated using Wilson loop operators, hence no light valence quarks are present in the resulting trial states. Results give unambiguous evidence of string breaking. First the static potential is shown to saturate at twice the heavy-light meson mass at large separations. Then it is demonstrated that the local color-electric field strength in the region between the heavy quarks tends towards vacuum values at large separations, the first time that this most graphic effect of quark vacuum polarization on the confining flux-tube has been realized in lattice QCD. Implications of these results for unquenched simulations of four-dimensional QCD are drawn.

  18. $$B\\to Kl^+l^-$$ decay form factors from three-flavor lattice QCD

    DOE PAGESBeta

    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

  19. B →K l+l- decay form factors from three-flavor lattice QCD

    NASA Astrophysics Data System (ADS)

    Bailey, Jon A.; Bazavov, A.; Bernard, C.; Bouchard, C. M.; DeTar, C.; Du, Daping; El-Khadra, A. X.; Foley, J.; Freeland, E. D.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Jain, R. D.; Komijani, J.; Kronfeld, A. S.; Laiho, J.; Levkova, L.; Liu, Yuzhi; Mackenzie, P. B.; Meurice, Y.; Neil, E. T.; Qiu, Si-Wei; Simone, J. N.; Sugar, R.; Toussaint, D.; Van de Water, R. S.; Zhou, Ran; Fermilab Lattice; MILC Collaborations

    2016-01-01

    We compute the form factors for the B →K l+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 comprehensive 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. We use this complete description of the form factors to test QCD predictions of the form factors at high and low q2.

  20. Infrared features of unquenched finite temperature lattice Landau gauge QCD

    SciTech Connect

    Furui, Sadataka; Nakajima, Hideo

    2007-09-01

    The color diagonal and color antisymmetric ghost propagators slightly above T{sub c} of N{sub f}=2 MILC 24{sup 3}x12 lattices are measured and compared with zero-temperature unquenched N{sub f}=2+1 MILC{sub c} 20{sup 3}x64 and MILC{sub f} 28{sup 3}x96 lattices and zero-temperature quenched 56{sup 4} {beta}=6.4 and 6.45 lattices. The expectation value of the color antisymmetric ghost propagator {phi}{sup c}(q) is zero, but its Binder cumulant, which is consistent with that of N{sub c}{sup 2}-1 dimensional Gaussian distribution below T{sub c}, decreases above T{sub c}. Although the color diagonal ghost propagator is temperature independent, the l{sup 1} norm of the color antisymmetric ghost propagator is temperature dependent. The expectation value of the ghost condensate observed at zero-temperature unquenched configuration is consistent with 0 in T>T{sub c}. We also measure transverse, magnetic, and electric gluon propagator and extract gluon screening masses. The running coupling measured from the product of the gluon dressing function and the ghost dressing function are almost temperature independent, but the effect of A{sup 2} condensate observed at zero temperature is consistent with 0 in T>T{sub c}. The transverse gluon dressing function at low temperature has a peak in the infrared at low temperature, but it becomes flatter at high temperature. The magnetic gluon propagator at high momentum depends on the temperature. These data imply that the magnetic gluon propagator and the color antisymmetric ghost propagator are affected by the presence of dynamical quarks, and there are strong nonperturbative effects through the temperature-dependent color antisymmetric ghost propagator.

  1. Excited-State Effective Masses in Lattice QCD

    SciTech Connect

    George Fleming, Saul Cohen, Huey-Wen Lin

    2009-10-01

    We apply black-box methods, i.e. where the performance of the method does not depend upon initial guesses, to extract excited-state energies from Euclidean-time hadron correlation functions. In particular, we extend the widely used effective-mass method to incorporate multiple correlation functions and produce effective mass estimates for multiple excited states. In general, these excited-state effective masses will be determined by finding the roots of some polynomial. We demonstrate the method using sample lattice data to determine excited-state energies of the nucleon and compare the results to other energy-level finding techniques.

  2. Uncertainty quantification in lattice QCD calculations for nuclear physics

    NASA Astrophysics Data System (ADS)

    Beane, Silas R.; Detmold, William; Orginos, Kostas; Savage, Martin J.

    2015-03-01

    The numerical technique of lattice quantum chromodynamics (LQCD) 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. We review the sources of uncertainty inherent in LQCD calculations for nuclear physics, and discuss how each is quantified in current efforts.

  3. The Ds and D+ Leptonic Decay Constants from Lattice QCD

    SciTech Connect

    Bazavov, A.; Bernard, C.; DeTar, C.; Freeland, E.D.; Gamiz, E.; Gottlieb, Steven; Heller, U.M.; Hetrick, J.E.; El-Khadra, A.X.; Kronfeld, A.S.; Laiho, J.; /Washington U., St. Louis /Utah U.

    2009-12-01

    We present the leptonic decay constants f{sub D{sub s}} and f{sub D{sup +}} computed on the MILC collaboration's 2+1 flavor asqtad gauge ensembles. We use clover heavy quarks with the Fermilab interpretation and improved staggered light quarks. The simultaneous chiral and continuum extrapolation, which determines both decay constants, includes partially-quenched lattice results at lattice spacings a {approx} 0.09, 0.12 and 0.15 fm. We have made several recent improvements in our analysis: (a) we include terms in the fit describing leading order heavy-quark discretization effects, (b) we have adopted a more precise input r{sub 1} value consistent with our other D and B meson studies, (c) we have retuned the input bare charm masses based upon the new r{sub 1}. Our preliminary results are f{sub D{sub s}} = 260 {+-} 10 MeV and f{sub D{sup +}} = 217 {+-} 10 MeV.

  4. The effects of QCD equation of state on the relic density of WIMP dark matter

    SciTech Connect

    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.

  5. Resonance Parameters of the Rho-Meson from Lattice QCD

    SciTech Connect

    Xu Feng, Karl Jansen, Dru Renner

    2011-05-01

    We perform a non-perturbative lattice calculation of the P-wave pion-pion scattering phase in the rho-meson decay channel using two flavors of maximally twisted mass fermions at pion masses ranging from 480 MeV to 290 MeV. Making use of finite-size methods, we evaluate the pion-pion scattering phase in the center-of-mass frame and two moving frames. Applying an effective range formula, we find a good description of our results for the scattering phase as a function of the energy covering the resonance region. This allows us to extract the rho-meson mass and decay width and to study their quark mass dependence.

  6. Resonance parameters of the {rho} meson from lattice QCD

    SciTech Connect

    Feng Xu; Jansen, Karl; Renner, Dru B.

    2011-05-01

    We perform a nonperturbative lattice calculation of the P-wave pion-pion scattering phase in the {rho}-meson decay channel using two flavors of maximally twisted mass fermions at pion masses ranging from 480 to 290 MeV. Making use of finite-size methods, we evaluate the pion-pion scattering phase in the center-of-mass frame and two moving frames. Applying an effective range formula, we find a good description of our results for the scattering phase as a function of the energy covering the resonance region. This allows us to extract the {rho}-meson mass and decay width and to study their quark mass dependence.

  7. SU(2) Low-Energy Constants from Mixed-Action Lattice QCD

    SciTech Connect

    Silas Beane, William Detmold, Parikshit Junnarkar, T.C. Luu, Konstantinos Orginos, Assumpta Parreno, Martin Savage, Aaron Torok, Andre Walker-Loud

    2012-11-01

    An analysis of the pion mass and pion decay constant is performed using mixed-action Lattice QCD calculations with domain-wall valence quarks on ensembles of rooted, staggered n_f = 2+1 MILC configurations. Calculations were performed at two lattice spacings of b~0.125 fm and b~0.09 fm, at two strange quark masses, multiple light quark masses, and a number of lattice volumes. The ratios of light quark to strange quark masses are in the range 0.1 <= m_l / m_s <= 0.6, while pion masses are in the range 235 < m_\\pi < 680 MeV. A two-flavor chiral perturbation theory analysis of the Lattice QCD calculations constrains the Gasser-Leutwyler coefficients bar{l}_3 and bar{l}_4 to be bar{l}_3 = 4.04(40)(+73-55) and bar{l}_4 = 4.30(51)(+84-60). All systematic effects in the calculations are explored, including those from the finite lattice space-time volume, the finite lattice spacing, and the finite fifth dimension in the domain-wall quark action. A consistency is demonstrated between a chiral perturbation theory analysis at fixed lattice spacing combined with a leading order continuum extrapolation, and the mixed-action chiral perturbation theory analysis which explicitly includes the leading order discretization effects. Chiral corrections to the pion decay constant are found to give f_\\pi / f = 1.062(26)(+42-40) where f is the decay constant in the chiral limit. The most recent scale setting by the MILC Collaboration yields a postdiction of f_\\pi = 128.2(3.6)(+4.4-6.0)(+1.2-3.3) MeV at the physical pion mass.

  8. Renormalization of operators for excited-state hadrons in lattice QCD.

    SciTech Connect

    Ekaterina Mastropas, David Richards

    2012-04-01

    One of the primary aims of lattice QCD is to accurately compute the spectrum of hadronic excitations from first principles. However, obtaining an accurate resolution of excited states using methods of lattice QCD is not a trivial problem due to faster decay of excited-states correlation functions in Euclidean space in comparison to those of ground states. To overcome this difficulty, anisotropic lattices with a finer temporal discretization are used. To go beyond the spectrum, in order to study the properties of the states, one needs to compute corresponding matrix elements. Thus, for example, the quark distribution amplitudes in mesons are given by matrix elements of quark bilinear operators, while in baryons, the corresponding quark distribution amplitudes are related to matrix elements of three-quark operators. To relate the matrix elements calculated on the lattice to those in the continuum, and hence to relate to the measured experimentally, it is necessary to evaluate matching coefficients. In this work we describe the calculation of the matching coefficients using perturbation theory for the improved anisotropic-clover fermion action used for our studies of excited states.

  9. Potential description of the charmonium from lattice QCD

    NASA Astrophysics Data System (ADS)

    Kawanai, Taichi; Sasaki, Shoichi

    2016-01-01

    We present spin-independent and spin-spin interquark potentials for charmonium states, that are calculated using a relativistic heavy quark action for charm quarks on the PACS-CS gauge configurations generated with the Iwasaki gauge action and 2+1 flavors of Wilson clover quark. The interquark potential with finite quark masses is defined through the equal-time Bethe-Salpeter amplitude. The light and strange quark masses are close to the physical point where the pion mass corresponds to Mπ ≈ 156(7) MeV, and charm quark mass is tuned to reproduce the experimental values of ηc and J/ψ states. Our simulations are performed with a lattice cutoff of a-1 ≈ 2.2 GeV and a spatial volume of (3 fm)3. We solve the nonrelativistic Schrödinger equation with resulting charmonium potentials as theoretical inputs. The resultant charmonium spectrum below the open charm threshold shows a fairly good agreement with experimental data of well-established charmonium states.

  10. Isospin splittings in the light-baryon octet from lattice QCD and QED.

    PubMed

    Borsanyi, Sz; Dürr, S; Fodor, Z; Frison, J; Hoelbling, C; Katz, S D; Krieg, S; Kurth, Th; Lellouch, L; Lippert, Th; Portelli, A; Ramos, A; Sastre, A; Szabo, K

    2013-12-20

    While electromagnetic and up-down quark mass difference effects on octet baryon masses are very small, they have important consequences. The stability of the hydrogen atom against beta decay is a prominent example. Here, we include these effects by adding them to valence quarks in a lattice QCD calculation based on Nf=2+1 simulations with five lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. This allows us to gain control over all systematic errors, except for the one associated with neglecting electromagnetism in the sea. We compute the octet baryon isomultiplet mass splittings, as well as the individual contributions from electromagnetism and the up-down quark mass difference. Our results for the total splittings are in good agreement with experiment. PMID:24483739

  11. An analysis of the nucleon spectrum from lattice partially-quenched QCD

    SciTech Connect

    W. Armour; Allton, C. R.; Leinweber, Derek B.; Thomas, Anthony W.; Young, Ross D.

    2010-09-01

    The chiral extrapolation of the nucleon mass, Mn, is investigated using data coming from 2-flavour partially-quenched lattice simulations. The leading one-loop corrections to the nucleon mass are derived for partially-quenched QCD. A large sample of lattice results from the CP-PACS Collaboration is analysed, with explicit corrections for finite lattice spacing artifacts. The extrapolation is studied using finite range regularised chiral perturbation theory. The analysis also provides a quantitative estimate of the leading finite volume corrections. It is found that the discretisation, finite-volume and partial quenching effects can all be very well described in this framework, producing an extrapolated value of Mn in agreement with experiment. This procedure is also compared with extrapolations based on polynomial forms, where the results are less encouraging.

  12. Excited-state spectroscopy of singly, doubly and triply-charmed baryons from lattice QCD

    SciTech Connect

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

    2014-07-01

    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. These operators transform as irreducible representations of SU(3)F symmetry for flavour, SU(4) symmetry for Dirac spins of quarks and O(3) symmetry for orbital angular momenta. 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)ⓍO(3) symmetry.

  13. Scattering in the πN negative parity channel in lattice QCD

    NASA Astrophysics Data System (ADS)

    Lang, C. B.; Verduci, V.

    2013-03-01

    We study the coupled πN system (negative parity, isospin (1)/(2)) based on a lattice QCD simulation for nf=2 mass degenerate light quarks. Both standard 3-quark baryon operators as well as meson-baryon (4+1)-quark operators are included. This is an exploratory study for just one lattice size and lattice spacing and at a pion mass of 266 MeV. Using the distillation method and variational analysis we determine energy levels of the lowest eigenstates. Comparison with the results of simple 3-quark correlation studies exhibits drastic differences and a new level appears. A clearer picture of the negative parity nucleon spectrum emerges. For the parameters of the simulation we may assume elastic s-wave scattering and can derive values of the phase shift.

  14. Nucleon, $$\\Delta$$ and $$\\Omega$$ excited states in $N_f=2+1$ lattice QCD

    DOE PAGESBeta

    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

  15. State of the art lattice results of QCD with light flavours

    NASA Astrophysics Data System (ADS)

    Ramos, Alberto; Budapest-Marseille-Wuppertal Collaboration

    2010-10-01

    Thanks to recent developments both in our understanding of lattice simulations and in computer power, lattice gauge theory now allows to perform non perturbative QCD computations with all the sources of error under control. I will review some recent results of the Budapest-Marseille-Wuppertal (BMW) collaboration: first computing the mass of the hadrons, an old desire of every particle physicist. Second π and K decay constants can be used to compute CKM matrix elements and constrain physics beyond the standard model. Finally we will see how the lattice can be used to compute quantities not directly accessible to experiments, but anyhow interesting such as the nucleon sigma terms. I will emphasise how the different sources of error are controlled to make physical predictions.

  16. Color fields computed in SU(3) lattice QCD for the static tetraquark system

    NASA Astrophysics Data System (ADS)

    Cardoso, Nuno; Cardoso, Marco; Bicudo, Pedro

    2011-09-01

    The color fields created by the static tetraquark system are computed in quenched SU(3) lattice QCD, in a 243×48 lattice at β=6.2 corresponding to a lattice spacing a=0.07261(85)fm. We find that the tetraquark color fields are well described by a double-Y, or butterfly, shaped flux tube. The two flux-tube junction points are compatible with Fermat points minimizing the total flux-tube length. We also compare the diquark-diantiquark central flux-tube profile in the tetraquark with the quark-antiquark fundamental flux-tube profile in the meson, and they match, thus showing that the tetraquark flux tubes are composed of fundamental flux tubes.

  17. Color fields of the static pentaquark system computed in SU(3) lattice QCD

    NASA Astrophysics Data System (ADS)

    Cardoso, Nuno; Bicudo, Pedro

    2013-02-01

    We compute the color fields of SU(3) lattice QCD created by static pentaquark systems, in a 243×48 lattice at β=6.2 corresponding to a lattice spacing a=0.07261(85)fm. We find that the pentaquark color fields are well described by a multi-Y-type shaped flux tube. The flux tube junction points are compatible with Fermat-Steiner points minimizing the total flux tube length. We also compare the pentaquark flux tube profile with the diquark-diantiquark central flux tube profile in the tetraquark and the quark-antiquark fundamental flux tube profile in the meson, and they match, thus showing that the pentaquark flux tubes are composed of fundamental flux tubes.

  18. Perfect Abelian dominance of confinement in quark-antiquark potential in SU(3) lattice QCD

    NASA Astrophysics Data System (ADS)

    Suganuma, Hideo; Sakumichi, Naoyuki

    2016-01-01

    In the context of the dual superconductor picture for the confinement mechanism, we study maximally Abelian (MA) projection of quark confinement in SU(3) quenched lattice QCD with 324 at β=6.4 (i.e., a ≃ 0.058 fm). We investigate the static quark-antiquark potential V(r), its Abelian part VAbel(r) and its off-diagonal part Voff(r), respectively, from the on-axis lattice data. As a remarkable fact, we find almost perfect Abelian dominance for quark confinement, i.e., σAbel ≃ σ for the string tension, on the fine and large-volume lattice. We find also a nontrivial summation relation of V (r) ≃ VAbel(r)+Voff(r).

  19. Lattice study on QCD-like theory with exact center symmetry

    NASA Astrophysics Data System (ADS)

    Iritani, Takumi; Itou, Etsuko; Misumi, Tatsuhiro

    2015-11-01

    We investigate QCD-like theory with exact center symmetry, with emphasis on the finite-temperature phase transition concerning center and chiral symmetries. On the lattice, we formulate center symmetric SU(3) gauge theory with three fundamental Wilson quarks by twisting quark boundary conditions in a compact direction ( Z 3-QCD model). We calculate the expectation value of Polyakov loop and the chiral condensate as a function of temperature on 163 × 4 and 203 × 4 lattices along the line of constant physics realizing m PS / m V = 0.70. We find out the first-order center phase transition, where the hysteresis of the magnitude of Polyakov loop exists depending on thermalization processes. We show that chiral condensate decreases around the critical temperature in a similar way to that of the standard three-flavor QCD, as it has the hysteresis in the same range as that of Polyakov loop. We also show that the flavor symmetry breaking due to the twisted boundary condition gets qualitatively manifest in the high-temperature phase. These results are consistent with the predictions based on the chiral effective model in the literature. Our approach could provide novel insights to the nonperturbative connection between the center and chiral properties.

  20. |Vu b| from B →π ℓν decays and (2 +1 )-flavor lattice QCD

    NASA Astrophysics Data System (ADS)

    Bailey, Jon. A.; Bazavov, A.; Bernard, C.; Bouchard, C. M.; DeTar, C.; Du, D.; El-Khadra, A. X.; Foley, J.; Freeland, E. D.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Komijani, J.; Kronfeld, A. S.; Laiho, J.; Levkova, L.; Liu, Yuzhi; Mackenzie, P. B.; Meurice, Y.; Neil, E.; Qiu, Si-Wei; Simone, J. N.; Sugar, R.; Toussaint, D.; Van de Water, R. S.; Zhou, R.; Fermilab Lattice; MILC Collaborations

    2015-07-01

    We present a lattice-QCD calculation of the B →π ℓν semileptonic form factors and a new determination of the CKM matrix element |Vu b|. We use the MILC asqtad (2 +1 )-flavor lattice configurations at four lattice spacings and light-quark masses down to 1 /20 of the physical strange-quark mass. We extrapolate the lattice form factors to the continuum using staggered chiral perturbation theory in the hard-pion and SU(2) limits. We employ a model-independent z parametrization to extrapolate our lattice form factors from large-recoil momentum to the full kinematic range. We introduce a new functional method to propagate information from the chiral-continuum extrapolation to the z expansion. We present our results together with a complete systematic error budget, including a covariance matrix to enable the combination of our form factors with other lattice-QCD and experimental results. To obtain |Vu b|, we simultaneously fit the experimental data for the B →π ℓν differential decay rate obtained by the BABAR and Belle collaborations together with our lattice form-factor results. We find |Vu b|=(3.72 ±0.16 )×10-3 , where the error is from the combined fit to lattice plus experiments and includes all sources of uncertainty. Our form-factor results bring the QCD error on |Vu b| to the same level as the experimental error. We also provide results for the B →π ℓν vector and scalar form factors obtained from the combined lattice and experiment fit, which are more precisely determined than from our lattice-QCD calculation alone. These results can be used in other phenomenological applications and to test other approaches to QCD.

  1. Static quark-antiquark potential in the quark-gluon plasma from lattice QCD.

    PubMed

    Burnier, Yannis; Kaczmarek, Olaf; Rothkopf, Alexander

    2015-02-27

    We present a state-of-the-art determination of the complex valued static quark-antiquark potential at phenomenologically relevant temperatures around the deconfinement phase transition. Its values are obtained from nonperturbative lattice QCD simulations using spectral functions extracted via a novel Bayesian inference prescription. We find that the real part, both in a gluonic medium, as well as in realistic QCD with light u, d, and s quarks, lies close to the color singlet free energies in Coulomb gauge and shows Debye screening above the (pseudo)critical temperature T_{c}. The imaginary part is estimated in the gluonic medium, where we find that it is of the same order of magnitude as in hard-thermal loop resummed perturbation theory in the deconfined phase. PMID:25768756

  2. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, HADRON STRUCTURE FROM LATTICE QCD, MARCH 18 - 22, 2002, BROOKHAVEN NATIONAL LABORATORY.

    SciTech Connect

    BLUM, T.; BOER, D.; CREUTZ, M.; OHTA, S.; ORGINOS, K.

    2002-03-18

    The RIKEN BNL Research Center workshop on ''Hadron Structure from Lattice QCD'' was held at BNL during March 11-15, 2002. Hadron structure has been the subject of many theoretical and experimental investigations, with significant success in understanding the building blocks of matter. The nonperturbative nature of QCD, however, has always been an obstacle to deepening our understanding of hadronic physics. Lattice QCD provides the tool to overcome these difficulties and hence a link can be established between the fundamental theory of QCD and hadron phenomenology. Due to the steady progress in improving lattice calculations over the years, comparison with experimentally measured hadronic quantities has become important. In this respect the workshop was especially timely. By providing an opportunity for experts from the lattice and hadron structure communities to present their latest results, the workshop enhanced the exchange of knowledge and ideas. With a total of 32 registered participants and 26 talks, the interest of a growing community is clearly exemplified. At the workshop Schierholz and Negele presented the current status of lattice computations of hadron structure. Substantial progress has been made during recent years now that the quenched results are well under control and the first dynamical results have appeared. In both the dynamical and the quenched simulations the lattice results, extrapolated to lighter quark masses, seem to disagree with experiment. Melnitchouk presented a possible explanation (chiral logs) for this disagreement. It became clear from these discussions that lattice computations at significantly lighter quark masses need to be performed.

  3. Exotic and excited-state radiative transitions in charmonium from lattice QCD

    DOE PAGESBeta

    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

  4. Exotic and excited-state radiative transitions in charmonium from lattice QCD

    SciTech Connect

    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 exotic $1^{-+}$ $\\eta_{c1}$ 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

  5. The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD

    SciTech Connect

    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 enough 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(mπ2χ2). 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.

  6. Neutron and proton electric dipole moments from Nf=2+1 domain-wall fermion lattice QCD

    DOE PAGESBeta

    Shintani, Eigo; Blum, Thomas; Izubuchi, Taku; Soni, Amarjit

    2016-05-05

    We present a lattice calculation of the neutron and proton electric dipole moments (EDM’s) with Nf = 2 + 1 flavors of domain-wall fermions. The neutron and proton EDM form factors are extracted from three-point functions at the next-to-leading order in the θ vacuum of QCD. In this computation, we use pion masses 330 and 420 MeV and 2.7 fm3 lattices with Iwasaki gauge action and a 170 MeV pion and 4.6 fm3 lattice with I-DSDR gauge action, all generated by the RBC and UKQCD collaborations. The all-mode-averaging technique enables an efficient, high statistics calculation; however the statistical errors onmore » our results are still relatively large, so we investigate a new direction to reduce them, reweighting with the local topological charge density which appears promising. Furthermore, we discuss the chiral behavior and finite size effects of the EDM’s in the context of baryon chiral perturbation theory.« less

  7. Hadronic light-by-light scattering contribution to the muon anomalous magnetic moment from lattice QCD

    SciTech Connect

    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.

  8. Lattice QCD studies of s-wave meson-baryon interactions

    SciTech Connect

    Ikeda, Yoichi

    2011-10-21

    We study the s-wave KN interactions in the isospin I = 0, 1 channels and associated exotic state {Theta}{sup +} from 2+1 flavor full lattice QCD simulation for relatively heavy quark mass corresponding to m{sub {pi}} = 871 MeV. The s-wave KN potentials are obtained from the Bethe-Salpeter amplitudes. Potentials in both channels reveal short range repulsions: Strength of the repulsion is stronger in the I = 1 potential. The I = 0 potential is found to have attractive well at mid range. The KN scattering phase shifts are calculated and compared with the experimental data.

  9. Progress Report on Computing Excited-State Hadron Masses in Lattice QCD

    SciTech Connect

    Morningstar, C.; Bell, A.; Lenkner, D.; Wong, C. H.; Bulava, J.; Foley, J.; Juge, K. J.

    2011-10-21

    Our progress in computing the spectrum of excited baryons and mesons in lattice QCD is described. Sets of spatially-extended hadron operators with a variety of different momenta are used. A new method of stochastically estimating the low-lying effects of quark propagation is utilized which allows reliable determinations of temporal correlations of both single-hadron and multi-hadron operators. The method is tested on the isoscalar mesons in the scalar, pseudoscalar, and vector channels, and on the two-pion system of total isospin I = 0,1,2.

  10. Nucleon scalar and tensor charges from lattice QCD with light Wilson quarks

    NASA Astrophysics Data System (ADS)

    Green, J. R.; Negele, J. W.; Pochinsky, A. V.; Syritsyn, S. N.; Engelhardt, M.; Krieg, S.

    2012-12-01

    We present 2+1 flavor lattice QCD calculations of the nucleon scalar and tensor charges. Using the BMW clover-improved Wilson action with pion masses between 149 and 356 MeV and three source-sink separations between 0.9 and 1.4 fm, we achieve good control over excited-state contamination and extrapolation to the physical pion mass. As a consistency check, we also present results from calculations using unitary domain wall fermions with pion masses between 297 and 403 MeV, and using domain wall valence quarks and staggered sea quarks with pion masses between 293 and 597 MeV.

  11. Precise Determination of the I = 2 Scattering Length from Mixed-Action Lattice QCD

    SciTech Connect

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

    2008-01-01

    The I=2 pipi scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations (with fourth-rooted staggered sea quarks) at four light-quark masses. Two- and three-flavor mixed-action chiral perturbation theory at next-to-leading order is used to perform the chiral and continuum extrapolations. At the physical charged pion mass, we find m_pi a_pipi(I=2) = -0.04330 +- 0.00042, where the error bar combines the statistical and systematic uncertainties in quadrature.

  12. Relevant gluonic energy scale of spontaneous chiral symmetry breaking from lattice QCD

    SciTech Connect

    Yamamoto, Arata; Suganuma, Hideo

    2010-01-01

    We analyze which momentum component of the gluon field induces spontaneous chiral symmetry breaking in lattice QCD. After removing the high-momentum or low-momentum component of the gluon field, we calculate the chiral condensate and observe the roles of these momentum components. The chiral condensate is found to be drastically reduced by removing the zero-momentum gluon. The reduction is about 40% of the total in our calculation condition. The nonzero-momentum infrared gluon also has a sizable contribution to the chiral condensate. From the Banks-Casher relation, this result reflects the nontrivial relation between the infrared gluon and the zero-mode quark.

  13. Extracting Nucleon Magnetic Moments and Electric Polarizabilities from Lattice QCD in Background Electric Fields

    SciTech Connect

    William Detmold; Tiburzi, Brian C.; Walker-Loud, Andre

    2010-03-01

    Nucleon properties are investigated in background electric fields. As the magnetic moments of baryons affect their relativistic propagation in constant electric fields, electric polarizabilities cannot be determined without knowledge of magnetic moments. We devise combinations of baryon two-point functions in external electric fields to isolate both observables. Using an ensemble of anisotropic gauge configurations with dynamical clover fermions, we demonstrate how magnetic moments and electric polarizabilities can be determined from lattice QCD simulations in background electric fields. We obtain results for both the neutron and proton. Our study is currently limited to electrically neutral sea quarks.

  14. First study of the three-gluon static potential in lattice QCD

    NASA Astrophysics Data System (ADS)

    Cardoso, M.; Bicudo, P.

    2008-10-01

    We estimate the potential energy for a system of three static gluons in lattice QCD. This is relevant for the different models of three-body glueballs that have been proposed in the literature, either for gluons with a constituent mass, or for massless ones. A Wilson loop adequate to the static hybrid three-body system is developed. We study different spacial geometries, to compare the starfish model with the triangle model, for the three-gluon potential. We also study two different color structures, symmetric and antisymmetric, and compare the respective static potentials. A first simulation is performed in a 243×48 periodic Lattice, with β=6.2 and ã0.072fm.

  15. High-Performance I/O: HDF5 for Lattice QCD

    SciTech Connect

    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.

  16. Hyperon vector coupling f{sub 1}(0) from 2+1 flavor lattice QCD

    SciTech Connect

    Sasaki, Shoichi

    2011-10-21

    We present results for the hyperon vector form factor f{sub 1} for {Xi}{sup 0}{yields}{Sigma}{sup +}l{nu}-bar and {Sigma}{sup -}{yields}nl{nu}-bar semileptonic decays from dynamical lattice QCD with domain-wall quarks. Simulations are performed on the 2+1 flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice cutoff of a{sup -1} = 1.7 GeV. Our preliminary results, which are calculated at the lightest sea quark mass (pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on hyperon vector coupling f{sub 1}(0) is likely negative.

  17. Short-distance matrix elements for $D$-meson mixing for 2+1 lattice QCD

    SciTech Connect

    Chang, Chia Cheng

    2015-01-01

    We study the short-distance hadronic matrix elements for D-meson mixing with partially quenched Nf = 2+1 lattice QCD. We use a large set of the MIMD Lattice Computation Collaboration's gauge configurations with a2 tadpole-improved staggered sea quarks and tadpole-improved Lüscher-Weisz gluons. We use the a2 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.

  18. Direct Evaluation of the Quark Content of Nucleons from Lattice QCD at the Physical Point.

    PubMed

    Abdel-Rehim, A; Alexandrou, C; Constantinou, M; Hadjiyiannakou, K; Jansen, K; Kallidonis, Ch; Koutsou, G; Avilés-Casco, A Vaquero

    2016-06-24

    We evaluate the light, strange, and charm scalar content of the nucleon using one lattice QCD ensemble generated with two degenerate light quarks with mass fixed to their physical value. We use improved techniques to evaluate the disconnected quark loops to sufficient accuracy to determine the strange and charm nucleon σ terms in addition to the light quark content σ_{πN}. We find σ_{πN}=37.2(2.6)(4.7/2.9)  MeV, σ_{s}=41.1(8.2)(7.8/5.8)  MeV, and σ_{c}=79(21)(12/8)  MeV, where the first error is statistical and the second is the systematic error due to the determination of the lattice spacing, the assessment of finite volume, and residual excited state effects. PMID:27391717

  19. Crossover Equation of State Compared to Lattice QCD and to Baryon Fluctuations in the RHIC Beam Energy Scan

    NASA Astrophysics Data System (ADS)

    Kapusta, Joseph; Albright, Michael; Young, Clint

    2015-10-01

    We match hadronic equations of state at low energy densities to a perturbatively computed equation of state of quarks and gluons at high energy densities. The hadronic equations of state include all known hadrons; repulsive interactions are taken into account via two versions of the excluded volume approximation. A switching function is employed to make the crossover transition from one phase to another without introducing a thermodynamic phase transition. A fit to accurate lattice calculations of the pressure and trace anomaly, with temperature 100 < T < 1000 MeV and μ = 0 , determines the parameters. These parameters quantify the behavior of the QCD running gauge coupling and the hard core radius of the nucleon. With no new parameters, the pressure and trace anomaly from lattice calculations for μ = 400 MeV are equally well reproduced, as is the speed of sound. We then compute the skewness and kurtosis and compare to measurements of the fluctuations of the proton number distribution in central Au-Au collisions as measured by the STAR collaboration in a beam energy scan at RHIC. The crossover equations of state can reproduce the data if the fluctuations are frozen at a temperature significantly lower than the average chemical freeze-out. This work was supported by the US Department of Energy under Grant No. DE-FG02-87ER40328.

  20. SU(2) low-energy constants from mixed-action lattice QCD

    NASA Astrophysics Data System (ADS)

    Beane, S. R.; Detmold, W.; Junnarkar, P. M.; Luu, T. C.; Orginos, K.; Parreño, A.; Savage, M. J.; Torok, A.; Walker-Loud, A.

    2012-11-01

    An analysis of the pion mass and pion decay constant is performed using mixed-action lattice QCD calculations with domain-wall valence quarks on ensembles of rooted, staggered nf=2+1 configurations generated by the MILC Collaboration. Calculations were performed at two lattice spacings of b≈0.125fm and b≈0.09fm, at two strange quark masses, multiple light quark masses, and a number of lattice volumes. The ratios of light quark to strange quark masses are in the range 0.1≤ml/ms≤0.6, while pion masses are in the range 235≲mπ≲680MeV. A two-flavor chiral perturbation theory analysis of the lattice QCD calculations constrains the Gasser-Leutwyler coefficients l¯3 and l¯4 to be l¯3=4.04(40)((73)/(55)) and l¯4=4.30(51)((84)/(60)). All systematic effects in the calculations are explored, including those from the finite lattice space-time volume, the finite lattice spacing, and the finite fifth dimension in the domain-wall quark action. A consistency is demonstrated between a chiral perturbation theory analysis at fixed lattice spacing combined with a leading order continuum extrapolation, and the mixed-action chiral perturbation theory analysis which explicitly includes the leading order discretization effects. Chiral corrections to the pion decay constant are found to give fπ/f=1.062(26)((42)/(40)) where f is the decay constant in the chiral limit, and when combined with the experimental determination of fπ results in a value of f=122.8(3.0)((4.6)/(4.8))MeV. The most recent scale setting by the MILC Collaboration yields a postdiction of fπ=128.2(3.6)((4.4)/(6.0))((1.2)/(3.3))MeV at the physical pion mass. A detailed error analysis indicates that precise calculations at lighter pion masses is the single most important systematic to address to improve upon the present work.

  1. Baryon spin-flavor structure from an analysis of lattice QCD results of the baryon spectrum

    DOE PAGESBeta

    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

  2. Baryon spin-flavor structure from an analysis of lattice QCD results of the baryon spectrum

    SciTech Connect

    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, 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.

  3. Lattice QCD evidence that the Λ(1405) resonance is an antikaon-nucleon molecule.

    PubMed

    Hall, Jonathan M M; Kamleh, Waseem; Leinweber, Derek B; Menadue, Benjamin J; Owen, Benjamin J; Thomas, Anthony W; Young, Ross D

    2015-04-01

    For almost 50 years the structure of the Λ(1405) resonance has been a mystery. Even though it contains a heavy strange quark and has odd parity, its mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers speculated that it might be a molecular state of an antikaon bound to a nucleon. However, a standard quark-model structure is also admissible. Although the intervening years have seen considerable effort, there has been no convincing resolution. Here we present a new lattice QCD simulation showing that the strange magnetic form factor of the Λ(1405) vanishes, signaling the formation of an antikaon-nucleon molecule. Together with a Hamiltonian effective-field-theory model analysis of the lattice QCD energy levels, this strongly suggests that the structure is dominated by a bound antikaon-nucleon component. This result clarifies that not all states occurring in nature can be described within a simple quark model framework and points to the existence of exotic molecular meson-nucleon bound states. PMID:25884122

  4. Lattice QCD analysis for relation between quark confinement and chiral symmetry breaking

    NASA Astrophysics Data System (ADS)

    Doi, Takahiro M.; Suganuma, Hideo; Iritani, Takumi

    2016-01-01

    The Polyakov loop and the Dirac modes are connected via a simple analytical relation on the temporally odd-number lattice, where the temporal lattice size is odd with the normal (nontwisted) periodic boundary condition. Using this relation, we investigate the relation between quark confinement and chiral symmetry breaking in QCD. In this paper, we discuss the properties of this analytical relation and numerically investigate each Dirac-mode contribution to the Polyakov loop in both confinement and deconfinement phases at the quenched level. This relation indicates that low-lying Dirac modes have little contribution to the Polyakov loop, and we numerically confirmed this fact. From our analysis, it is suggested that there is no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD. Also, in the confinement phase, we numerically find that there is a new "positive/negative symmetry" in the Dirac-mode matrix elements of link-variable operator which appear in the relation and the Polyakov loop becomes zero because of this symmetry. In the deconfinement phase, this symmetry is broken and the Polyakov loop is non-zero.

  5. On the Baryonic Density and Susceptibilities in a Holographic Model of QCD

    SciTech Connect

    Kim, Keun-young; Liao, Jinfeng

    2009-06-16

    In this paper, we calculate analytically the baryonic density and susceptibilities, which are sensitive probes to the fermionic degrees of freedom, in a holographic model of QCD both in its hot QGP phase and in its cold dense phase. Interesting patterns due to strong coupling dynamics will be shown and valuable lessons for QCD will be discussed.

  6. Strong coupling constant from vacuum polarization functions in three-flavor lattice QCD with dynamical overlap fermions

    SciTech Connect

    Shintani, E.; Aoki, S.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Onogi, T.; Yamada, N.

    2010-10-25

    We determine the strong coupling constant {alpha}{sub s} from a lattice calculation of vacuum polarization functions (VPF) in three-flavor QCD with dynamical overlap fermions. Fitting lattice data of VPF to the continuum perturbative formula including the operator product expansion, we extract the QCD scale parameter {Lambda}{sub MS}{sup -(3)}. At the Z boson mass scale, we obtain {alpha}{sub s}{sup (5)}(M{sub z}) = 0.1181(3)(+14/-12), where the first error is statistical and the second is our estimate of various systematic uncertainties.

  7. Valence quark contribution for the gamma N -> Delta quadrupole transition extracted from lattice QCD

    SciTech Connect

    Ramalho, Gilberto; Haderer De La Pena S, Maria

    2009-01-01

    Starting with a spectator quark model developed for the nucleon (N) and the Delta in the physical pion mass region, we extend the predictions of the reaction gamma N -> Delta to the lattice QCD regime. The quark model includes S and D waves in the quark-diquark wavefunctions. Within this framework it is the D-wave part in the Delta wavefunction that generates nonzero valence contributions for the quadrupole form factors of the transition. Those contributions are however insufficient to explain the physical data, since the pion cloud contributions dominate. To separate the two effects we apply the model to the lattice regime in a region where the pion cloud effects are negligible, and adjust the D-state parameters directly to the lattice data. This process allows us to obtain a better determination of the D-state contributions. Finally, by adding a simple parametrization of the pion cloud we establish the connection between the experimental data and the lattice da

  8. Finite-size effects in lattice QCD with dynamical Wilson fermions

    SciTech Connect

    Orth, Boris; Lippert, Thomas; Schilling, Klaus

    2005-07-01

    As computing resources are limited, choosing the parameters for a full lattice QCD simulation always amounts to a compromise between the competing objectives of a lattice spacing as small, quarks as light, and a volume as large as possible. Aiming to push unquenched simulations with the Wilson action towards the computationally expensive regime of small quark masses we address the question whether one can possibly save computing time by extrapolating results from small lattices to the infinite volume, prior to the usual chiral and continuum extrapolations. In the present work the systematic volume dependence of simulated pion and nucleon masses is investigated and compared with a long-standing analytic formula by Luescher and with results from chiral perturbation theory (ChPT). We analyze data from hybrid Monte Carlo simulations with the standard (unimproved) two-flavor Wilson action at two different lattice spacings of a{approx_equal}0.08 and 0.13 fm. The quark masses considered correspond to approximately 85% and 50% (at the smaller a) and 36% (at the larger a) of the strange quark mass. At each quark mass we study at least three different lattices with L/a=10 to 24 sites in the spatial directions (L=0.85-2.08 fm). We find that an exponential ansatz fits the volume dependence of the pion masses well, but with a coefficient about an order of magnitude larger than the theoretical leading-order prediction. In the case of the nucleon we observe a remarkably good agreement between our lattice data and a recent formula from relativistic baryon ChPT.

  9. The decay constants fDs and fD+ form lattice QCD

    SciTech Connect

    Simone, James N

    2011-03-01

    Recent calculations of the decay constants in lattice QCD are reviewed and compared to experiment. The decay constants are tabulated in Table 2 and plotted in Figure 2. The most precise f{sub Ds} value is from HPQCD. It is about 2{sigma} higher than their previous result. The change is due to a more precise determination of the lattice spacing and better tuning of the quark masses. They have updated f{sub D+} using the new f{sub Ds} and their older f{sub Ds}/f{sub D+} ratio which is expected to be less sensitive to mistuning of the lattice spacing and masses. The preliminary FNAL/MILC f{sub Ds} value is about 1.4{sigma} higher than the HPQCD result but with a larger error. The f{sub D+} values, however, are in better agreement. FNAL/MILC expect to finalize their results once the charm quark mass tuning is complete. The two flavor ETM f{sub D+} value is about 1.6{sigma} lower than the HPQCD value while f{sub Ds} is in better agreement. It is not clear how much of the difference is from neglecting the strange sea quark, given the errors. Lattice and experiment differ most significantly for f{sub Ds}. Figure 3 shows Kronfeld's (updated) history of f{sub Ds}. The yellow bands depict the evolution of the experimental average while the three-flavor lattice average is shown in grey. The right-hand scale and green lines show the differences in sigmas. The 3.8{sigma} discrepancy around t {approx} 2 provoked the 'f{sub Ds} puzzle'. That discrepancy has now shrunk to 1.6{sigma}. Future lattice and experiment will be decisive.

  10. Understanding QCD at high density from a Z3 -symmetric QCD-like theory

    NASA Astrophysics Data System (ADS)

    Kouno, Hiroaki; Kashiwa, Kouji; Takahashi, Junichi; Misumi, Tatsuhiro; Yahiro, Masanobu

    2016-03-01

    We investigate QCD at large μ /T by using Z3-symmetric S U (3 ) gauge theory, where μ is the quark-number chemical potential and T is temperature. We impose the flavor-dependent twist boundary condition on quarks in QCD. This QCD-like theory has the twist angle θ as a parameter, and agrees with QCD when θ =0 and becomes symmetric when θ =2 π /3 . For both QCD and the Z3-symmetric S U (3 ) gauge theory, the phase diagram is drawn in μ -T plane with the Polyakov-loop extended Nambu-Jona-Lasinio model. In the Z3-symmetric S U (3 ) gauge theory, the Polyakov loop φ is zero in the confined phase appearing at T ≲200 MeV and μ ≲300 MeV . The perfectly confined phase never coexists with the color superconducting (CSC) phase, since finite diquark condensate in the CSC phase breaks Z3 symmetry and then makes φ finite. When μ ≳300 MeV , the CSC phase is more stable than the perfectly confined phase at T ≲100 MeV . Meanwhile, the chiral symmetry can be broken in the perfectly confined phase, since the chiral condensate is Z3 invariant. Consequently, the perfectly confined phase is divided into the perfectly confined phase without chiral symmetry restoration in a region of μ ≲300 MeV and T ≲200 MeV and the perfectly confined phase with chiral symmetry restoration in a region of μ ≳300 MeV and 100 ≲T ≲200 MeV . At low temperature, the basic phase structure of Z3-symmetric QCD-like theory remains in QCD. Properties of the sign problem in Z3-symmetric theory are also discussed. We discuss a numerical framework to evaluate observables at θ =0 from those at θ =2 π /3 .

  11. Nucleon structure in lattice QCD with dynamical domain-wall fermions quarks

    SciTech Connect

    Huey-Wen Lin; Shigemi Ohta

    2006-07-23

    We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with about 200 gauge configurations each. The lattice cutoff is about 1.7 GeV and the spatial volume is about (1.9 fm){sup 3}. Despite the small volume, the ratio of the isovector vector and axial charges g{sub A}/g{sub V} and that of structure function moments {sub u-d}/{sub {Delta} u - {Delta} d} are in agreement with experiment, and show only very mild quark mass dependence. The second, RBC/UK, set of ensembles employs one strange and two degenerate (up and down) dynamical DWF quarks and Iwasaki gauge action. The strange quark mass is set at 0.04, and three up/down mass values of 0.03, 0.02 and 0.01 in lattice units are used. The lattice cutoff is about 1.6 GeV and the spatial volume is about (3.0 fm){sup 3}. Even with preliminary statistics of 25-30 gauge configurations, the ratios g{sub A}/g{sub V} and {sub u-d}/{sub {Delta} u - {Delta} d} are consistent with experiment and show only very mild quark mass dependence. Another structure function moment, d{sub 1}, though yet to be renormalized, appears small in both sets.

  12. NUCLEON STRUCTURE IN LATTICE QCD WITH DYNAMICAL DOMAIN--WALL FERMIONS QUARKS.

    SciTech Connect

    LIN H.-W.; OHTA, S.

    2006-10-02

    We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with 220 gauge configurations each. The lattice cutoff is a{sup -1} {approx} 1.7GeV and the spatial volume is about (1.9fm){sup 3}. Despite the small volume, the ratio of the isovector vector and axial charges g{sub A}/g{sub V} and that of structure function moments {sub u-d}/{sub {Delta}u-{Delta}d} are in agreement with experiment, and show only very mild quark mass dependence. The second, RBC/UK, set of ensembles employs one strange and two degenerate (up and down) dynamical DWF quarks and Iwasaki gauge action. The strange quark mass is set at 0.04, and three up/down mass values of 0.03, 0.02 and 0.01 in lattice units are used. The lattice cutoff is a{sup -1} {approx} 1.6GeV and the spatial volume is about (3.0fm){sup 3}. Even with preliminary statistics of 25-30 gauge configurations, the ratios g{sub A}/g{sub V} and {sub u-d}/{sub {Delta}u-{Delta}d} are consistent with experiment and show only very mild quark mass dependence. Another structure function moment, d{sub 1}, though yet to be renormalized, appears small in both sets.

  13. Up and Down Quark Masses and Corrections to Dashen's Theorem from Lattice QCD and Quenched QED.

    PubMed

    Fodor, Z; Hoelbling, C; Krieg, S; Lellouch, L; Lippert, Th; Portelli, A; Sastre, A; Szabo, K K; Varnhorst, L

    2016-08-19

    In a previous Letter [Borsanyi et al., Phys. Rev. Lett. 111, 252001 (2013)] we determined the isospin mass splittings of the baryon octet from a lattice calculation based on N_{f}=2+1 QCD simulations to which QED effects have been added in a partially quenched setup. Using the same data we determine here the corrections to Dashen's theorem and the individual up and down quark masses. Our ensembles include 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashen's theorem, we obtain ϵ=0.73(2)(5)(17), where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, m_{u}=2.27(6)(5)(4) and m_{d}=4.67(6)(5)(4)  MeV in the modified minimal subtraction scheme at 2  GeV and the isospin breaking ratios m_{u}/m_{d}=0.485(11)(8)(14), R=38.2(1.1)(0.8)(1.4), and Q=23.4(0.4)(0.3)(0.4). Our results exclude the m_{u}=0 solution to the strong CP problem by more than 24 standard deviations. PMID:27588847

  14. The Neutral kaon mixing parameter B(K) from unquenched mixed-action lattice QCD

    SciTech Connect

    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.

  15. B- and D-meson decay constants from three-flavor lattice QCD

    SciTech Connect

    Bazavov, A.; et al.

    2012-06-01

    We calculate the leptonic decay constants of B_{(s)} and D_{(s)} mesons in lattice QCD using staggered light quarks and Fermilab bottom and charm quarks. We compute the heavy-light meson correlation functions on the MILC asqtad-improved staggered gauge configurations which include the effects of three light dynamical sea quarks. We simulate with several values of the light valence- and sea-quark masses (down to ~m_s/10) and at three lattice spacings (a ~ 0.15, 0.12, and 0.09 fm) and extrapolate to the physical up and down quark masses and the continuum using expressions derived in heavy-light meson staggered chiral perturbation theory. We renormalize the heavy-light axial current using a mostly nonperturbative method such that only a small correction to unity must be computed in lattice perturbation theory and higher-order terms are expected to be small. We obtain f_{B^+} = 196.9(8.9) MeV, f_{B_s} = 242.0(9.5) MeV, f_{D^+} = 218.9(11.3) MeV, f_{D_s} = 260.1(10.8) MeV, and the SU(3) flavor-breaking ratios f_{B_s}/f_{B} = 1.229(26) and f_{D_s}/f_{D} = 1.188(25), where the numbers in parentheses are the total statistical and systematic uncertainties added in quadrature.

  16. Spectroscopy of doubly and triply-charmed baryons from lattice QCD

    SciTech Connect

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

    2013-11-01

    We present the ground and excited state spectra of doubly and triply-charmed baryons by using lattice QCD with dynamical clover fermions. 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) Ⓧ 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. Using those splittings for doubly-charmed baryons, and taking input of experimental Bc meson mass, we predict the mass splittings of B*c-Bc to be about 80 ± 8 MeV and mΩccb=8050±10 MeV.

  17. Λb→pl⁻ν¯l form factors from lattice QCD with static b quarks

    DOE PAGESBeta

    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

  18. Nucleon-Nucleon Potential and Its Non-Locality in Lattice QCD

    NASA Astrophysics Data System (ADS)

    Murano, K.; Ishii, N.; Aoki, S.; Hatsuda, T.

    2011-06-01

    By the quenched lattice QCD simulation for two nucleons with finite scattering energy, validity of the derivative expansion of the general nucleon-nucleon potential U({r},{r}') = V({r}, {nabla}_{{r}}) δ^3({r}-{r}') is studied. The relative kinetic energy between two nucleons is introduced through the anti-periodic boundary condition in the spatial directions. On a hypercubic lattice with the lattice spacing a≃ 0.137 fm and the spatial extent L_{s} ≃ 4.4 fm with the pion mass m_{π}≃ 530 MeV, the local potentials for two different energies (E ≃ 0 MeV and 45 MeV) are compared and found to be identical within statistical errors, which validates the local approximation of U({r},{r}) up to E = 45 MeV for the central and tensor potentials. Central potentials in the spin-singlet channel for different orbital angular momentums (ℓ = 0 and ℓ = 2) at E ≃ 45 MeV are also found to be the same within the errors, which also supports the local approximation.

  19. Light meson electromagnetic form factors from three-flavor lattice QCD with exact chiral symmetry

    NASA Astrophysics Data System (ADS)

    Aoki, S.; Cossu, G.; Feng, X.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Onogi, T.

    2016-02-01

    We study the chiral behavior of the electromagnetic (EM) form factors of pions and kaons in three-flavor lattice QCD. In order to make a direct comparison of the lattice data with chiral perturbation theory (ChPT), we employ the overlap quark action that has exact chiral symmetry. Gauge ensembles are generated at a lattice spacing of 0.11 fm with four pion masses ranging between Mπ≃290 MeV and 540 MeV and with a strange quark mass ms close to its physical value. We utilize the all-to-all quark propagator technique to calculate the EM form factors with high precision. Their dependence on ms and on the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields, respectively. A detailed comparison with SU(2) and SU(3) ChPT reveals that the next-to-next-to-leading order terms in the chiral expansion are important to describe the chiral behavior of the form factors in the pion mass range studied in this work. We estimate the relevant low-energy constants and the charge radii, and find reasonable agreement with phenomenological and experimental results.

  20. Up and Down Quark Masses and Corrections to Dashen's Theorem from Lattice QCD and Quenched QED

    NASA Astrophysics Data System (ADS)

    Fodor, Z.; Hoelbling, C.; Krieg, S.; Lellouch, L.; Lippert, Th.; Portelli, A.; Sastre, A.; Szabo, K. K.; Varnhorst, L.; Budapest-Marseille-Wuppertal Collaboration

    2016-08-01

    In a previous Letter [Borsanyi et al., Phys. Rev. Lett. 111, 252001 (2013)] we determined the isospin mass splittings of the baryon octet from a lattice calculation based on Nf=2 +1 QCD simulations to which QED effects have been added in a partially quenched setup. Using the same data we determine here the corrections to Dashen's theorem and the individual up and down quark masses. Our ensembles include 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashen's theorem, we obtain ɛ =0.73 (2 )(5 )(17 ), where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, mu=2.27 (6 )(5 )(4 ) and md=4.67 (6 )(5 )(4 ) MeV in the modified minimal subtraction scheme at 2 G e V and the isospin breaking ratios mu/md=0.485 (11 )(8 )(14 ), R =38.2 (1.1 )(0.8 )(1.4 ), and Q =23.4 (0.4 )(0.3 )(0.4 ). Our results exclude the mu=0 solution to the strong C P problem by more than 24 standard deviations.

  1. Magnetic susceptibility of QCD at zero and at finite temperature from the lattice

    NASA Astrophysics Data System (ADS)

    Bali, G. S.; Bruckmann, F.; Constantinou, M.; Costa, M.; Endrődi, G.; Katz, S. D.; Panagopoulos, H.; Schäfer, A.

    2012-11-01

    The response of the QCD vacuum to a constant external (electro)magnetic field is studied through the tensor polarization of the chiral condensate and the magnetic susceptibility at zero and at finite temperature. We determine these quantities using lattice configurations generated with the tree-level Symanzik improved gauge action and Nf=1+1+1 flavors of stout smeared staggered quarks with physical masses. We carry out the renormalization of the observables under study and perform the continuum limit both at T>0 and at T=0, using different lattice spacings. Finite size effects are studied by using various spatial lattice volumes. The magnetic susceptibilities χf reveal a spin-diamagnetic behavior; we obtain at zero temperature χu=-(2.08±0.08)GeV-2, χd=-(2.02±0.09)GeV-2 and χs=-(3.4±1.4)GeV-2 for the up, down and strange quarks, respectively, in the MS¯ scheme at a renormalization scale of 2 GeV. We also find the polarization to change smoothly with the temperature in the confinement phase and then to drastically reduce around the transition region.

  2. Excited-state spectroscopy of triply-bottom baryons from lattice QCD

    SciTech Connect

    Stefan Meinel

    2012-06-01

    The spectrum of baryons containing three b quarks is calculated in nonperturbative QCD, using the lattice regularization. The energies of ten excited bbb states with J{sup P} = 1/2{sup +}, 3/2{sup +}, 5/2{sup +}, 7/2{sup +}, 1/2{sup -}, and 3/2{sup -} are determined with high precision. A domain-wall action is used for the up-, down- and strange quarks, and the bottom quarks are implemented with NRQCD. The computations are done at lattice spacings of a {approx} 0.11 fm and a {approx} 0.08 fm, and the results demonstrate the improvement of rotational symmetry as a is reduced. A large lattice volume of (2.7 fm){sup 3} is used, and extrapolations of the bbb spectrum to realistic values of the light sea-quark masses are performed. All spin-dependent energy splittings are resolved with total uncertainties of order 1 MeV, and the dependence of these splittings on the couplings in the NRQCD action is analyzed.

  3. Application of Quadrature Methods for Re-Weighting in Lattice QCD

    SciTech Connect

    Abdou Abdel-Rehim, William Detmold, Kostas Orginos

    2011-12-01

    Re-weighting is a useful tool that has been employed in Lattice QCD in different contexts including, tuning the strange quark mass, approaching the light quark mass regime, and simulating electromagnetic fields on top of QCD gauge configurations. In case of re-weighting the sea quark mass, the re-weighting factor is given by the ratio of the determinants of two Dirac operators D{sub a} and D{sub b}. A popular approach for computing this ratio is to use a pseudofermion representation of the determinant of the composite operator {Omega} = D{sub a}(D{sub b}{sup {dagger}}D{sub b}){sup -1} D{sub a}{sup {dagger}}. Here, we study using quadrature methods together with noise vectors to compute the ratio of determinants. We show that, with quadrature methods each determinant can be computed separately using the operators {Omega}{sub a} = D{sub a}{sup {dagger}}D{sub a} and {Omega}{sub b} = D{sub b}{sup {dagger}} D{sub b}. We also discuss using bootstrap re-sampling to remove the bias from the determinant estimator.

  4. Baryons at Varying Nc: a study with Lattice QCD and Effective Theory

    NASA Astrophysics Data System (ADS)

    Goity, Jose; Calle Cordon, Alvaro; Degrand, Thomas

    2013-10-01

    Recent Lattice QCD (LQCD) calculations of baryon masses with the number of colors Nc = 3 , 5 and 7 have opened the opportunity for exploring quantitatively the 1 /Nc expansion of QCD in the baryon sector. While similar studies have been carried out for glueballs and mesons, which show a remarkably well behaved 1 /Nc expansion down to the real world's Nc = 3 , the results in are the first ones of their kind. The calculations were performed in quenched LQCD and with quark masses giving Mπ > 400 MeV. The results are analyzed using an Effective Theory based on the combination of Baryon Chiral Perturbation Theory and the 1 /Nc expansion. A detailed discussion of the analysis and its implications will be presented, along the lines of a current work in progress. Work supported by DOE Contract No. DEAC05- 06OR23177 under which JSA operates the Thomas Jefferson National Accelerator Facility, by DOE grant DE-FG02-04ER41290, and by NSF grants PHY-0855789 and PHY-1307413.

  5. An a0 resonance in strongly coupled πη, KK¯ scattering from lattice QCD

    DOE PAGESBeta

    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

  6. High-precision determination of the pi, K, D, and Ds decay constants from lattice QCD.

    PubMed

    Follana, E; Davies, C T H; Lepage, G P; Shigemitsu, J

    2008-02-15

    We determine D and D(s) decay constants from lattice QCD with 2% errors, 4 times better than experiment and previous theory: f(D(s))=241(3) MeV, f(D)=207(4) MeV, and fD(s))/f(D)=1.164(11). We also obtain f(K)/f(pi)=1.189(7) and (f(D(s))/f(D))/(f(K)/f(pi))=0.979(11). Combining with experiment gives V(us)=0.2262(14) and V(cs)/V(cd) of 4.43(41). We use a highly improved quark discretization on MILC gluon fields that include realistic sea quarks, fixing the u/d, s, and c masses from the pi, K, and eta(c) meson masses. This allows a stringent test against experiment for D and D(s) masses for the first time (to within 7 MeV). PMID:18352458

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

    SciTech Connect

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

    2007-06-13

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

  8. Approach to the thermodynamic limit in lattice QCD at {mu}{ne}0

    SciTech Connect

    Splittorff, K.; Verbaarschot, J. J. M.

    2008-01-01

    The expectation value of the complex phase factor of the fermion determinant is computed to leading order in the p expansion of the chiral Lagrangian. The computation is valid for {mu}lattice results obtained by Allton et al. After taking appropriate limits, we reproduce previously derived results for the {epsilon} regime and for one-dimensional QCD. The distribution of the phase itself is also computed.

  9. Axion phenomenology and θ-dependence from N f = 2 + 1 lattice QCD

    NASA Astrophysics Data System (ADS)

    Bonati, Claudio; D'Elia, Massimo; Mariti, Marco; Martinelli, Guido; Mesiti, Michele; Negro, Francesco; Sanfilippo, Francesco; Villadoro, Giovanni

    2016-03-01

    We investigate the topological properties of N f = 2 + 1 QCD with physical quark masses, both at zero and finite temperature. We adopt stout improved staggered fermions and explore a range of lattice spacings a ˜ 0 .05 - 0 .12 fm. At zero temperature we estimate both finite size and finite cut-off effects, comparing our continuum extrapolated results for the topological susceptibility χ with predictions from chiral perturbation theory. At finite temperature, we explore a region going from T c up to around 4 T c , where we provide continuum extrapolated results for the topological susceptibility and for the fourth moment of the topological charge distribution. While the latter converges to the dilute instanton gas prediction the former differs strongly both in the size and in the temperature dependence. This results in a shift of the axion dark matter window of almost one order of magnitude with respect to the instanton computation.

  10. Meson-Baryon Scattering Lengths from Mixed-Action Lattice QCD

    SciTech Connect

    Will Detmold, William Detmold, Konstantinos Orginos, Aaron Torok, Silas R Beane, Thomas C Luu, Assumpta Parreno, Martin Savage, Andre Walker-Loud

    2010-04-01

    The $\\pi^+\\Sigma^+$, $\\pi^+\\Xi^0$ , $K^+p$, $K^+n$, and $K^0 \\Xi^0$ scattering lengths are calculated in mixed-action Lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations at four light-quark masses, and at two light-quark masses on the fine MILC configurations. Heavy Baryon Chiral Perturbation Theory with two and three flavors of light quarks is used to perform the chiral extrapolations. We find no convergence for the kaon-baryon processes in the three-flavor chiral expansion. Using the two-flavor chiral expansion, we find $a_{\\pi^+\\Sigma^+} = ?0.197 ± 0.017$ fm, and $a_{\\pi^+\\Xi^0} = ?0.098 0.017$ fm, where the comprehensive error includes statistical and systematic uncertainties.

  11. Fluctuations, strangeness, and quasiquarks in heavy-ion collisions from lattice QCD

    NASA Astrophysics Data System (ADS)

    Gavai, R. V.; Gupta, Sourendu

    2006-01-01

    We report measurements of diagonal susceptibilities for the baryon number, χB, electrical charge, χQ, third component of isospin, χI, strangeness, χS, and hypercharge, χY, as well as the off-diagonal χBQ, χBY, χBS, etc. We show that the ratios of susceptibilities in the high-temperature phase are robust variables, independent of lattice spacing, and therefore give predictions for experiments. We also investigate strangeness production and flavor symmetry breaking matrix elements at finite temperature. Finally, we present evidence that in the high-temperature phase of QCD the different flavor quantum numbers are excited in linkages which are exactly the same as one expects from quarks. We present some investigations of these quarklike quasiparticles.

  12. Thermodynamics of lattice QCD with massless quarks and chiral 4-fermion interactions.

    SciTech Connect

    Kogut, J. B.

    1998-10-30

    N{sub f} = 2 lattice QCD with massless quarks and a weak 4-fermion interaction appears to have the expected second order transition, at least for N{sub t} {ge} 6. More work is needed to clarify the N{sub t} = 4 case. With more statistics the N{sub t} = 6 simulations should produce an accurate determination of the critical exponent {beta}{sub m}. Moving to finite mass at {beta} = {beta}{sub c} should allow an accurate determination of {sigma}. Hadronic screening masses need further analysis. Other order parameters remain to be analyzed. Unfortunately, there is no obvious way to include 4-fermion interactions with full SU(2) x SU(2) chiral flavor symmetry.

  13. Lattice study of meson correlators in the {epsilon}-regime of two-flavor QCD

    SciTech Connect

    Fukaya, H.; Aoki, S.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Matsufuru, H.; Noaki, J.; Ogawa, K.; Onogi, T.

    2008-04-01

    We calculate mesonic two-point functions in the {epsilon}-regime of two-flavor QCD on the lattice with exact chiral symmetry. We use gauge configurations of size 16{sup 3}x32 at a{approx}0.11 fm generated with dynamical overlap fermions. The sea quark mass is fixed at around 3 MeV and the valence quark mass is varied in the range 1-4 MeV, both of which are in the {epsilon}-regime. We find a good consistency with the expectations from the next-to-leading order calculation in the {epsilon}-expansion of (partially quenched) chiral perturbation theory. From a fit we obtain the pion decay constant F=87.3(5.6) MeV and the chiral condensate {sigma}{sup MS}=[239.8(4.0) MeV]{sup 3} up to next-to-next-to-leading order contributions.

  14. Nucleon electromagnetic form factors from lattice QCD using a nearly physical pion mass

    NASA Astrophysics Data System (ADS)

    Green, J. R.; Negele, J. W.; Pochinsky, A. V.; Syritsyn, S. N.; Engelhardt, M.; Krieg, S.

    2014-10-01

    We present lattice QCD calculations of nucleon electromagnetic form factors using pion masses mπ=149, 202, and 254 MeV and an action with clover-improved Wilson quarks coupled to smeared gauge fields, as used by the Budapest-Marseille-Wuppertal Collaboration. Particular attention is given to the removal of the effects of excited-state contamination by calculations at three source-sink separations and the use of the summation and generalized pencil-of-function methods. The combination of a calculation at the nearly physical mass mπ=149 MeV in a large spatial volume (mπLs=4.2) and the removal of excited-state effects yields agreement with experiment for the electric and magnetic form factors GE(Q2) and GM(Q2) up to Q2=0.5 GeV2.

  15. Bottomonium spectrum at order v{sup 6} from domain-wall lattice QCD: Precise results for hyperfine splittings

    SciTech Connect

    Meinel, Stefan

    2010-12-01

    The bottomonium spectrum is computed in dynamical 2+1 flavor lattice QCD, using nonrelativistic QCD for the b quarks. The main calculations in this work are based on gauge field ensembles generated by the RBC and UKQCD Collaborations with the Iwasaki action for the gluons and a domain-wall action for the sea quarks. Lattice spacing values of approximately 0.08 fm and 0.11 fm are used, and simultaneous chiral extrapolations to the physical pion mass are performed. As a test for gluon-discretization errors, the calculations are repeated on two ensembles generated by the MILC Collaboration with the Luescher-Weisz gauge action. Gluon-discretization errors are also studied in a lattice potential model using perturbation theory for four different gauge actions. The nonperturbative lattice QCD results for the radial and orbital bottomonium energy splittings obtained from the RBC/UKQCD ensembles are found to be in excellent agreement with experiment. To get accurate results for spin splittings, the spin-dependent order-v{sup 6} terms are included in the nonrelativistic QCD action, and suitable ratios are calculated such that most of the unknown radiative corrections cancel. The cancellation of radiative corrections is verified explicitly by repeating the calculations with different values of the couplings in the nonrelativistic QCD action. Using the lattice ratios of the S-wave hyperfine and the 1P tensor splitting, and the experimental result for the 1P tensor splitting, the 1S hyperfine splitting is found to be 60.3{+-}5.5{sub stat{+-}}5.0{sub syst{+-}}2.1{sub exp} MeV, and the 2S hyperfine splitting is predicted to be 23.5{+-}4.1{sub stat{+-}}2.1{sub syst{+-}}0.8{sub exp} MeV.

  16. QCD at zero baryon density and the Polyakov loop paradox

    SciTech Connect

    Kratochvila, Slavo; Forcrand, Philippe de

    2006-06-01

    We compare the grand-canonical partition function at fixed chemical potential {mu} with the canonical partition function at fixed baryon number B, formally and by numerical simulations at {mu}=0 and B=0 with four flavors of staggered quarks. We verify that the free energy densities are equal in the thermodynamic limit, and show that they can be well described by the hadron resonance gas at TT{sub c}. Small differences between the two ensembles, for thermodynamic observables characterizing the deconfinement phase transition, vanish with increasing lattice size. These differences are solely caused by contributions of nonzero baryon density sectors, which are exponentially suppressed with increasing volume. The Polyakov loop shows a different behavior: for all temperatures and volumes, its expectation value is exactly zero in the canonical formulation, whereas it is always nonzero in the commonly used grand-canonical formulation. We clarify this paradoxical difference, and show that the nonvanishing Polyakov loop expectation value is due to contributions of nonzero triality states, which are not physical, because they give zero contribution to the partition function.

  17. A study on the optimization of finite volume effects of B K in lattice QCD by using the CUDA

    NASA Astrophysics Data System (ADS)

    Kim, Jangho; Cho, Kihyeon

    2015-07-01

    Lattice quantum chromodynamics (QCD) is the non-perturbative implementation of field theory to solve the QCD theory of quarks and gluons by using the Feynman path integral approach. We calculate the kaon CP (charge-parity) violation parameter B K generally arising in theories of physics beyond the Standard Model. Because lattice simulations are performed on finite volume lattices, the finite volume effects must be considered to exactly estimate the systematic error. The computational cost of numerical simulations may increase dramatically as the lattice spacing is decreased. Therefore, lattice QCD calculations must be optimized to account for the finite volume effects. The methodology used in this study was to develop an algorithm to parallelize the code by using a graphic processing unit (GPU) and to optimize the code to achieve as close to the theoretical peak performance as possible. The results revealed that the calculation speed of the newly-developed algorithm is significantly improved compared with that of the current algorithm for the finite volume effects.

  18. Estimate of the hadronic vacuum polarization disconnected contribution to the anomalous magnetic moment of the muon from lattice QCD

    NASA Astrophysics Data System (ADS)

    Chakraborty, Bipasha; Davies, C. T. H.; Koponen, J.; Lepage, G. P.; Peardon, M. J.; Ryan, S. M.

    2016-04-01

    The quark-line disconnected diagram is a potentially important ingredient in lattice QCD calculations of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. It is also a notoriously difficult one to evaluate. Here, for the first time, we give an estimate of this contribution based on lattice QCD results that have a statistically significant signal, albeit at one value of the lattice spacing and an unphysically heavy value of the u /d quark mass. We use HPQCD's method of determining the anomalous magnetic moment by reconstructing the Adler function from time moments of the current-current correlator at zero spatial momentum. Our results lead to a total (including u , d and s quarks) quark-line disconnected contribution to aμ of -0.15 % of the u /d hadronic vacuum polarization contribution with an uncertainty which is 1% of that contribution.

  19. Vacuum Energy, EoS, and the Gluon Condensate at Finite Baryon Density in QCD

    SciTech Connect

    Zhitnitsky, Ariel R.

    2007-02-27

    The Equation of States (EoS) plays the crucial role in all studies of neutron star properties. Still, a microscopical understanding of EoS remains largely an unresolved problem. We use 2-color QCD as a model to study the dependence of vacuum energy (gluon condensate in QCD) as function of chemical potential {mu} << {lambda}QCD where we find very strong and unexpected dependence on {mu}. We present the arguments suggesting that similar behavior may occur in 3-color QCD in the color superconducting phases. Such a study may be of importance for analysis of EoS when phenomenologically relevant parameters (within such models as MIT Bag model or NJL model) are fixed at zero density while the region of study lies at much higher densities not available for terrestrial tests.

  20. The Sequential Empirical Bayes Method: An Adaptive Constrained-Curve Fitting Algorithm for Lattice QCD

    SciTech Connect

    Ying Chen; Shao-Jing Dong; Terrence Draper; Ivan Horvath; Keh-Fei Liu; Nilmani Mathur; Sonali Tamhankar; Cidambi Srinivasan; Frank X. Lee; Jianbo Zhang

    2004-05-01

    We introduce the ''Sequential Empirical Bayes Method'', an adaptive constrained-curve fitting procedure for extracting reliable priors. These are then used in standard augmented-{chi}{sup 2} fits on separate data. This better stabilizes fits to lattice QCD overlap-fermion data at very low quark mass where a priori values are not otherwise known. Lessons learned (including caveats limiting the scope of the method) from studying artificial data are presented. As an illustration, from local-local two-point correlation functions, we obtain masses and spectral weights for ground and first-excited states of the pion, give preliminary fits for the a{sub 0} where ghost states (a quenched artifact) must be dealt with, and elaborate on the details of fits of the Roper resonance and S{sub 11}(N{sup 1/2-}) previously presented elsewhere. The data are from overlap fermions on a quenched 16{sup 3} x 28 lattice with spatial size La = 3.2 fm and pion mass as low as {approx}180 MeV.

  1. Moments of Nucleon's Parton Distribution for the Sea and Valence Quarks from Lattice QCD

    SciTech Connect

    Deka, Mridupawan; Streuer, Thomas; Doi, Takumi; Dong, Shao-Jing; Draper, Terrence; Liu, Keh-Fei; Mathur, Nilmani; Thomas, Anthony

    2009-01-01

    We extend the study of lowest moments, $$ and $$, of the parton distribution function of the nucleon to include those of the sea quarks; this entails a disconnected insertion calculation in lattice QCD. This is carried out on a $16^3 \\times 24$ quenched lattice with Wilson fermion. The quark loops are calculated with $Z_2$ noise vectors and unbiased subtractions, and multiple nucleon sources are employed to reduce the statistical errors. We obtain 5$\\sigma$ signals for $$ for the $u,d,$ and $s$ quarks, but $$ is consistent with zero within errors. We provide results for both the connected and disconnected insertions. The perturbatively renormalized $$ for the strange quark at $\\mu = 2$ GeV is $_{s+\\bar{s}} = 0.027 \\pm 0.006$ which is consistent with the experimental result. The ratio of $$ for $s$ vs. $u/d$ in the disconnected insertion with quark loops is calculated to be $0.88 \\pm 0.07$. This is about twice as large as the phenomenologically fitted $\\displays

  2. Improved stochastic estimation of quark propagation with Laplacian Heaviside smearing in lattice QCD

    SciTech Connect

    Morningstar, C.; Lenkner, D.; Wong, C. H.; Bulava, J.; Foley, J.; Juge, K. J.; Peardon, M.

    2011-06-01

    A new method of stochastically estimating the low-lying effects of quark propagation is proposed which allows accurate determinations of temporal correlations of single-hadron and multihadron operators in lattice QCD. The method is well suited for calculations in large volumes. Contributions involving quark propagation connecting hadron sink operators at the same final time can be handled in a straightforward manner, even for a large number of final time slices. The method exploits Laplacian Heaviside (LapH) smearing. Z{sub N} noise is introduced in a novel way, and variance reduction is achieved using judiciously-chosen noise-dilution projectors. The method is tested using isoscalar mesons in the scalar, pseudoscalar, and vector channels, and using the two-pion system of total isospin I=0, 1, 2 on large anisotropic 24{sup 3}x128 lattices with spatial spacing a{sub s}{approx}0.12 fm and temporal spacing a{sub t}{approx}0.034 fm for pion masses m{sub {pi}}{approx_equal}390 and 240 MeV.

  3. The Flavor Structure of the Excited Baryon Spectra from Lattice QCD

    SciTech Connect

    Edwards, Robert G.; Mathur, Nilmani; Richards, David G.; Wallace, Stephen J

    2013-03-01

    Excited state spectra are calculated using lattice QCD for baryons that can be formed from $u$, $d$ and $s$ quarks, namely the $N$, $\\Delta$, $\\Lambda$, $\\Sigma$, $\\Xi$ and $\\Omega$ families of baryons. Baryonic operators are constructed from continuum operators that transform as irreducible representations of SU(3)$_F$ symmetry for flavor, SU(4) symmetry for Dirac spins of quarks and O(3) symmetry for orbital angular momenta. Covariant derivatives are used to realize orbital angular momenta. Using the operators, we calculate matrices of correlation functions in order to extract excited states. The resulting lattice spectra have bands of baryonic states with well-defined total spins up to $J=7/2$. Each state can be assigned a dominant flavor symmetry and the counting of states of each flavor and spin reflects $SU(6) \\times O(3)$ symmetry for the lowest negative-parity and positive-parity bands. States with strong hybrid content are identified through the dominance of chromo-magnetic operators.

  4. Direct Evaluation of the Quark Content of Nucleons from Lattice QCD at the Physical Point

    NASA Astrophysics Data System (ADS)

    Abdel-Rehim, A.; Alexandrou, C.; Constantinou, M.; Hadjiyiannakou, K.; Jansen, K.; Kallidonis, Ch.; Koutsou, G.; Avilés-Casco, A. Vaquero

    2016-06-01

    We evaluate the light, strange, and charm scalar content of the nucleon using one lattice QCD ensemble generated with two degenerate light quarks with mass fixed to their physical value. We use improved techniques to evaluate the disconnected quark loops to sufficient accuracy to determine the strange and charm nucleon σ terms in addition to the light quark content σπ N. We find σπ N=37.2 (2.6 )(4.7 2.9 ) MeV , σs=41.1 (8.2 )(7.8 5.8 ) MeV , and σc=79 (21 )(12 8 ) MeV , where the first error is statistical and the second is the systematic error due to the determination of the lattice spacing, the assessment of finite volume, and residual excited state effects.

  5. Low-lying {Lambda} baryons with spin 1/2 in two-flavor lattice QCD

    SciTech Connect

    Takahashi, Toru T.; Oka, Makoto

    2010-02-01

    Low-lying {Lambda} baryons with spin 1/2 are analyzed in full (unquenched) lattice QCD. We construct 2x2 cross correlators from flavor SU(3) octet and singlet baryon operators, and diagonalize them so as to extract information of two low-lying states for each parity. The two-flavor CP-PACS gauge configurations are used, which are generated in the renormalization-group improved gauge action and the O(a)-improved quark action. Three different {beta}'s, {beta}=1.80, 1.95, and 2.10, are employed, whose corresponding lattice spacings are a=0.2150, 0.1555, and 0.1076 fm. For each cutoff, we use four hopping parameters, ({kappa}{sub val},{kappa}{sub sea}), which correspond to the pion masses ranging about from 500 MeV to 1.1 GeV. Results indicate that there are two negative-parity {Lambda} states nearly degenerate at around 1.6 GeV, while no state as low as {Lambda}(1405) is observed. By decomposing the flavor components of each state, we find that the lowest (1st-excited) negative-parity state is dominated by flavor-singlet (flavor-octet) component. We also discuss meson-baryon components of each state, which has drawn considerable attention in the context of multiquark pictures of {Lambda}(1405).

  6. Evolution of probability densities in stochastic coupled map lattices

    NASA Astrophysics Data System (ADS)

    Losson, Jérôme; Mackey, Michael C.

    1995-08-01

    This paper describes the statistical properties of coupled map lattices subjected to the influence of stochastic perturbations. The stochastic analog of the Perron-Frobenius operator is derived for various types of noise. When the local dynamics satisfy rather mild conditions, this equation is shown to possess either stable, steady state solutions (i.e., a stable invariant density) or density limit cycles. Convergence of the phase space densities to these limit cycle solutions explains the nonstationary behavior of statistical quantifiers at equilibrium. Numerical experiments performed on various lattices of tent, logistic, and shift maps with diffusivelike interelement couplings are examined in light of these theoretical results.

  7. Isovector and isoscalar tensor charges of the nucleon from lattice QCD

    DOE PAGESBeta

    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

  8. Isovector and isoscalar tensor charges of the nucleon from lattice QCD

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Cohen, Saul D.; Gupta, Rajan; Joseph, Anosh; Lin, Huey-Wen; Yoon, Boram; Precision Neutron Decay Matrix Elements Pndme Collaboration

    2015-11-01

    We present results for the isovector and flavor diagonal tensor charges gTu -d, gTu , gTd , and gTs 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. 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 gTu -d=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 gTu=0.774 (66 ) , gTd=-0.233 (28 ) and gTu +d=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 gTs=0.008 (9 ) in the continuum limit.

  9. Lattice QCD study of the Boer-Mulders effect in a pion

    NASA Astrophysics Data System (ADS)

    Engelhardt, M.; Hägler, P.; Musch, B.; Negele, J.; Schäfer, A.

    2016-03-01

    The three-dimensional momenta of quarks inside a hadron are encoded in transverse momentum-dependent parton distribution functions (TMDs). This work presents an exploratory lattice QCD study of a TMD observable in the pion describing the Boer-Mulders effect, which is related to polarized quark transverse momentum in an unpolarized hadron. The primary goal is to gain insight into the behavior of TMDs as a function of a Collins-Soper evolution parameter, ζ ^, which quantifies the rapidity difference between the hadron momentum and a vector describing the trajectory of the struck quark, e.g., in a semi-inclusive deep-inelastic scattering (SIDIS) process. The lattice calculation, performed at the pion mass mπ=518 MeV , utilizes a definition of TMDs via hadronic matrix elements of a quark bilocal operator with a staple-shaped gauge connection; in this context, the evolution parameter is related to the staple direction. By parametrizing the aforementioned matrix elements in terms of invariant amplitudes, the problem can be cast in a Lorentz frame suited for the lattice calculation. Aided by the lower mass of the pion, compared to the nucleon studied previously, the present investigation of pion TMD observables constitutes an important step towards the quantitative study of the physically important regime of large relative rapidity where the dependence on ζ ^ appears to approach a limit. Although matching to perturbative evolution equations in ζ ^ is not yet available, extrapolations based on Ansätze containing inverse powers of ζ ^ yield stable results with an uncertainty as low as 20%, and both upper and lower bounds for the asymptotics are obtained. In passing, the similarity between the Boer-Mulders effects extracted in the pion and the nucleon is noted.

  10. Solution of an associating lattice-gas model with density anomaly on a Husimi lattice

    NASA Astrophysics Data System (ADS)

    Oliveira, Tiago J.; Stilck, Jürgen F.; Barbosa, Marco Aurélio A.

    2010-11-01

    We study a model of a lattice gas with orientational degrees of freedom which resemble the formation of hydrogen bonds between the molecules. In this model, which is the simplified version of the Henriques-Barbosa model, no distinction is made between donors and acceptors in the bonding arms. We solve the model in the grand-canonical ensemble on a Husimi lattice built with hexagonal plaquettes with a central site. The ground state of the model, which was originally defined on the triangular lattice, is exactly reproduced by the solution on this Husimi lattice. In the phase diagram, one gas and two liquid [high density liquid (HDL) and low density liquid (LDL)] phases are present. All phase transitions (GAS-LDL, GAS-HDL, and LDL-HDL) are discontinuous, and the three phases coexist at a triple point. A line of temperatures of maximum density in the isobars is found in the metastable GAS phase, as well as another line of temperatures of minimum density appears in the LDL phase, part of it in the stable region and another in the metastable region of this phase. These findings are at variance with simulational results for the same model on the triangular lattice, which suggested a phase diagram with two critical points. However, our results show very good quantitative agreement with the simulations, both for the coexistence loci and the densities of particles and of hydrogen bonds. We discuss the comparison of the simulations with our results.

  11. B-meson decay constants from improved lattice nonrelativistic QCD with physical u, d, s, and c quarks.

    PubMed

    Dowdall, R J; Davies, C T H; Horgan, R R; Monahan, C J; Shigemitsu, J

    2013-05-31

    We present the first lattice QCD calculation of the decay constants f(B) and f(B(s)) with physical light quark masses. We use configurations generated by the MILC Collaboration including the effect of u, d, s, and c highly improved staggered quarks in the sea at three lattice spacings and with three u/d quark mass values going down to the physical value. We use improved nonrelativistic QCD (NRQCD) for the valence b quarks. Our results are f(B)=0.186(4) GeV, f(B(s))=0.224(4) GeV, f(B(s))/f(B)=1.205(7), and M(B(s))-M(B)=85(2) MeV, superseding earlier results with NRQCD b quarks. We discuss the implications of our results for the standard model rates for B((s))→μ(+)μ(-) and B→τν. PMID:23767714

  12. Spin and charge density waves in the Lieb lattice

    NASA Astrophysics Data System (ADS)

    Gouveia, J. D.; Dias, R. G.

    2016-05-01

    We study the mean-field phase diagram of the two-dimensional (2D) Hubbard model in the Lieb lattice allowing for spin and charge density waves. Previous studies of this diagram have shown that the mean-field magnetization surprisingly deviates from the value predicted by Lieb's theorem [1] as the on-site repulsive Coulomb interaction (U) becomes smaller [2]. Here, we show that in order for Lieb's theorem to be satisfied, a more complex mean-field approach should be followed in the case of bipartite lattices or other lattices whose unit cells contain more than two types of atoms. In the case of the Lieb lattice, we show that, by allowing the system to modulate the magnetization and charge density between sublattices, the difference in the absolute values of the magnetization of the sublattices, mLieb, at half-filling, saturates at the exact value 1/2 for any value of U, as predicted by Lieb. Additionally, Lieb's relation, mLieb = 1 / 2, is verified approximately for large U, in the n ∈ [ 2 / 3 , 4 / 3 ] range. This range includes not only the ferromagnetic region of the phase diagram of the Lieb lattice (see Ref. [2]), but also the adjacent spiral regions. In fact, in this lattice, below or at half-filling, mLieb is simply the filling of the quasi-flat bands in the mean-field energy dispersion both for large and small U.

  13. Volume dependence of the long-range two-body potentials in various color channels by lattice QCD

    SciTech Connect

    Nakagawa, Y.; Toki, H.; Nakamura, A.; Saito, T.

    2008-02-01

    We study the color-dependent confining forces between two quarks by the quenched lattice simulations of Coulomb gauge QCD. The color-singlet and color-antitriplet instantaneous potentials yield attractive forces. The ratio of the string tensions obtained from them is approximately 2, and these tensions have little volume dependence. Meanwhile, the color-octet and color-sextet channels give a minor contribution to the two-quark system. We finally find that the infrared self-energy of the color-nonsinglet channels diverges in the infinite volume limit; however, the degree of the divergence on the finite lattice can be understood in terms of color factors.

  14. The Gell-Mann - Okubo Mass Relation among Baryons from Fully-Dynamical, Mixed-Action Lattice QCD

    SciTech Connect

    Konstantinos Orginos; Silas Beane; Martin Savage

    2007-10-01

    We explore the Gell-Mann - Okubo mass relation among the octet baryons using fully-dynamical, mixed-action (domain-wall on rooted-staggered) lattice QCD calculations at a lattice spacing of b {approx} 0.125 fm and pion masses of m{sub pi} {approx} 290 MeV, 350 MeV, 490 MeV and 590 MeV. Deviations from the Gell-Mann - Okubo mass relation are found to be small at each quark mass.

  15. Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD

    DOE PAGESBeta

    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

  16. Gluon propagators in maximally Abelian gauge in SU(3) lattice QCD

    NASA Astrophysics Data System (ADS)

    Gongyo, Shinya; Suganuma, Hideo

    2013-04-01

    In SU(3) lattice QCD, we study diagonal and off-diagonal gluon propagators in the maximally Abelian gauge with U(1)3×U(1)8 Landau gauge fixing. These propagators are studied both in the coordinate space and in the momentum space. The Monte Carlo simulation is performed on 164 at β=6.0 and 324 at β=5.8 and 6.0 at the quenched level. In the four-dimensional Euclidean space-time, the effective mass of diagonal gluons is estimated as Mdiag≃0.3GeV and that of off-diagonal gluons as Moff≃1GeV in the region of r=0.4-1.0fm. In the momentum space, the effective mass of diagonal gluons is estimated as Mdiag≃0.3GeV and that of off-diagonal gluons as Moff≃1GeV in the region of p<1.1GeV. The off-diagonal gluon propagator is relatively suppressed in the infrared region and seems to be finite at zero momentum, while the diagonal gluon propagator is enhanced. Furthermore, we also study the functional form of these propagators in momentum space. These propagators are well fitted by Z/(p2+m2)ν with fit parameters, Z, m, and ν in the region of p<3.0GeV. From the fit results and lattice calculations, all of the spectral functions of diagonal and off-diagonal gluons would have negative regions.

  17. Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD

    SciTech Connect

    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+-, 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 |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.

  18. tmLQCD: A program suite to simulate Wilson twisted mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Jansen, Karl; Urbach, Carsten

    2009-12-01

    We discuss a program suite for simulating Quantum Chromodynamics on a 4-dimensional space-time lattice. The basic Hybrid Monte Carlo algorithm is introduced and a number of algorithmic improvements are explained. We then discuss the implementations of these concepts as well as our parallelisation strategy in the actual simulation code. Finally, we provide a user guide to compile and run the program. Program summaryProgram title: tmLQCD Catalogue identifier: AEEH_v1_0 Program summary URL::http://cpc.cs.qub.ac.uk/summaries/AEEH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public Licence (GPL) No. of lines in distributed program, including test data, etc.: 122 768 No. of bytes in distributed program, including test data, etc.: 931 042 Distribution format: tar.gz Programming language: C and MPI Computer: any Operating system: any with a standard C compiler Has the code been vectorised or parallelised?: Yes. One or optionally any even number of processors may be used. Tested with up to 32 768 processors RAM: no typical values available Classification: 11.5 External routines: LAPACK [1] and LIME [2] library Nature of problem: Quantum Chromodynamics Solution method: Markov Chain Monte Carlo using the Hybrid Monte Carlo algorithm with mass preconditioning and multiple time scales [3]. Iterative solver for large systems of linear equations. Restrictions: Restricted to an even number of (not necessarily mass degenerate) quark flavours in the Wilson or Wilson twisted mass formulation of lattice QCD. Running time: Depending on the problem size, the architecture and the input parameters from a few minutes to weeks. References:http://www.netlib.org/lapack/. USQCD, http://usqcd.jlab.org/usqcd-docs/c-lime/. C. Urbach, K. Jansen, A. Shindler, U. Wenger, Comput. Phys. Commun. 174 (2006) 87, hep-lat/0506011.

  19. Meson-Baryon Scattering Lengths from Mixed-Action Lattice QCD

    SciTech Connect

    Beane, S; Detmold, W; Luu, T; Orginos, K; Parreno, A; Torok, A; Walker-Loud, A

    2009-06-30

    The {pi}{sup +}{Sigma}{sup +}, {pi}{sup +}{Xi}{sup 0}, K{sup +}p, K{sup +}n, {bar K}{sup 0}{Sigma}{sup +}, and {bar K}{sup 0}{Xi}{sup 0} scattering lengths are calculated in mixed-action Lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations at four light-quark masses, and at two light-quark masses on the fine MILC configurations. Heavy Baryon Chiral Perturbation Theory with two and three flavors of light quarks is used to perform the chiral extrapolations. We find no convergence for the kaon-baryon processes in the three-flavor chiral expansion. Using the two-flavor chiral expansion, we find a{sub {pi}{sup +}{Sigma}{sup +}} = -0.197 {+-} 0.017 fm, and a{sub {pi}{sup +}{Xi}{sup 0}} = -0.098 {+-} 0.017 fm, where the comprehensive error includes statistical and systematic uncertainties.

  20. Measuring the nucleon strangeness and related matrix elements using lattice QCD

    NASA Astrophysics Data System (ADS)

    Freeman, Walter

    2011-12-01

    We calculate the strange quark content of the nucleon using a novel method with the MILC lattice QCD gauge ensembles. The strangeness of the nucleon is related to the interaction cross section between dark matter and ordinary nuclear matter e.g. in detectors) in many models. Previous results for this quantity suffered from uncontrolled systematic errors and/or large statistical uncertainties. The first result using our methods was the first modern calculation of the strangeness of the nucleon with good control of systematic errors and reasonably small statistical errors, greatly reducing the uncertainty in dark matter detection cross sections. A refinement of this method allows for further reduction of statistical error. On the MILC Asqtad data, we obtain = 0.637(55)(74). The results obtained from this method are consistent with those obtained from other commonly-used methods applied to the MILC data. We also calculate the disconnected part of the pion-nucleon sigma term and the intrinsic charm of the nucleon using this method. The intrinsic charm has large statistical errors but is consistent with a perturbative calculation.

  1. K→(ππ)(I=2) decay amplitude from lattice QCD.

    PubMed

    Blum, T; Boyle, P A; Christ, N H; Garron, N; Goode, E; Izubuchi, T; Jung, C; Kelly, C; Lehner, C; Lightman, M; Liu, Q; Lytle, A T; Mawhinney, R D; Sachrajda, C T; Soni, A; Sturm, C

    2012-04-01

    We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A(2) for a kaon to decay into two π mesons with isospin 2. We find ReA(2)=(1.436±0.063(stat)±0.258(syst))10(-8) GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find ImA(2)=-(6.83±0.51(stat)±1.30(syst))10(-13) GeV. Moreover combining our result for ImA(2) with experimental values of ReA(2), ReA(0), and ε'/ε, we obtain the following value for the unknown ratio ImA(0)/ReA(0) within the standard model: ImA(0)/ReA(0)=-1.63(19)(stat)(20(syst)×10(-4). One consequence of these results is that the contribution from ImA(2) to the direct CP violation parameter ε' (the so-called Electroweak Penguin contribution) is Re(ε'/ε)(EWP)=-(6.52±0.49(stat)±1.24(syst))×10(-4). We explain why this calculation of A(2) represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays. PMID:22540784

  2. Resonances in coupled πK, ηK scattering from lattice QCD

    SciTech Connect

    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.

  3. Resonances in coupled πK, ηK scattering from lattice QCD

    DOE PAGESBeta

    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

  4. Singly and Doubly Charmed $J=1/2$ Baryon Spectrum from Lattice QCD

    SciTech Connect

    Liuming Liu; Lin, Huey-Wen; Orginos, Kostas; Walker-Loud, Andre

    2010-05-01

    We compute the masses of the singly and doubly charmed baryons in full QCD using the relativistic Fermilab action for the charm quark. For the light quarks we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We use the low-lying charmonium spectrum to tune our heavy-quark action and as a guide to understanding the discretization errors associated with the heavy quark. Our results are in good agreement with experiment within our systematicss, except for the spin-1/2 $\\Xi_{cc}$, for which we predict the isospin averaged mass to be $M_{\\Xi_{cc}} = 3665 \\pm17 \\pm14\\, {}^{+0}_{-35}$~{MeV} (here the first uncertainty is statistical, the second systematic and the third an estimate of lattice discretization errors). In addition, we predict the splitting of the (isospin averaged) spin-1/2 $\\O_{cc}$ with the $\\Xi_{cc}$ to be $M_{\\O_{cc}} - M_{\\Xi_{cc}} = 98 \\pm9 \\pm22$~{MeV} (in this mass splitting, the leading discretization errors cancel). This corresponds to a prediction of $M_{\\O_{cc}} = 3763\\pm9\\pm44\\, {}^{+0}_{-35}$~{MeV}.

  5. QCD

    NASA Astrophysics Data System (ADS)

    Fleming, Sean

    In this talk I review recent experimental and theoretical results in QCD. Since the topic is too vast to cover within given time constraints I choose to highlight some of the subjects that I find particularly exciting. On the experimental side I focus on measurements made at the Tevatron. Specifically jet production rates, and the cross section for B meson production. In addition I discuss an interesting measurement made by the Belle collaboration of double exclusive charmonium production. On the theory side I quickly review recent advances in computing hadronic cross sections at subleading order in perturbation theory. I then move on to soft-collinear effective theory. After a lightning review of the formalism I discuss recently published results on color-suppressed B → D decays.

  6. Isovector and isoscalar tensor charges of the nucleon from lattice QCD

    SciTech Connect

    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. 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.

  7. The Bayesian reconstruction of the in-medium heavy quark potential from lattice QCD and its stability

    NASA Astrophysics Data System (ADS)

    Burnier, Yannis; Kaczmarek, Olaf; Rothkopf, Alexander

    2016-01-01

    We report recent results of a non-perturbative determination of the static heavy-quark potential in quenched and dynamical lattice QCD at finite temperature. The real and imaginary part of this complex quantity are extracted from the spectral function of Wilson line correlators in Coulomb gauge. To obtain spectral information from Euclidean time numerical data, our study relies on a novel Bayesian prescription that differs from the Maximum Entropy Method. We perform simulations on quenched 323 × Nτ (β = 7.0, ξ = 3.5) lattices with Nτ = 24, …, 96, which cover 839MeV ≥ T ≥ 210MeV. To investigate the potential in a quark-gluon plasma with light u,d and s quarks we utilize Nf = 2 + 1 ASQTAD lattices with ml = ms/20 by the HotQCD collaboration, giving access to temperatures between 286MeV ≥ T ≥ 148MeV. The real part of the potential exhibits a clean transition from a linear, confining behavior in the hadronic phase to a Debye screened form above deconfinement. Interestingly its values lie close to the color singlet free energies in Coulomb gauge at all temperatures. We estimate the imaginary part on quenched lattices and find that it is of the same order of magnitude as in hard-thermal loop perturbation theory. From among all the systematic checks carried out in our study, we discuss explicitly the dependence of the result on the default model and the number of datapoints.

  8. Calculation of the heavy-hadron axial couplings g1, g2, and g3 using lattice QCD

    SciTech Connect

    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.

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

    SciTech Connect

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

    2007-06-01

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

  10. Nucleon electromagnetic form factors from lattice QCD using 2+1 flavor domain wall fermions on fine lattices and chiral perturbation theory

    SciTech Connect

    Syritsyn, S. N.; Bratt, J. D.; Lin, M. F.; Meyer, H. B.; Negele, J. W.; Pochinsky, A. V.; Procura, M.; Engelhardt, M.; Haegler, Ph.; Hemmert, T. R.; Schroers, W.

    2010-02-01

    We present a high-statistics calculation of nucleon electromagnetic form factors in N{sub f}=2+1 lattice QCD using domain wall quarks on fine lattices, to attain a new level of precision in systematic and statistical errors. Our calculations use 32{sup 3}x64 lattices with lattice spacing a=0.084 fm for pion masses of 297, 355, and 403 MeV, and we perform an overdetermined analysis using on the order of 3600 to 7000 measurements to calculate nucleon electric and magnetic form factors up to Q{sup 2{approx_equal}}1.05 GeV{sup 2}. Results are shown to be consistent with those obtained using valence domain wall quarks with improved staggered sea quarks, and using coarse domain wall lattices. We determine the isovector Dirac radius r{sub 1}{sup v}, Pauli radius r{sub 2}{sup v} and anomalous magnetic moment {kappa}{sub v}. We also determine connected contributions to the corresponding isoscalar observables. We extrapolate these observables to the physical pion mass using two different formulations of two-flavor chiral effective field theory at one loop: the heavy baryon small scale expansion and covariant baryon chiral perturbation theory. The isovector results and the connected contributions to the isoscalar results are compared with experiment, and the need for calculations at smaller pion masses is discussed.

  11. First principles calculations of nucleon and pion form factors: understanding the building blocks of nuclear matter from lattice QCD

    SciTech Connect

    Constantia Alexandrou; Bojan Bistrovic; Robert Edwards; P de Forcrand; George Fleming; Philipp Haegler; John Negele; Konstantinos Orginos; Andrew Pochinsky; Dru Renner; David Richards; Wolfram Schroers; Antonios Tsapalis

    2005-10-01

    Lattice QCD is an essential complement to the current and anticipated DOE-supported experimental program in hadronic physics. In this poster we address several key questions central to our understanding of the building blocks of nuclear matter, nucleons and pions. Firstly, we describe progress at computing the electromagnetic form factors of the nucleon, describing the distribution of charge and current, before considering the role played by the strange quarks. We then describe the study of transition form factors to the Delta resonance. Finally, we present recent work to determine the pion form factor, complementary to the current JLab experimental determination and providing insight into the approach to asymptotic freedom.

  12. Coupled ππ, KK¯ scattering in P-wave and the ρ resonance from lattice QCD

    DOE PAGESBeta

    Wilson, David J.; Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.

    2015-11-02

    In this study, we determine elastic and coupled-channel amplitudes for isospin-1 meson-meson scattering inmore » $P$-wave, by calculating correlation functions using lattice QCD with light quark masses such that $$m_\\pi = 236$$ MeV in a cubic volume of $$\\sim (4 \\,\\mathrm{fm})^3$$. Variational analyses of large matrices of correlation functions computed using operator constructions resembling $$\\pi\\pi$$, $$K\\overline{K}$$ and $$q\\bar{q}$$, in several moving frames and several lattice irreducible representations, leads to discrete energy spectra from which scattering amplitudes are extracted. In the elastic $$\\pi\\pi$$ scattering region we obtain a detailed energy-dependence for the phase-shift, corresponding to a $$\\rho$$ resonance, and we extend the analysis into the coupled-channel $$K\\overline{K}$$ region for the first time, finding a small coupling between the channels.« less

  13. Mixing and CP-violation in K and B-mesons: A lattice QCD point of view

    NASA Astrophysics Data System (ADS)

    Lusignoli, Maurizio; Maiani, Luciano; Martinelli, Guido; Reina, Laura

    1991-07-01

    The neutral K-antineutral K and neutral B-antineutral B mixing is analyzed on the basis of experimental results and theoretical lattice determination of the relevant matrix elements. A top mass larger than 140 GeV and f(sub B) equal or greater than 200 MeV is found. These results suggest a Charge conjugation and Space inversion (CP) violating asymmetry in B decays to J/psi + K(sub S) much larger than previously estimated. The corresponding theoretical prediction for epsilon'/epsilon for which rather large experimental and theoretical uncertainties still exist is reported. The basic definitions and formulae for the calculation of epsilon, R(sub d) and epsilon(prime) are given. The determination of the real angles from semileptonic data is discussed. The calculation of the Wilson coefficients is illustrated. Short distance Quantum Chromodynamics (QCD) corrections are evaluated. The B parameters, from lattice calculations, are presented.

  14. Exact maps in density functional theory for lattice models

    NASA Astrophysics Data System (ADS)

    Dimitrov, Tanja; Appel, Heiko; Fuks, Johanna I.; Rubio, Angel

    2016-08-01

    In the present work, we employ exact diagonalization for model systems on a real-space lattice to explicitly construct the exact density-to-potential and graphically illustrate the complete exact density-to-wavefunction map that underly the Hohenberg–Kohn theorem in density functional theory. Having the explicit wavefunction-to-density map at hand, we are able to construct arbitrary observables as functionals of the ground-state density. We analyze the density-to-potential map as the distance between the fragments of a system increases and the correlation in the system grows. We observe a feature that gradually develops in the density-to-potential map as well as in the density-to-wavefunction map. This feature is inherited by arbitrary expectation values as functional of the ground-state density. We explicitly show the excited-state energies, the excited-state densities, and the correlation entropy as functionals of the ground-state density. All of them show this exact feature that sharpens as the coupling of the fragments decreases and the correlation grows. We denominate this feature as intra-system steepening and discuss how it relates to the well-known inter-system derivative discontinuity. The inter-system derivative discontinuity is an exact concept for coupled subsystems with degenerate ground state. However, the coupling between subsystems as in charge transfer processes can lift the degeneracy. An important conclusion is that for such systems with a near-degenerate ground state, the corresponding cut along the particle number N of the exact density functionals is differentiable with a well-defined gradient near integer particle number.

  15. Tests of QCD at HERA: determination of the gluon density

    SciTech Connect

    Repond, J.

    1996-12-31

    An overview is given of the various methods available to the colliding beam experiments at HERA to determine the gluon density of the proton. The article includes a description of fits to the structure function F{sub 2}, of studies of dijet and open charm production in deep inelastic scattering, of elastic and inelastic {psi} photoproduction, and of inclusive diffractive scattering. 13 refs., 8 figs.

  16. B →π ℓν at zero recoil from lattice QCD with physical u /d quarks

    NASA Astrophysics Data System (ADS)

    Colquhoun, B.; Dowdall, R. J.; Koponen, J.; Davies, C. T. H.; Lepage, G. P.

    2016-02-01

    The exclusive semileptonic decay B →π ℓν is a key process for the determination of the Cabibbo-Kobayashi-Maskawa matrix element Vu b from the comparison of experimental rates as a function of q2 with theoretically determined form factors. The sensitivity of the form factors to the u /d quark mass has meant significant systematic uncertainties in lattice QCD calculations at unphysically heavy pion masses. Here, we give the first lattice QCD calculations of this process for u /d quark masses going down to their physical values, calculating the f0 form factor at zero recoil to 3%. We are able to resolve a long-standing controversy by showing that the soft-pion theorem result f0(qmax2)=fB/fπ does hold as mπ→0 . We use the highly improved staggered quark formalism for the light quarks and show that staggered chiral perturbation theory for the mπ dependence is almost identical to continuum chiral perturbation theory for f0, fB, and fπ. We also give results for other processes such as Bs→K ℓν .

  17. Radiative improvement of the lattice nonrelativistic QCD action using the background field method with applications to quarkonium spectroscopy

    NASA Astrophysics Data System (ADS)

    Hammant, T. C.; Hart, A. G.; von Hippel, G. M.; Horgan, R. R.; Monahan, C. J.

    2013-07-01

    We apply the background field (BF) method to nonrelativistic QCD (NRQCD) on the lattice in order to determine the one-loop radiative corrections to the coefficients of the NRQCD action in a manifestly gauge-covariant manner by matching the NRQCD prediction for particular on-shell processes with those of relativistic continuum QCD. We explain how the BF method is implemented in automated perturbation theory and discuss the technique for matching the relativistic and nonrelativistic theories. We compute the one-loop radiative corrections to the σ·B and Darwin terms for the NRQCD action currently used in simulations, as well as the one-loop coefficients of the spin-dependent O(α2) four-fermion contact terms. The effect of the corrections on the hyperfine splitting of bottomonium is estimated using earlier simulation results [A. Gray et al., Phys. Rev. D 72, 094507 (2005)]; the corrected lattice prediction is found to be in agreement with experiment. Agreement of the hyperfine splitting of bottomonium and the B-meson system is confirmed by recent simulation studies [R. J. Dowdall et al., Phys. Rev. D 85, 054509 (2012); Phys. Rev. D 86, 094510 (2012)]. which include our NRQCD radiative corrections for the first time.

  18. Radiative transitions in charm-strange meson from Nf = 2 twisted mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Li, Ning; Wu, Ya-Jie

    2016-07-01

    We present an exploratory study on the radiative transition for the charm-strange meson: Ds∗→ D sγ using Nf = 2 twisted mass lattice quantum chromodynamics gauge configurations. The form factor for Ds meson is also determined. The simulation is performed on lattices with lattice spacings a = 0.067 fm and lattice size 323 × 64, and a = 0.085 fm and lattice size 243 × 48, respectively. Our numerical results for radiative decay width and the experimental data overlap within the margin of error.

  19. B → Dℓν form factors at nonzero recoil and |Vcb| from 2+1-flavor lattice QCD

    DOE PAGESBeta

    Bailey, Jon A.

    2015-08-10

    We present the first unquenched lattice-QCD calculation of the hadronic form factors for the exclusive decay B¯→Dℓν¯ at nonzero recoil. We carry out numerical simulations on 14 ensembles of gauge-field configurations generated with 2+1 flavors of asqtad-improved staggered sea quarks. The ensembles encompass a wide range of lattice spacings (approximately 0.045 to 0.12 fm) and ratios of light (up and down) to strange sea-quark masses ranging from 0.05 to 0.4. For the b and c valence quarks we use improved Wilson fermions with the Fermilab interpretation, while for the light valence quarks we use asqtad-improved staggered fermions. We extrapolate ourmore » results to the physical point using rooted staggered heavy-light meson chiral perturbation theory. We then parametrize the form factors and extend them to the full kinematic range using model-independent functions based on analyticity and unitarity. We present our final results for f+(q2) and f0(q2), including statistical and systematic errors, as coefficients of a series in the variable z and the covariance matrix between these coefficients. We then fit the lattice form-factor data jointly with the experimentally measured differential decay rate from BABAR to determine the CKM matrix element, |Vcb|=(39.6 ± 1.7QCD+exp ± 0.2QED) × 10–3. As a byproduct of the joint fit we obtain the form factors with improved precision at large recoil. In conclusion, we use them to update our calculation of the ratio R(D) in the Standard Model, which yields R(D)=0.299(11).« less

  20. Hubbard operator density functional theory for Fermionic lattice models

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengqian; Marianetti, Chris

    We formulate an effective action as a functional of Hubbard operator densities whose stationary point delivers all local static information of the interacting lattice model. Using the variational principle, we get a self-consistent equation for Hubbard operator densities. The computational cost of our approach is set by diagonalizing the local Fock space. We apply our method to the one and two band Hubbard model (including crystal field and on-site exchange) in infinite dimensions where the exact solution is known. Excellent agreement is obtained for the one-band model. In the two-band model, good agreement is obtained in the metallic region of the phase diagram in addition to the metal-insulator transition. While our approach does not address frequency dependent observables, it has a negligible computational cost as compared to dynamical mean field theory and could be highly applicable in the context total energies of strongly correlated materials and molecules.

  1. Numerical study of QCD phase diagram at high temperature and density by a histogram method

    NASA Astrophysics Data System (ADS)

    Ejiri, Shinji; Aoki, Sinya; Hatsuda, Tetsuo; Kanaya, Kazuyuki; Nakagawa, Yoshiyuki; Ohno, Hiroshi; Saito, Hana; Umeda, Takashi

    2012-12-01

    We study the QCD phase structure at high temperature and density adopting a histogram method. Because the quark determinant is complex at finite density, the Monte-Carlo method cannot be applied directly. We use a reweighting method and try to solve the problems which arise in the reweighting method, i.e. the sign problem and the overlap problem. We discuss the chemical potential dependence of the probability distribution function in the heavy quark mass region and examine the applicability of the approach in the light quark region.

  2. Finite density phase transition of QCD with N{sub f}=4 and N{sub f}=2 using canonical ensemble method

    SciTech Connect

    Li Anyi; Alexandru, Andrei; Liu, Keh-Fei; Meng Xiangfei

    2010-09-01

    In a progress toward searching for the QCD critical point, we study the finite density phase transition of N{sub f}=4 and 2 lattice QCD at finite temperature with the canonical ensemble approach. We develop a winding number expansion method to accurately project out the particle number from the fermion determinant which greatly extends the applicable range of baryon number sectors to make the study feasible. Our lattice simulation was carried out with the clover fermions and improved gauge action. For a given temperature, we calculate the baryon-chemical potential from the canonical approach to look for the mixed phase as a signal for the first-order phase transition. In the case of N{sub f}=4, we observe an 'S-shape' structure in the chemical potential-density plane due to the surface tension of the mixed phase in a finite volume which is a signal for the first-order phase transition. We use the Maxwell construction to determine the phase boundaries for three temperatures below T{sub c}. The intersecting point of the two extrapolated boundaries turns out to be at the expected first-order transition point at T{sub c} with {mu}=0. This serves as a check for our method of identifying the critical point. We also studied the N{sub f}=2 case, but do not see a signal of the mixed phase for temperature as low as 0.83T{sub c}.

  3. B -meson decay constants from 2 +1 -flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

    NASA Astrophysics Data System (ADS)

    Christ, N. H.; Flynn, J. M.; Izubuchi, T.; Kawanai, T.; Lehner, C.; Soni, A.; van de Water, R. S.; Witzel, O.; Rbc; Ukqcd Collaborations

    2015-03-01

    We calculate the B -meson decay constants fB , fBs , and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈0.11 , 0.086 fm with unitary pion masses as light as Mπ≈290 MeV ; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O (αsa ) . We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain fB0=199.5 (12.6 ) MeV , fB+=195.6 (14.9 ) MeV , fBs=235.4 (12.2 ) MeV , fBs/fB0=1.197 (50 ) , and fBs/fB+=1.223 (71 ) , where the errors are statistical and total systematic added in quadrature. These results are in good agreement with other published results and provide an important independent cross-check of other three-flavor determinations of B -meson decay constants using staggered light quarks.

  4. Lattice QCD calculation of form factors describing the rare decays B→K*ℓ+ℓ- and Bs→ϕℓ+ℓ-

    NASA Astrophysics Data System (ADS)

    Horgan, Ronald R.; Liu, Zhaofeng; Meinel, Stefan; Wingate, Matthew

    2014-05-01

    The rare decays B0→K*0μ+μ- and Bs→ϕμ+μ- are now being observed with enough precision to test Standard Model predictions. A full understanding of these decays requires accurate determinations of the corresponding hadronic form factors. Here we present results of lattice QCD calculations of the B→K* and Bs→ϕ form factors. We also determine the form factors relevant for the decays Bs→K*ℓν and Bs→K¯*0ℓ+ℓ-. We use full-QCD configurations including 2+1 flavors of sea quarks using an improved staggered action, and we employ lattice nonrelativistic QCD to describe the bottom quark.

  5. Quarkyonic Matter and the Phase Diagram of QCD

    SciTech Connect

    McLerran,L.

    2008-05-15

    Quarkyonic matter is a new phase of QCD at finite temperature and density which is distinct from the confined and de-confined phases. Its existence is unambiguously argued in the large numbers of colors limit, N{sub c} {yields} {infinity}, of QCD. Hints of its existence for QCD, N{sub c} = 3, are shown in lattice Monte-Carlo data and in heavy ion experiments.

  6. I = 1 and I = 2 π-π scattering phase shifts from Nf = 2 + 1 lattice QCD

    NASA Astrophysics Data System (ADS)

    Bulava, John; Fahy, Brendan; Hörz, Ben; Juge, Keisuke J.; Morningstar, Colin; Wong, Chik Him

    2016-09-01

    The I = 1 p-wave and I = 2 s-wave elastic π-π scattering amplitudes are calculated from a first-principles lattice QCD simulation using a single ensemble of gauge field configurations with Nf = 2 + 1 dynamical flavors of anisotropic clover-improved Wilson fermions. This ensemble has a large spatial volume V =(3.7 fm) 3, pion mass mπ = 230 MeV, and spatial lattice spacing as = 0.11 fm. Calculation of the necessary temporal correlation matrices is efficiently performed using the stochastic LapH method, while the large volume enables an improved energy resolution compared to previous work. For this single ensemble we obtain mρ /mπ = 3.350 (24), gρππ = 5.99 (26), and a clear signal for the I = 2 s-wave. The success of the stochastic LapH method in this proof-of-principle large-volume calculation paves the way for quantitative study of the lattice spacing effects and quark mass dependence of scattering amplitudes using state-of-the-art ensembles.

  7. Up, down, strange and charm quark masses with Nf=2+1+1 twisted mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Carrasco, N.; Deuzeman, A.; Dimopoulos, P.; Frezzotti, R.; Giménez, V.; Herdoiza, G.; Lami, P.; Lubicz, V.; Palao, D.; Picca, E.; Reker, S.; Riggio, L.; Rossi, G. C.; Sanfilippo, F.; Scorzato, L.; Simula, S.; Tarantino, C.; Urbach, C.; Wenger, U.

    2014-10-01

    We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2+1+1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210-450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI‧-MOM method. The results for the quark masses converted to the MSbar scheme are: mud(2 GeV)=3.70(17) MeV, ms(2 GeV)=99.6(4.3) MeV and mc(mc)=1.348(46) GeV. We obtain also the quark mass ratios ms/mud=26.66(32) and mc/ms=11.62(16). By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md=0.470(56), leading to mu=2.36(24) MeV and md=5.03(26) MeV.

  8. Charge transport and vector meson dissociation across the thermal phase transition in lattice QCD with two light quark flavors

    NASA Astrophysics Data System (ADS)

    Brandt, Bastian B.; Francis, Anthony; Jäger, Benjamin; Meyer, Harvey B.

    2016-03-01

    We compute and analyze correlation functions in the isovector vector channel at vanishing spatial momentum across the deconfinement phase transition in lattice QCD. The simulations are carried out at temperatures T /Tc=0.156 , 0.8, 1.0, 1.25 and 1.67 with Tc≃203 MeV for two flavors of Wilson-Clover fermions with a zero-temperature pion mass of ≃270 MeV . Exploiting exact sum rules and applying a phenomenologically motivated Ansatz allows us to determine the spectral function ρ (ω ,T ) via a fit to the lattice correlation function data. From these results we estimate the electrical conductivity across the deconfinement phase transition via a Kubo formula and find evidence for the dissociation of the ρ meson by resolving its spectral weight at the available temperatures. We also apply the Backus-Gilbert method as a model-independent approach to this problem. At any given frequency, it yields a local weighted average of the true spectral function. We use this method to compare kinetic theory predictions and previously published phenomenological spectral functions to our lattice study.

  9. Mixing and CP-violation in K and B-mesons: A lattice QCD point of view

    NASA Astrophysics Data System (ADS)

    Lusignoli, Maurizio; Maiani, Luciano; Martinelli, Guido; Reina, Laura

    1991-03-01

    The neutral K/antineutral K and the neutral B/antineutral B mixing is analyzed on the basis of recent experimental results and theoretical lattice determination of matrix elements. A top mass larger than 130 GeV is found. The value of f(sub B) equal to or greater than 200 MeV, as suggested by lattice calculations, implies a charge conjugation and space inversion violating asymmetry in B decays to J/psi + K(sub s) decays that are much larger than previously estimated. The corresponding theoretical prediction for epsilon(prime)/epsilon is reported. The basic definitions and formulae for the calculations of epsilon, x(sub d) and epsilon(prime) are given. The determination of the real angles from semileptonic data are discussed. The calculation of the relevant Wilson coefficient is illustrated and short distance Quantum Chromodynamics (QCD) corrections are evaluated. The B parameters, which can be derived from lattice calculations, are presented. Asumptions for the B parameters and the numerical analysis are illustrated.

  10. XXIVth International Symposium on Lattice Field Theory

    NASA Astrophysics Data System (ADS)

    2006-12-01

    Lattice 2006, the XXIV International Symposium on Lattice Field Theory, was held from July 23-28, 2006 at the Starr Pass Hotel near Tucson, Arizona, USA, hosted by the University of Arizona Physics Department. The scientific program contained 25 plenary session talks and 193 parallel session contributions (talks and posters). Topics in lattice QCD included: hadron spectroscopy; hadronic interactions and structure; algorithms, machines, and networks; chiral symmetry; QCD confinement and topology; quark masses, gauge couplings, and renormalization; electroweak decays and mixing; high temperature and density; and theoretical developments. Topics beyond QCD included large Nc, Higgs, SUSY, gravity, and strings.

  11. A model for QCD at high density and large quark mass

    SciTech Connect

    De Pietri, Roberto; Feo, Alessandra; Seiler, Erhard; Stamatescu, Ion-Olimpiu

    2007-12-01

    We study the high density region of QCD within an effective model obtained in the frame of the hopping parameter expansion and choosing Polyakov-type loops as the main dynamical variables representing the fermionic matter. To get a first idea of the phase structure, the model is analyzed in strong coupling expansion and using a mean field approximation. In numerical simulations, the model still shows the so-called sign problem, a difficulty peculiar to nonzero chemical potential, but it permits the development of algorithms which ensure a good overlap of the Monte Carlo ensemble with the true one. We review the main features of the model and present calculations concerning the dependence of various observables on the chemical potential and on the temperature, in particular, of the charge density and the diquark susceptibility, which may be used to characterize the various phases expected at high baryonic density. We obtain in this way information about the phase structure of the model and the corresponding phase transitions and crossover regions, which can be considered as hints for the behavior of nonzero density QCD.

  12. Nature of Roberge-Weiss transition endpoints for heavy quarks in Nf=2 lattice QCD with Wilson fermions

    NASA Astrophysics Data System (ADS)

    Wu, Liang-Kai; Meng, Xiang-Fei

    2014-11-01

    The phase structure of QCD with imaginary chemical potential provides information on the phase diagram of QCD with real chemical potential. With imaginary chemical potential i μI=i π T , previous studies show that the Roberge-Weiss (RW) transition endpoints are triple points at both large and small quark masses, and second order transition points at intermediate quark masses. The triple and second order endpoints are separated by two tricritical ones. We present simulations with Nf=2 Wilson fermions to investigate the nature of RW transition endpoints. The simulations are carried out at 8 values of the hopping parameter κ ranging from 0.020 to 0.140 on different lattice volumes. The Binder cumulant, susceptibility, and reweighted distribution of the imaginary part of the Polyakov loop are employed to determine the nature of RW transition endpoints. The simulations show that the two tricritical points are within the ranges 0.070-0.080 and 0.120-0.140, respectively.

  13. Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD

    NASA Astrophysics Data System (ADS)

    Braun-Munzinger, P.; Kalweit, A.; Redlich, K.; Stachel, J.

    2015-07-01

    We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge, strangeness and baryon number from experimental data at midrapidity of the ALICE Collaboration at CERN. The data were taken in central Pb-Pb collisions at √{sNN} = 2.76 TeV and cover one unit of rapidity. The resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature Tc ≃ 155 MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. The volume of the fireball for one unit of rapidity at Tc is found to exceed 3000 fm3. A detailed discussion on uncertainties in the temperature and volume of the fireball is presented. The results are linked to pion interferometry measurements and predictions from percolation theory.

  14. π π →π γ* amplitude and the resonant ρ →π γ* transition from lattice QCD

    NASA Astrophysics Data System (ADS)

    Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.; Hadron Spectrum Collaboration

    2016-06-01

    We present a determination of the P -wave π π →π γ⋆ transition amplitude from lattice quantum chromodynamics. Matrix elements of the vector current in a finite volume are extracted from three-point correlation functions, and from these we determine the infinite-volume amplitude using a generalization of the Lellouch-Lüscher formalism. We determine the amplitude for a range of discrete values of the π π energy and virtuality of the photon and observe the expected dynamical enhancement due to the ρ resonance. Describing the energy dependence of the amplitude, we are able to analytically continue into the complex energy plane and from the residue at the ρ pole extract the ρ →π γ⋆ transition form factor. This calculation, at mπ≈400 MeV , is the first to determine the form factor of an unstable hadron within a first principles approach to QCD.

  15. Neutral B-meson mixing from unquenched lattice QCD with domain-wall light quarks and static b quarks

    SciTech Connect

    Albertus, C.; Flynn, J. M.; Sachrajda, C. T.; Aoki, Y.; Ishikawa, T.; Boyle, P. A.; Wennekers, J.; Christ, N. H.; Dumitrescu, T. T.; Loktik, O.; Izubuchi, T.; Soni, A.; Van de Water, R. S.; Witzel, O.

    2010-07-01

    We demonstrate a method for calculating the neutral B-meson decay constants and mixing matrix elements in unquenched lattice QCD with domain-wall light quarks and static b-quarks. Our computation is performed on the '2+1' flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice spacing of a{approx_equal}0.11 fm (a{sup -1}=1.729 GeV) and a lattice spatial volume of approximately (1.8 fm){sup 3}. We simulate at three different light sea quark masses with pion masses down to approximately 430 MeV, and extrapolate to the physical quark masses using a phenomenologically-motivated fit function based on next-to-leading order heavy-light meson SU(2) chiral perturbation theory. For the b-quarks, we use an improved formulation of the Eichten-Hill action with static link-smearing to increase the signal-to-noise ratio. We also improve the heavy-light axial current used to compute the B-meson decay constant to O({alpha}{sub s}pa) using one-loop lattice perturbation theory. We present initial results for the SU(3)-breaking ratios f{sub B{sub s}}/f{sub B{sub d}} and {xi}=f{sub B{sub s{radical}}}(B{sub B{sub s}})/f{sub B{sub d{radical}}}(B{sub B{sub d}}), thereby demonstrating the viability of the method. For the ratio of decay constants, we find f{sub B{sub s}}/f{sub B{sub d}}=1.15(12) and for the ratio of mixing matrix elements, we find {xi}=1.13(12), where in both cases the errors reflect the combined statistical and systematic uncertainties, including an estimate of the size of neglected O(1/m{sub b}) effects.

  16. On the consistency of recent QCD lattice data of the baryon ground-state masses

    NASA Astrophysics Data System (ADS)

    Lutz, M. F. M.; Semke, A.

    2012-11-01

    In our recent analysis of lattice data of the BMW, LHPC and PACS-CS groups we determined a parameter set of the chiral Lagrangian that allows a simultaneous description of the baryon octet and decuplet masses as measured by those lattice groups. The results on the baryon spectrum of the HSC group were recovered accurately without their inclusion into our six parameter fit. We show that the same parameter set provides an accurate reproduction of the recent results of the QCDSF-UKQCD group probing the baryon masses at quite different quark masses. This shows a remarkable consistency amongst the different lattice simulations. With even more accurate lattice data in the near future it will become feasible to determine all low-energy parameters relevant at N3LO.

  17. $D$ semileptonic form factors and $|V_{cs(d)}|$ from 2+1 flavor lattice QCD

    SciTech Connect

    Bailey, Jon A.; Bazavov, A.; El-Khadra, A.X.; Gottlieb, Steven; Jain, R.D.; Kronfeld, A.S.; Van de Water, R.S.; Zhou, R.

    2011-11-01

    The measured partial widths of the semileptonic decays D {yields} K{ell}{nu} and D {yields} {pi}{ell}{nu} can be combined with the form factors calculated on the lattice to extract the CKM matrix elements |V{sub cs}| and |V{sub cd}|. The lattice calculations can be checked by comparing the form factor shapes from the lattice and experiment. We have generated a sizable data set by using heavy clover quarks with the Fermilab interpretation for charm and asqtad staggered light quarks on 2+1 flavor MILC ensembles with lattice spacings of approximately 0.12, 0.09, 0.06, and 0.045 fm. Preliminary fits to staggered chiral perturbation theory suggest that we can reduce the uncertainties in the form factors at q{sup 2} = 0 to below 5%.

  18. Precise MS light-quark masses from lattice QCD in the regularization invariant symmetric momentum-subtraction scheme

    SciTech Connect

    Gorbahn, Martin; Jaeger, Sebastian

    2010-12-01

    We compute the conversion factors needed to obtain the MS and renormalization-group-invariant (RGI) up, down, and strange quark masses at next-to-next-to-leading order from the corresponding parameters renormalized in the recently proposed RI/SMOM and RI/SMOM{sub {gamma}{sub {mu}} }renormalization schemes. This is important for obtaining the MS masses with the best possible precision from numerical lattice QCD simulations, because the customary RI{sup (')}/MOM scheme is afflicted with large irreducible uncertainties both on the lattice and in perturbation theory. We find that the smallness of the known one-loop matching coefficients is accompanied by even smaller two-loop contributions. From a study of residual scale dependences, we estimate the resulting perturbative uncertainty on the light-quark masses to be about 2% in the RI/SMOM scheme and about 3% in the RI/SMOM{sub {gamma}{sub {mu}} }scheme. Our conversion factors are given in fully analytic form, for general covariant gauge and renormalization point. We provide expressions for the associated anomalous dimensions.

  19. Scalar meson in dynamical and partially quenched two-flavor QCD: Lattice results and chiral loops

    SciTech Connect

    Prelovsek, S.; Dawson, C.; Izubuchi, T.; Orginos, K.; Soni, A.

    2004-11-01

    This is an exploratory study of the lightest nonsinglet scalar qq state on the lattice with two dynamical quarks. Domain wall fermions are used for both sea and valence quarks on a 16{sup 3}x32 lattice with an inverse lattice spacing of 1.7 GeV. We extract the scalar meson mass 1.58{+-}0.34 GeV from the exponential time dependence of the dynamical correlators with m{sub val}=m{sub sea} and N{sub f}=2. Since this statistical error bar from dynamical correlators is rather large, we analyze also the partially quenched lattice correlators with m{sub val}{ne}m{sub sea}. They are positive for m{sub val}{>=}m{sub sea} and negative for m{sub val}lattice correlators well. The leading unphysical contribution in partially quenched ChPT comes from the exchange of the two pseudoscalar fields and is also positive for m{sub val}{>=}m{sub sea} and negative for m{sub val}lattice correlators, the correlators are positive and exponentially falling. The resulting scalar meson mass 1.51{+-}0.19 GeV from the partially quenched correlators is consistent with the dynamical result and has an appreciably smaller error bar.

  20. A novel quark-field creation operator construction for hadronic physics in lattice QCD

    SciTech Connect

    Michael Peardon, Jozef Dudek, Robert Edwards, Huey-Wen Lin, David Richards, John Bulava, Colin Morningstar, Keisuke Juge

    2009-09-01

    A new quark-field smearing algorithm is defined which enables efficient calculations of a broad range of hadron correlation functions. The technique applies a low-rank operator to define smooth fields, that are to be used in hadron creation operators. The resulting space of smooth fields is small enough that all elements of the reduced quark propagator can be computed exactly at reasonable computational cost. Correlations between arbitrary sources, including multi-hadron operators can be computed {\\em a posteriori} without requiring new lattice Dirac operator inversions. The method is tested on realistic lattice sizes with light dynamical quarks.

  1. Two-point functions of quenched lattice QCD in Numerical Stochastic Perturbation Theory

    SciTech Connect

    Di Renzo, F.; Ilgenfritz, E.-M.; Perlt, H.; Schiller, A.; Torrero, C.

    2011-05-23

    We summarize the higher-loop perturbative computation of the ghost and gluon propagators in SU(3) Lattice Gauge Theory. Our final aim is to compare with results from lattice simulations in order to expose the genuinely non-perturbative content of the latter. By means of Numerical Stochastic Perturbation Theory we compute the ghost and gluon propagators in Landau gauge up to three and four loops. We present results in the infinite volume and a{yields}0 limits, based on a general fitting strategy.

  2. A new moving frame to extract scattering phases in lattice QCD

    SciTech Connect

    Dru Renner,Xu Feng,Karl Jansen

    2011-04-01

    We present a derivation of the finite-size formulae in a moving frame with total momentum P=(2pi/L)(e_1+e_2). These formulae allow us to calculate the S-wave and P-wave scattering phases at more energies with a fixed lattice size and thus help us to determine the resonance parameters precisely.

  3. Physical basis for constrained lattice density functional theory.

    PubMed

    Men, Yumei; Zhang, Xianren

    2012-03-28

    To study nucleation phenomena in an open system, a constrained lattice density functional theory (LDFT) method has been developed before to identify the unstable directions of grand potential functional and to stabilize nuclei by imposing a suitable constraint. In this work, we answer several questions about the method on a fundamental level, and give a firmer basis for the constrained LDFT method. First, we demonstrate that the nucleus structure and free energy barrier from a volume constraint method are equivalent to those from a surface constraint method. Then, we show that for the critical nucleus, the constrained LDFT method in fact produces a bias-free solution for both the nucleus structure and nucleation barrier. Finally, we give a physical interpretation of the Lagrange multiplier in the constraint method, which provides the generalized force to stabilize a nucleus in an open system. The Lagrange multiplier is found to consist of two parts: part I of the constraint produces an effective pressure, and part II imposes a constraint to counteract the supersaturation. PMID:22462885

  4. $$B\\to\\pi\\ell\\ell$$ Form Factors for New-Physics Searches from Lattice QCD

    DOE PAGESBeta

    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

  5. B→πll Form Factors for New Physics Searches from Lattice QCD.

    PubMed

    Bailey, Jon A; Bazavov, A; Bernard, C; Bouchard, C M; DeTar, C; Du, Daping; El-Khadra, A X; Freeland, E D; Gámiz, E; Gottlieb, Steven; Heller, U M; Kronfeld, A S; Laiho, J; Levkova, L; Liu, Yuzhi; Lunghi, E; Mackenzie, P B; Meurice, Y; Neil, E; Qiu, Si-Wei; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S; Zhou, Ran

    2015-10-01

    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]. PMID:26550717

  6. Thomas-Fermi Quark Model and Techniques to Improve Lattice QCD Calculation

    NASA Astrophysics Data System (ADS)

    Liu, Quan

    Two topics are discussed separately in this thesis. In the first part a semiclassical quark model, called the Thomas-Fermi quark model, is reviewed. After a modified approach to spin in the model is introduced, I present the calculation of the spectra of octet and decuplet baryons. The six-quark doubly strange H-dibaryon state is also investigated. In the second part, two numerical techniques which improve latice QCD calculations are covered. The first one, which we call Polynomial-Preconditioned GMRES-DR(PP-GMRESDR), is used to speed up the calculation of large systems of linear equations in LQCD. The second one, called the Polynomial-Subtraction method, is used to help reduce the noise variance of the calculations for disconnected loops in LQCD.

  7. Ghost-gluon coupling, power corrections, and {Lambda}{sub MS} from twisted-mass lattice QCD at N{sub f}=2

    SciTech Connect

    Blossier, B.; Boucaud, Ph.; Gravina, M.; Pene, O.; De soto, F.; Morenas, V.

    2010-08-01

    We present results concerning the nonperturbative evaluation of the ghost-gluon running QCD coupling constant from N{sub f}=2 twisted-mass lattice calculations. A novel method for calibrating the lattice spacing, independent of the string tension and hadron spectrum, is presented with results in agreement with previous estimates. The value of {Lambda}{sub MS} is computed from the running of the QCD coupling only after extrapolating to zero dynamical quark mass and after removing a nonperturbative operator-product expansion contribution that is assumed to be dominated by the dimension-two gluon condensate. The effect due to the dynamical quark mass in the determination of {Lambda}{sub MS} is discussed.

  8. Studying the Sivers and Boer-Mulders function with Lattice QCD

    SciTech Connect

    Bernhard Musch

    2011-11-01

    Transverse momentum dependent parton distribution functions (TMDs) characterize the intrinsic momentum distribution of quarks inside the nucleon. However, they also encode final or initial state interactions of the processes in which they are measured, such as semi-inclusive deep inelastic scattering (SIDIS) or the Drell-Yan process (DY). Consequently certain TMDs are process-dependent and predicted to be equal but opposite in sign for SIDIS and DY. Extending our method on the lattice to non-local operators with U-shaped Wilson lines, we can study these naively time-reversal odd TMDs, in particular the Sivers- and the Boer-Mulders function. We express our results in terms of Fourier-transformed TMDs that appear naturally in the Fourier transformed cross section of, e.g., SIDIS, and in Bessel-weighted asymmetries. We discuss the method, its limitations and preliminary results from an exploratory calculation using lattices generated by the MILC and LHP collaborations.

  9. Lattice QCD Green's functions in maximally Abelian gauge: Infrared Abelian dominance and the quark sector

    NASA Astrophysics Data System (ADS)

    Schröck, Mario; Vogt, Hannes

    2016-01-01

    On lattice gauge field configurations with 2 +1 dynamical quark flavors, we investigate the momentum space quark and gluon propagators in the combined maximally Abelian plus U (1 )3×U (1 )8 Landau gauge. We extract the gluon fields from the lattice link variables and study the diagonal and off-diagonal gluon propagators. We find that the infrared region of the transverse diagonal gluon propagator is strongly enhanced compared to the off-diagonal propagator. The Dirac operator from the Asqtad action is inverted on the diagonal and off-diagonal gluon backgrounds separately. In agreement with the hypothesis of infrared Abelian dominance, we find that the off-diagonal gluon background hardly gives rise to any nontrivial quark dynamics while the quark propagator from the diagonal gluon background closely resembles its Landau gauge counterpart.

  10. Massive Photons: An Infrared Regularization Scheme for Lattice QCD+QED.

    PubMed

    Endres, Michael G; Shindler, Andrea; Tiburzi, Brian C; Walker-Loud, André

    2016-08-12

    Standard methods for including electromagnetic interactions in lattice quantum chromodynamics calculations result in power-law finite-volume corrections to physical quantities. Removing these by extrapolation requires costly computations at multiple volumes. We introduce a photon mass to alternatively regulate the infrared, and rely on effective field theory to remove its unphysical effects. Electromagnetic modifications to the hadron spectrum are reliably estimated with a precision and cost comparable to conventional approaches that utilize multiple larger volumes. A significant overall cost advantage emerges when accounting for ensemble generation. The proposed method may benefit lattice calculations involving multiple charged hadrons, as well as quantum many-body computations with long-range Coulomb interactions. PMID:27563954

  11. Studying the Sivers and Boer-Mulders Function with Lattice QCD

    NASA Astrophysics Data System (ADS)

    Musch, Bernhard U.

    2012-05-01

    Transverse momentum dependent parton distribution functions (TMDs) characterize the intrinsic momentum distribution of quarks inside the nucleon. However, they also encode final or initial state interactions of the processes in which they are measured, such as semi-inclusive deep inelastic scattering (SIDIS) or the Drell-Yan process (DY). Consequently certain TMDs are process-dependent and predicted to be equal but opposite in sign for SIDIS and DY. Extending our method on the lattice to non-local operators with U-shaped Wilson lines, we can study these naively time-reversal odd TMDs, in particular the Sivers- and the Boer-Mulders function. We express our results in terms of Fourier-transformed TMDs that appear naturally in the Fourier transformed cross section of, e.g., SIDIS, and in Bessel-weighted asymmetries. We discuss the method, its limitations and preliminary results from an exploratory calculation using lattices generated by the MILC and LHP collaborations.

  12. B{sub K}-parameter from N{sub f}=2 twisted mass lattice QCD

    SciTech Connect

    Constantinou, M.; Panagopoulos, H.; Skouroupathis, A.; Stylianou, F.; Dimopoulos, P.; Frezzotti, R.; Rossi, G. C.; Gimenez, V.; Lubicz, V.; Papinutto, M.

    2011-01-01

    We present an unquenched N{sub f}=2 lattice computation of the B{sub K} parameter which controls K{sup 0}-K{sup 0} oscillations. A partially quenched setup is employed with two maximally twisted dynamical (sea) light Wilson quarks, and valence quarks of both the maximally twisted and the Osterwalder-Seiler variety. Suitable combinations of these two kinds of valence quarks lead to a lattice definition of the B{sub K} parameter which is both multiplicatively renormalizable and O(a) improved. Employing the nonperturbative RI-MOM scheme, in the continuum limit and at the physical value of the pion mass we get B{sub K}{sup RGI}=0.729{+-}0.030, a number well in line with the existing quenched and unquenched determinations.

  13. B(s) 0-mixing matrix elements from lattice QCD for the Standard Model and beyond

    NASA Astrophysics Data System (ADS)

    Bazavov, A.; Bernard, C.; Bouchard, C. M.; Chang, C. C.; DeTar, C.; Du, Daping; El-Khadra, A. X.; Freeland, E. D.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Kronfeld, A. S.; Laiho, J.; Mackenzie, P. B.; Neil, E. T.; Simone, J.; Sugar, R.; Toussaint, D.; Van de Water, R. S.; Zhou, Ran; Fermilab Lattice; MILC Collaborations

    2016-06-01

    We calculate—for the first time in three-flavor lattice QCD—the hadronic matrix elements of all five local operators that contribute to neutral B0- and Bs-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the expression for the neutral B -meson width difference. We obtain the most precise determination to date of the SU(3)-breaking ratio ξ =1.206 (18 )(6 ), where the second error stems from the omission of charm-sea quarks, while the first encompasses all other uncertainties. The threefold reduction in total uncertainty, relative to the 2013 Flavor Lattice Averaging Group results, tightens the constraint from B mixing on the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle. Our calculation employs gauge-field ensembles generated by the MILC Collaboration with four lattice spacings and pion masses close to the physical value. We use the asqtad-improved staggered action for the light-valence quarks and the Fermilab method for the bottom quark. We use heavy-light meson chiral perturbation theory modified to include lattice-spacing effects to extrapolate the five matrix elements to the physical point. We combine our results with experimental measurements of the neutral B -meson oscillation frequencies to determine the CKM matrix elements |Vt d|=8.00 (34 )(8 )×10-3, |Vt s|=39.0 (1.2 )(0.4 )×10-3, and |Vt d/Vt s|=0.2052 (31 )(10 ), which differ from CKM-unitarity expectations by about 2 σ . These results and others from flavor-changing-neutral currents point towards an emerging tension between weak processes that are mediated at the loop and tree levels.

  14. Towards the chiral limit in QCD

    SciTech Connect

    Shailesh Chandrasekharan

    2006-02-28

    Computing hadronic observables by solving QCD from first principles with realistic quark masses is an important challenge in fundamental nuclear and particle physics research. Although lattice QCD provides a rigorous framework for such calculations many difficulties arise. Firstly, there are no good algorithms to solve lattice QCD with realistically light quark masses. Secondly, due to critical slowing down, Monte Carlo algorithms are able to access only small lattice sizes on coarse lattices. Finally, due to sign problems it is almost impossible to study the physics of finite baryon density. Lattice QCD contains roughly three mass scales: the cutoff (or inverse lattice spacing) a{sup -1}, the confinement scale {Lambda}{sub QCD}, and the pion mass m{sub {pi}}. Most conventional Monte Carlo algorithms for QCD become inefficient in two regimes: when {Lambda}{sub QCD} becomes small compared to a{sup -1} and when m{sub {pi}} becomes small compared to {Lambda}{sub QCD}. The former can be largely controlled by perturbation theory thanks to asymptotic freedom. The latter is more difficult since chiral extrapolations are typically non-analytic and can be unreliable if the calculations are not done at sufficiently small quark masses. For this reason it has been difficult to compute quantities close to the chiral limit. The essential goal behind this proposal was to develop a new approach towards understanding QCD and QCD-like theories with sufficiently light quarks. The proposal was based on a novel cluster algorithm discovered in the strong coupling limit with staggered fermions [1]. This algorithm allowed us to explore the physics of exactly massless quarks and as well as light quarks. Thus, the hope was that this discovery would lead to the complete solution of at least a few strongly coupled QCD-like theories. The solution would be far better than those achievable through conventional methods and thus would be able to shed light on the chiral physics from a new

  15. Matrix elements of left-right four fermion operators and the electropenguin contribution to epsilon'/epsilon in lattice QCD with Wilson fermions

    NASA Astrophysics Data System (ADS)

    Franco, E.; Maiani, L.; Martinelli, G.; Morelli, A.

    1988-10-01

    The K-pi and K-pi-pi elements of left-right four fermion operators in quenched lattice QCD at beta=6 are computed. The soft-pion relations derived from the chiral structure of the operators are checked. A large enhancement of matrix elements is observed and interpreted as the effect of a scalar octet pole in the pi-K channel. This observation has implications for the related calculation of weak matrix elements.

  16. Standing Wave Ground State in High Density, Zero Temperature QCD at Large NC

    NASA Astrophysics Data System (ADS)

    Deryagin, D. V.; Grigoriev, D. Yu.; Rubakov, V. A.

    Chiral symmetry breaking in QCD at zero temperature and high fermionic density is studied in the limit NC → ∞. We evaluate the effective action in the ladder approximation and integrate out fermions by introducing the bilocal field Σ(x, y), which enters the action as the mass operator for fermions. It is argued that at large fermionic chemical potential the mass operator Σ(x, y) has a small but nonvanishing expectation value. The condensate of the field Σ(x, y) and the fermionic condensate < bar ψ (x) ψ (y)> are inhomogeneous and anisotropic, so that the ground state has the structure of the standing wave with respect to these order parameters. Unlike possible color superconductivity, this symmetry breaking occurs to the leading order in 1/NC.

  17. $B\\to\\pi\\ell\\ell$ Form Factors for New-Physics Searches from Lattice QCD

    SciTech Connect

    Bailey, Jon A.

    2015-10-07

    The rare decay B→πℓ+- 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 agrees with the recent measurement from the LHCb experiment [R. Aaij et al., J. High Energy Phys. 12 (2012) 125].

  18. Renormalization of quark propagators from twisted-mass lattice QCD at N{sub f}=2

    SciTech Connect

    Blossier, B.; Boucaud, Ph.; Pene, O.; Petrov, K.; Brinet, M.; Liu, Z.; Morenas, V.

    2011-04-01

    We present results concerning the nonperturbative evaluation of the renormalization constant for the quark field, Z{sub q}, from lattice simulations with twisted-mass quarks and three values of the lattice spacing. We use the regularization-invariant momentum-subtraction (RI'-MOM) scheme. Z{sub q} has very large lattice spacing artefacts; it is considered here as a test bed to elaborate accurate methods which will be used for other renormalization constants. We recall and develop the nonperturbative correction methods and propose tools to test the quality of the correction. These tests are also applied to the perturbative correction method. We check that the lattice-spacing artefacts indeed scale as a{sup 2}p{sup 2}. We then study the running of Z{sub q} with particular attention to the nonperturbative effects, presumably dominated by the dimension-two gluon condensate in Landau gauge. We show indeed that this effect is present, and not small. We check its scaling in physical units, confirming that it is a continuum effect. It gives a {approx}4% contribution at 2 GeV. Different variants are used in order to test the reliability of our result and estimate the systematic uncertainties. Finally, combining all our results and using the known Wilson coefficient of , we find g{sup 2}({mu}{sup 2}){sub {mu}}{sup 2}{sub CM}=2.01(11)({sub -0.73}{sup +0.61})GeV{sup 2} at {mu}=10 GeV, the local operator A{sup 2} being renormalized in the MS scheme. This last result is in fair agreement within uncertainties with the value independently extracted from the strong coupling constant. We convert the nonperturbative part of Z{sub q} from the regularization-invariant momentum-subtraction (RI'-MOM) scheme to MS. Our result for the quark field renormalization constant in the MS scheme is Z{sub q} {sup MS} {sup pert}((2 GeV){sup 2},g{sub bare}{sup 2})=0.750(3)(7)-0.313(20)(g{sub bare}{sup 2}-1.5) for the perturbative contribution and Z{sub q

  19. $$B^0_{(s)}$$-mixing matrix elements from lattice QCD for the Standard Model and beyond

    DOE PAGESBeta

    Bazavov, A.; Bernard, C.; Bouchard, C. M.; Chang, C. C.; DeTar, C.; Du, Daping; El-Khadra, A. X.; Freeland, E. D.; Gamiz, E.; Gottlieb, Steven; et al

    2016-06-28

    We calculate—for the first time in three-flavor lattice QCD—the hadronic matrix elements of all five local operators that contribute to neutral B0- and Bs-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the expression for the neutral B-meson width difference. We obtain the most precise determination to date of the SU(3)-breaking ratio ξ=1.206(18)(6), where the second errormore » stems from the omission of charm-sea quarks, while the first encompasses all other uncertainties. The threefold reduction in total uncertainty, relative to the 2013 Flavor Lattice Averaging Group results, tightens the constraint from B mixing on the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle. Our calculation employs gauge-field ensembles generated by the MILC Collaboration with four lattice spacings and pion masses close to the physical value. We use the asqtad-improved staggered action for the light-valence quarks and the Fermilab method for the bottom quark. We use heavy-light meson chiral perturbation theory modified to include lattice-spacing effects to extrapolate the five matrix elements to the physical point. We combine our results with experimental measurements of the neutral B-meson oscillation frequencies to determine the CKM matrix elements |Vtd| = 8.00(34)(8)×10-3, |Vts| = 39.0(1.2)(0.4)×10-3, and |Vtd/Vts| = 0.2052(31)(10), which differ from CKM-unitarity expectations by about 2σ. In addition, these results and others from flavor-changing-neutral currents point towards an emerging tension between weak processes that are mediated at the loop and tree levels.« less

  20. $X(3873$ and $Y(4140)$ using diquark-antidiquark operators with lattice QCD

    SciTech Connect

    Padmanath, M.; Lang, C.  B.; Prelovsek Komelj, Sasa

    2015-08-01

    We perform a lattice study of charmonium-like mesons with $J^{PC}=1^{++}$ and three quark contents $\\bar cc \\bar du$, $\\bar cc(\\bar uu+\\bar dd)$ and $\\bar cc \\bar ss$, where the later two can mix with $\\bar cc$. This simulation with $N_f=2$ and $m_\\pi=266$ MeV aims at the possible signatures of four-quark exotic states. We utilize a large basis of $\\bar cc$, two-meson and diquark-antidiquark interpolating fields, with diquarks in both anti-triplet and sextet color representations. A lattice candidate for X(3872) with I=0 is observed very close to the experimental state only if both $\\bar cc$ and $D\\bar D^*$ interpolators are included; the candidate is not found if diquark-antidiquark and $D\\bar D^*$ are used in the absence of $\\bar cc$. No candidate for neutral or charged X(3872), or any other exotic candidates are found in the I=1 channel. We also do not find signatures of exotic $\\bar cc\\bar ss$ candidates below 4.3 GeV, such as Y(4140). Possible physics and methodology related reasons for that are discussed. Along the way, we present the diquark-antidiquark operators as linear combinations of the two-meson operators via the Fierz transformations.

  1. $X(3873$ and $Y(4140)$ using diquark-antidiquark operators with lattice QCD

    DOE PAGESBeta

    Padmanath, M.; Lang, C.  B.; Prelovsek Komelj, Sasa

    2015-08-01

    We perform a lattice study of charmonium-like mesons withmore » $$J^{PC}=1^{++}$$ and three quark contents $$\\bar cc \\bar du$$, $$\\bar cc(\\bar uu+\\bar dd)$$ and $$\\bar cc \\bar ss$$, where the later two can mix with $$\\bar cc$$. This simulation with $N_f=2$ and $$m_\\pi=266$$ MeV aims at the possible signatures of four-quark exotic states. We utilize a large basis of $$\\bar cc$$, two-meson and diquark-antidiquark interpolating fields, with diquarks in both anti-triplet and sextet color representations. A lattice candidate for X(3872) with I=0 is observed very close to the experimental state only if both $$\\bar cc$$ and $$D\\bar D^*$$ interpolators are included; the candidate is not found if diquark-antidiquark and $$D\\bar D^*$$ are used in the absence of $$\\bar cc$$. No candidate for neutral or charged X(3872), or any other exotic candidates are found in the I=1 channel. We also do not find signatures of exotic $$\\bar cc\\bar ss$$ candidates below 4.3 GeV, such as Y(4140). Possible physics and methodology related reasons for that are discussed. Along the way, we present the diquark-antidiquark operators as linear combinations of the two-meson operators via the Fierz transformations.« less

  2. Density functional theory study of the effect of helium clusters on tritium-containing palladium lattices.

    PubMed

    Das, N K; de Leeuw, N H

    2015-12-01

    Density functional theory (DFT) calculations have been employed to calculate the energetics, structures and migration behaviour of helium in palladium tritides. Increasing the tritium concentration in palladium leads to a decrease in the formation energies of helium clusters, indicating that He clusters can form in the lattices. The calculated results show less lattice expansion in Pd defect-containing lattices compared to the perfect lattice owing to smaller lattice distortions. The lowest energy migration path for helium diffusion is along octahedral-tetrahedral-octahedral sites but the energy barrier increases with increasing tritium concentration. Repulsive interactions occur between Pd d and He s orbitals, suggesting that displacement of the metal atoms in the lattice leads to growth of pressure inside the lattices. This process may change the microstructural properties leading to the degradation of the material. PMID:26459746

  3. Density functional theory study of the effect of helium clusters on tritium-containing palladium lattices

    NASA Astrophysics Data System (ADS)

    Das, N. K.; de Leeuw, N. H.

    2015-12-01

    Density functional theory (DFT) calculations have been employed to calculate the energetics, structures and migration behaviour of helium in palladium tritides. Increasing the tritium concentration in palladium leads to a decrease in the formation energies of helium clusters, indicating that He clusters can form in the lattices. The calculated results show less lattice expansion in Pd defect-containing lattices compared to the perfect lattice owing to smaller lattice distortions. The lowest energy migration path for helium diffusion is along octahedral-tetrahedral-octahedral sites but the energy barrier increases with increasing tritium concentration. Repulsive interactions occur between Pd d and He s orbitals, suggesting that displacement of the metal atoms in the lattice leads to growth of pressure inside the lattices. This process may change the microstructural properties leading to the degradation of the material.

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

    SciTech Connect

    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.

  5. Interacting fermions in one-dimensional disordered lattices: Exploring localization and transport properties with lattice density-functional theories

    NASA Astrophysics Data System (ADS)

    Vettchinkina, V.; Kartsev, A.; Karlsson, D.; Verdozzi, C.

    2013-03-01

    We investigate the static and dynamical behavior of one-dimensional interacting fermions in disordered Hubbard chains contacted to semi-infinite leads. The chains are described via the repulsive Anderson-Hubbard Hamiltonian, using static and time-dependent lattice density-functional theory. The dynamical behavior of our quantum transport system is studied using an integration scheme available in the literature, which we modify via the recursive Lanczos method to increase its efficiency. To quantify the degree of localization due to disorder and interactions, we adapt the definition of the inverse participation ratio to obtain an indicator which is suitable for quantum transport geometries and can be obtained within density-functional theory. Lattice density-functional theories are reviewed and, for contacted chains, we analyze the merits and limits of the coherent-potential approximation in describing the spectral properties, with interactions included via lattice density-functional theory. Our approach appears to be able to capture complex features due to the competition between disorder and interactions. Specifically, we find a dynamical enhancement of delocalization in the presence of a finite bias and an increase of the steady-state current induced by interparticle interactions. This behavior is corroborated by results for the time-dependent densities and for the inverse participation ratio. Using short isolated chains with interaction and disorder, a brief comparative analysis between time-dependent density-functional theory and exact results is then given, followed by general concluding remarks.

  6. Two nucleon systems at mπ˜450 MeV from lattice QCD

    NASA Astrophysics Data System (ADS)

    Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Beane, Silas R.; Chang, Emmanuel; Detmold, William; Nplqcd Collaboration

    2015-12-01

    Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass of mπ˜450 MeV in three spatial volumes using nf=2 +1 flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be Bd=14. 4-2.6+3.2 MeV , while the dineutron is bound by Bn n=12. 5-5.0+3.0 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 expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. 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.

  7. Spectrum and Bethe-Salpeter amplitudes of Ω baryons from lattice QCD

    NASA Astrophysics Data System (ADS)

    Liang, Jian; Sun, Wei; Chen, Ying; Qiu, Wei-Feng; Gong, Ming; Liu, Chuan; Liu, Yu-Bin; Liu, Zhao-Feng; Ma, Jian-Ping; Zhang, Jian-Bo; CLQCD Collaboration

    2016-04-01

    The Ω baryons with J P = 3/2±, 1/2± are studied on the lattice in the quenched approximation. Their mass levels are ordered as M 3/2+ < M 3/2‑ ≈ M 1/2‑ < M 1/2+ , as is expected from the constituent quark model. The mass values are also close to those of the four Ω states observed in experiments. We calculate the Bethe-Salpeter amplitudes of Ω(3/2+) and Ω(1/2+) and find there is a radial node for the Ω(1/2+) Bethe-Salpeter amplitude, which may imply that Ω(1/2+) is an orbital excitation of Ω baryons as a member of the supermultiplet in the SU(6) ⊗ O(3) quark model description. Our results are helpful for identifying the quantum numbers of experimentally observed Ω states. The numerical calculations were carried out on Tianhe-1A at the National Supercomputer Center (NSCC) in Tianjin. Supported by National Science Foundation of China (NSFC) (11105153, 11335001, 11405053), Youth Innovation Promotion Association of CAS, NSFC (11261130311) (CRC 110 by DFG and NSFC)

  8. Two nucleon systems at mπ~450MeV from lattice QCD

    DOE PAGESBeta

    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

  9. S-wave π-K scattering length from lattice QCD

    NASA Astrophysics Data System (ADS)

    Sasaki, Kiyoshi; Ishizuka, Naruhito; Yamazaki, Takeshi; Oka, Makoto

    2009-10-01

    We present the S-wave π-K scattering lengths for both the isospin 1/2 and 3/2 channels evaluated by using the finite size formula. We utilize the Nf=2+1 gauge configurations generated on 32^3 x64 lattice using the Iwasaki gauge action and the O(a)-improved Wilson action at 1/a = 2.17 GeV. The quark masses correspond to mπ = 0.30 - 0.70 GeV. For I=1/2, to separate the effects from excited states, we construct a 2x2 matrix of the time correlation function and diagonalize it. Here, we adopt the two kinds of operators, su and π-K. Our preliminary results show signs of the scattering lengths in agreement with experiment, namely attraction in I=1/2 and repulsion in I=3/2. We investigate the quark-mass dependence of the scattering length and also discuss the limitation of chiral perturbation theory.

  10. Excited meson radiative transitions from lattice QCD using variationally optimized operators

    SciTech Connect

    Shultz, Christian J.; Dudek, Jozef J.; Edwards, Robert G.

    2015-06-02

    We explore the use of 'optimized' operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and non-zero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form-factors and transitions of pseudoscalar and vector meson excitations. In conclusion, the dependence on photon virtuality for a number of form-factors and transitions is extracted and some discussion of excited-state phenomenology is presented.

  11. F(1) for B (forward) D*ln from lattice QCD

    SciTech Connect

    A.S. Kronfeld, P.B. Mackenzie and J.N. Simone

    2002-07-12

    The authors would like to determine |V{sub cb}| from the exclusive semi-leptonic decay B{yields}D*lv. The differential decay rate is d{Lambda}/dw = G{sub F}{sup 2}/4{pi}{sup 3}(w{sup 2}-1){sup 1/2}m{sub D*}{sup 3} (m{sub B}-m{sub D*}){sup 2}G(w)|V{sub cb}|{sup 2}|F{sub B{yields}D*}(w)|{sup 2}, where w = v {center_dot} v{prime} and G(1) = 1. At zero recoil (w = 1) heavy-quark symmetry requires F{sub B{yields}D*}(1) to be close to 1. So, |V{sub cb}| is determined by dividing measurements of d{Lambda}/dw by the phase space and well-known factors, and extrapolating to w {yields} 1. This yields |V{sub cb}|F{sub B{yields}D*}(1), and F{sub B{yields}D*}(1) is taken from ''theory''. To date models [1] or a combination of a rigorous inequality plus judgement [2] have been used to estimate F{sub B{yields}D*}(1) - 1. In this work [3] they calculate F{sub B{yields}D*}(1) with lattice gauge theory, in the so-called quenched approximation, but the uncertainty from quenching is included in the error budget.

  12. Effects of the quark field on the ghost propagator of lattice Landau gauge QCD

    SciTech Connect

    Furui, Sadataka; Nakajima, Hideo

    2006-05-01

    Infrared features of the ghost propagator of color-diagonal and color antisymmetric ghost propagator of quenched SU(2) and quenched SU(3) are compared with those of unquenched Kogut-Susskind fermion SU(3) lattice Landau gauge. We compare (i) the fluctuation of the ghost propagator (ii) the ghost condensate parameter v of the local composite operator (LCO) approach, and (iii) the Binder cumulant of color antisymmetric ghost propagator between quenched and unquenched configurations. The color-diagonal SU(3) ghost dressing function of unquenched configurations has weaker singularity than the quenched configurations. In both cases fluctuations become large in q<0.5 GeV. The ghost condensate parameter v in the ghost propagator of the unquenched MILC{sub c} configuration samples is {approx}0.002-0.04 GeV{sup 2} while that of the SU(2) parallel tempering samples is consistent with 0. The Binder cumulant defined as U(q)=1-(1/3)(<{phi}-vector{sup 4}>/(<{phi}-vector{sup 2}>){sup 2}), where {phi}-vector(q) is the color antisymmetric ghost propagator measured by the sample average of gauge fixed configurations via parallel tempering method, becomes {approx}4/9 in all the momentum region. The Binder cumulant of the color antisymmetric ghost propagator of quenched SU(2) can be explained by the 3D Gaussian distribution, but that of the unquenched MILC{sub c} deviates slightly from that of the eight-dimensional Gaussian distribution. The stronger singularity and large fluctuation in the quenched configuration could be the cause of the deviation of the Kugo-Ojima confinement parameter c from 1, and the presence of ordering in the ghost propagator of unquenched configurations makes it closer to 1.

  13. Mass modification of /D-meson at finite density in QCD sum rule

    NASA Astrophysics Data System (ADS)

    Hayashigaki1, A.

    2000-08-01

    We evaluate the mass shift of isospin-averaged /D-meson in the nuclear medium. Borel-transformed QCD sum rules are used to describe an interaction between the /D-meson and a nucleon by taking into account all the lowest dimension-4 operators in the operator product expansion (OPE). We find at normal matter density the /D-meson mass shift is about /10 times (/~50 MeV) larger than that of /J/ψ. This originates from the fact that the dominant contribution in the OPE for the /D-meson is the nucleon matrix element of mcq¯q, where mc is the charm-quark mass and /q denotes light quarks. We also discuss that the mass shift of the /D-meson in nuclear matter may cause the level crossings of the charmonium states and the /DD¯ threshold. This suggests an additional mechanism of the /J/ψ suppression in high energy heavy-ion collisions.

  14. Quantum Lattice Fluctuations in the Charge Density Wave State beyond the Adiabatic Approximation

    NASA Astrophysics Data System (ADS)

    Shida, Keisuke; Watanabe, Yuko; Gomi, Hiroki; Takahashi, Akira; Tomita, Norikazu

    2015-12-01

    We have developed a tractable numerical method in which large-amplitude quantum lattice fluctuations can be described beyond the adiabatic approximation using the coherent state representation of phonons. A many-body wave function is constructed by the superposition of direct products of non-orthogonal Slater determinants for electrons and coherent states of phonons. Both orbitals in all the Slater determinants and the amplitudes of all the coherent states are simultaneously optimized. We apply the method to the one-dimensional Su-Schrieffer-Heeger model with the on-site and nearest-neighbor-site Coulomb interactions. It is shown the lattice fluctuations in doped charge density wave (CDW) systems are described by the translational and vibrational motion of lattice solitons. Such lattice solitons induce bond alternation in the doped CDW system while the lattice becomes equidistant in the half-filled CDW system.

  15. Nonperturbative renormalization of the axial current in Nf=3 lattice QCD with Wilson fermions and a tree-level improved gauge action

    NASA Astrophysics Data System (ADS)

    Bulava, John; Della Morte, Michele; Heitger, Jochen; Wittemeier, Christian

    2016-06-01

    We nonperturbatively determine the renormalization factor of the axial vector current in lattice QCD with Nf=3 flavors of Wilson-clover fermions and the tree-level Symanzik-improved gauge action. The (by now standard) renormalization condition is derived from the massive axial Ward identity, and it is imposed among Schrödinger functional states with large overlap on the lowest lying hadronic state in the pseudoscalar channel, in order to reduce kinematically enhanced cutoff effects. We explore a range of couplings relevant for simulations at lattice spacings of ≈0.09 fm and below. An interpolation formula for ZA(g02) , smoothly connecting the nonperturbative values to the 1-loop expression, is provided together with our final results.

  16. Δ S =2 and Δ C =2 bag parameters in the standard model and beyond from Nf=2 +1 +1 twisted-mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Carrasco, N.; Dimopoulos, P.; Frezzotti, R.; Lubicz, V.; Rossi, G. C.; Simula, S.; Tarantino, C.; ETM Collaboration

    2015-08-01

    We present unquenched lattice QCD results for the matrix elements of four-fermion operators relevant to the description of the neutral K and D mixing in the standard model and its extensions. We have employed simulations with Nf=2 +1 +1 dynamical sea quarks at three values of the lattice spacings in the interval 0.06-0.09 fm and pseudoscalar meson masses in the range 210-450 MeV. Our results are extrapolated to the continuum limit and to the physical pion mass. Renormalization constants have been determined nonperturbatively in the RI-MOM scheme. In particular, for the kaon bag parameter, which is relevant for the K¯ 0-K0 mixing in the standard model, we obtain BKRGI=0.717 (24 ) .

  17. The high density phase of the k-NN hard core lattice gas model

    NASA Astrophysics Data System (ADS)

    Nath, Trisha; Rajesh, R.

    2016-07-01

    The k-NN hard core lattice gas model on a square lattice, in which the first k next nearest neighbor sites of a particle are excluded from being occupied by another particle, is the lattice version of the hard disc model in two dimensional continuum. It has been conjectured that the lattice model, like its continuum counterpart, will show multiple entropy-driven transitions with increasing density if the high density phase has columnar or striped order. Here, we determine the nature of the phase at full packing for k up to 820 302 . We show that there are only eighteen values of k, all less than k  =  4134, that show columnar order, while the others show solid-like sublattice order.

  18. Charmed and light pseudoscalar meson decay constants from four-flavor lattice QCD with physical light quarks

    SciTech Connect

    Bazavov, A.; Bernard, C.; Komijani, J.; Bouchard, C. M.; DeTar, C.; Foley, J.; Levkova, L.; Du, D.; Laiho, J.; El-Khadra, A. X.; Freeland, E. D.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Kim, J.; Toussaint, D.; Kronfeld, A. S.; Mackenzie, P. B.; Simone, J. N.; Van de Water, R. S.; Zhou, R.; Neil, E. T.; Sugar, R.

    2014-10-30

    We compute the leptonic decay constants fD+, fDs, and fK+ and the quark-mass ratios mc/ms and ms/ml in unquenched lattice QCD using the experimentally determined value of fπ+ for normalization. We use the MILC highly improved staggered quark ensembles with four dynamical quark flavors—up, down, strange, and charm—and with both physical and unphysical values of the light sea-quark masses. The use of physical pions removes the need for a chiral extrapolation, thereby eliminating a significant source of uncertainty in previous calculations. Four different lattice spacings ranging from a0.06 to 0.15 fm are included in the analysis to control the extrapolation to the

  19. Symmetry analysis of translational symmetry broken density waves: Application to hexagonal lattices in two dimensions

    NASA Astrophysics Data System (ADS)

    Venderbos, J. W. F.

    2016-03-01

    In this work we introduce a symmetry classification for electronic density waves which break translational symmetry due to commensurate wave-vector modulations. The symmetry classification builds on the concept of extended point groups: symmetry groups which contain, in addition to the lattice point group, translations that do not map the enlarged unit cell of the density wave to itself, and become "nonsymmorphic"-like elements. Multidimensional representations of the extended point group are associated with degenerate wave vectors. Electronic properties such as (nodal) band degeneracies and topological character can be straightforwardly addressed, and often follow directly. To further flesh out the idea of symmetry, the classification is constructed so as to manifestly distinguish time-reversal invariant charge (i.e., site and bond) order, and time-reversal breaking flux order. For the purpose of this work, we particularize to spin-rotation invariant density waves. As a first example of the application of the classification we consider the density waves of a simple single- and two-orbital square lattice model. The main objective, however, is to apply the classification to two-dimensional (2D) hexagonal lattices, specifically the triangular and the honeycomb lattices. The multicomponent density waves corresponding to the commensurate M -point ordering vectors are worked out in detail. To show that our results generally apply to 2 D hexagonal lattices, we develop a general low-energy SU(3 ) theory of (spinless) saddle-point electrons.

  20. Lattice QCD workflows

    SciTech Connect

    Piccoli, Luciano; Kowalkowski, James B.; Simone, James N.; Sun, Xian-He; Jin, Hui; Holmgren, Donald J.; Seenu, Nirmal; Singh, Amitoj G.; /Fermilab

    2008-12-01

    This paper discusses the application of existing workflow management systems to a real world science application (LQCD). Typical workflows and execution environment used in production are described. Requirements for the LQCD production system are discussed. The workflow management systems Askalon and Swift were tested by implementing the LQCD workflows and evaluated against the requirements. We report our findings and future work.

  1. High-loop perturbative renormalization constants for Lattice QCD (III): three-loop quark currents for Iwasaki gauge action and Wilson fermions

    NASA Astrophysics Data System (ADS)

    Brambilla, M.; Di Renzo, F.; Hasegawa, M.

    2014-07-01

    This is the third of a series of papers on three-loop computation of renormalization constants for Lattice QCD. Our main points of interest are results for the regularization defined by the Iwasaki gauge action and Wilson fermions. Our results for quark bilinears renormalized according to the RI'-MOM scheme can be compared to non-perturbative results. The latter are available for twisted mass QCD: being defined in the chiral limit, the renormalization constants must be the same. We also address more general problems. In particular, we discuss a few methodological issues connected to summing the perturbative series such as the effectiveness of boosted perturbation theory and the disentanglement of irrelevant and finite-volume contributions. Discussing these issues we consider not only the new results of this paper, but also those for the regularization defined by the tree-level Symanzik improved gauge action and Wilson fermions, which we presented in a recent paper of ours. We finally comment on the extent to which the techniques we put at work in the NSPT context can provide a fresher look into the lattice version of the RI'-MOM scheme.

  2. B{yields}{pi}l{nu} semileptonic form factor from three-flavor lattice QCD: A model-independent determination of |V{sub ub}|

    SciTech Connect

    Bailey, Jon A.; Kronfeld, A. S.; Mackenzie, P. B.; Okamoto, M.; Simone, J. N.; Water, R. S. van de; Bernard, C.; Laiho, J.; DeTar, C.; Levkova, L.; Di Pierro, M.; El-Khadra, A. X.; Evans, R. T.; Gamiz, E.; Freeland, E. D.; Gottlieb, Steven; Heller, U. M.; Hetrick, J. E.; Sugar, R.; Toussaint, D.

    2009-03-01

    We calculate the form factor f{sub +}(q{sup 2}) for B-meson semileptonic decay in unquenched lattice QCD with 2+1 flavors of light sea quarks. We use Asqtad-improved staggered light quarks and a Fermilab bottom quark on gauge configurations generated by the MILC Collaboration. We simulate with several light-quark masses and at two lattice spacings, and extrapolate to the physical quark mass and continuum limit using heavy-light meson staggered chiral perturbation theory. We then fit the lattice result for f{sub +}(q{sup 2}) simultaneously with that measured by the BABAR experiment using a parameterization of the form-factor shape in q{sup 2}, which relies only on analyticity and unitarity in order to determine the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}|. This approach reduces the total uncertainty in |V{sub ub}| by combining the lattice and experimental information in an optimal, model-independent manner. We find a value of |V{sub ub}|x10{sup 3}=3.38{+-}0.36.

  3. B → Dℓν form factors at nonzero recoil and |Vcb| from 2+1-flavor lattice QCD

    SciTech Connect

    Bailey, Jon A.

    2015-08-10

    We present the first unquenched lattice-QCD calculation of the hadronic form factors for the exclusive decay B¯→Dℓν¯ at nonzero recoil. We carry out numerical simulations on 14 ensembles of gauge-field configurations generated with 2+1 flavors of asqtad-improved staggered sea quarks. The ensembles encompass a wide range of lattice spacings (approximately 0.045 to 0.12 fm) and ratios of light (up and down) to strange sea-quark masses ranging from 0.05 to 0.4. For the b and c valence quarks we use improved Wilson fermions with the Fermilab interpretation, while for the light valence quarks we use asqtad-improved staggered fermions. We extrapolate our results to the physical point using rooted staggered heavy-light meson chiral perturbation theory. We then parametrize the form factors and extend them to the full kinematic range using model-independent functions based on analyticity and unitarity. We present our final results for f+(q2) and f0(q2), including statistical and systematic errors, as coefficients of a series in the variable z and the covariance matrix between these coefficients. We then fit the lattice form-factor data jointly with the experimentally measured differential decay rate from BABAR to determine the CKM matrix element, |Vcb|=(39.6 ± 1.7QCD+exp ± 0.2QED) × 10–3. As a byproduct of the joint fit we obtain the form factors with improved precision at large recoil. In conclusion, we use them to update our calculation of the ratio R(D) in the Standard Model, which yields R(D)=0.299(11).

  4. B →D ℓν form factors at nonzero recoil and |Vc b| from 2 +1 -flavor lattice QCD

    NASA Astrophysics Data System (ADS)

    Bailey, Jon A.; Bazavov, A.; Bernard, C.; Bouchard, C. M.; DeTar, C.; Du, Daping; El-Khadra, A. X.; Foley, J.; Freeland, E. D.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Komijani, J.; Kronfeld, A. S.; Laiho, J.; Levkova, L.; Mackenzie, P. B.; Neil, E. T.; Qiu, Si-Wei; Simone, J.; Sugar, R.; Toussaint, D.; Van de Water, R. S.; Zhou, Ran; Fermilab Lattice; MILC Collaborations

    2015-08-01

    We present the first unquenched lattice-QCD calculation of the hadronic form factors for the exclusive decay B ¯→D ℓν ¯ at nonzero recoil. We carry out numerical simulations on 14 ensembles of gauge-field configurations generated with 2 +1 flavors of asqtad-improved staggered sea quarks. The ensembles encompass a wide range of lattice spacings (approximately 0.045 to 0.12 fm) and ratios of light (up and down) to strange sea-quark masses ranging from 0.05 to 0.4. For the b and c valence quarks we use improved Wilson fermions with the Fermilab interpretation, while for the light valence quarks we use asqtad-improved staggered fermions. We extrapolate our results to the physical point using rooted staggered heavy-light meson chiral perturbation theory. We then parametrize the form factors and extend them to the full kinematic range using model-independent functions based on analyticity and unitarity. We present our final results for f+(q2) and f0(q2), including statistical and systematic errors, as coefficients of a series in the variable z and the covariance matrix between these coefficients. We then fit the lattice form-factor data jointly with the experimentally measured differential decay rate from BABAR to determine the CKM matrix element, |Vc b|=(39.6 ±1. 7QCD +exp±0. 2QED)×10-3 . As a byproduct of the joint fit we obtain the form factors with improved precision at large recoil. Finally, we use them to update our calculation of the ratio R (D ) in the Standard Model, which yields R (D )=0.299 (11 ).

  5. On the lattice Boltzmann method for multiphase flows with large density ratios

    NASA Astrophysics Data System (ADS)

    Kim, Seung Hyun; Pitsch, Heinz

    2015-12-01

    An analysis of the lattice Boltzmann (LB) method for multiphase flows with large density ratios is presented. It is shown that for incompressible, multiphase LB methods, the divergence-free condition is not satisfied within the formal accuracy of the LB method, when the density ratio between the two phases is large enough. The discrete differentiation-by-parts rule is responsible for this error. A new multiphase LB method to resolve this issue is proposed.

  6. Λb→pl⁻ν¯l form factors from lattice QCD with static b quarks

    SciTech Connect

    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 14 GeV²≤q²≤q²max, and obtain the integral ∫max 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.

  7. Thermodynamics of lattice OCD

    SciTech Connect

    Matsuoka, H.

    1985-01-01

    The thermodynamic consequences of QCD are explored in the framework of lattice gauge theory. Attention is focused upon the nature of the chiral symmetry restoration transition at finite temperature and at finite baryon density, and possible strategies for identifying relevant thermodynamic phases are discussed. Some numerical results are presented on the chiral symmetry restoration in the SU(2) gauge theory at high baryon density. The results suggest that with T approx. = 110 MeV there is a second order restoration transition at the critical baryon density n/sub B//sup c/ approx. = 0.62 fm/sup -3/.

  8. Extended Bose Hubbard model of interacting bosonic atoms in optical lattices: From superfluidity to density waves

    SciTech Connect

    Mazzarella, G.; Giampaolo, S. M.; Illuminati, F.

    2006-01-15

    For systems of interacting, ultracold spin-zero neutral bosonic atoms, harmonically trapped and subject to an optical lattice potential, we derive an Extended Bose Hubbard (EBH) model by developing a systematic expansion for the Hamiltonian of the system in powers of the lattice parameters and of a scale parameter, the lattice attenuation factor. We identify the dominant terms that need to be retained in realistic experimental conditions, up to nearest-neighbor interactions and nearest-neighbor hoppings conditioned by the on-site occupation numbers. In the mean field approximation, we determine the free energy of the system and study the phase diagram both at zero and at finite temperature. At variance with the standard on site Bose Hubbard model, the zero-temperature phase diagram of the EBH model possesses a dual structure in the Mott insulating regime. Namely, for specific ranges of the lattice parameters, a density wave phase characterizes the system at integer fillings, with domains of alternating mean occupation numbers that are the atomic counterparts of the domains of staggered magnetizations in an antiferromagnetic phase. We show as well that in the EBH model, a zero-temperature quantum phase transition to pair superfluidity is, in principle, possible, but completely suppressed at the lowest order in the lattice attenuation factor. Finally, we determine the possible occurrence of the different phases as a function of the experimentally controllable lattice parameters.

  9. Resource Letter QCD-1: Quantum chromodynamics

    NASA Astrophysics Data System (ADS)

    Kronfeld, Andreas S.; Quigg, Chris

    2010-11-01

    This Resource Letter provides a guide to the literature on quantum chromodynamics (QCD), the relativistic quantum field theory of the strong interactions. Journal articles, books, and other documents are cited for the following topics: Quarks and color, the parton model, Yang-Mills theory, experimental evidence for color, QCD as a color gauge theory, asymptotic freedom, QCD for heavy hadrons, QCD on the lattice, the QCD vacuum, pictures of quark confinement, early and modern applications of perturbative QCD, the determination of the strong coupling and quark masses, QCD and the hadron spectrum, hadron decays, the quark-gluon plasma, the strong nuclear interaction, and QCD's role in nuclear physics.

  10. QCD bound states and their response to extremes of temperature and density.

    SciTech Connect

    Maris, P.

    1998-06-09

    We describe the application of Dyson-Schwinger equations to the calculation of hadron observable. The studies at zero temperature (T) and quark chemical potential ({mu}) provide a springboard for the extension to finite-(T, {mu}). Our exemplars highlight that much of hadronic physics can be understood as simply a manifestation of the nonperturbative, momentum-dependent dressing of the elementary Schwinger functions in QCD.

  11. FOREWORD: Extreme QCD 2012 (xQCD)

    NASA Astrophysics Data System (ADS)

    Alexandru, Andrei; Bazavov, Alexei; Liu, Keh-Fei

    2013-04-01

    The Extreme QCD 2012 conference, held at the George Washington University in August 2012, celebrated the 10th event in the series. It has been held annually since 2003 at different locations: San Carlos (2011), Bad Honnef (2010), Seoul (2009), Raleigh (2008), Rome (2007), Brookhaven (2006), Swansea (2005), Argonne (2004), and Nara (2003). As usual, it was a very productive and inspiring meeting that brought together experts in the field of finite-temperature QCD, both theoretical and experimental. On the experimental side, we heard about recent results from major experiments, such as PHENIX and STAR at Brookhaven National Laboratory, ALICE and CMS at CERN, and also about the constraints on the QCD phase diagram coming from astronomical observations of one of the largest laboratories one can imagine, neutron stars. The theoretical contributions covered a wide range of topics, including QCD thermodynamics at zero and finite chemical potential, new ideas to overcome the sign problem in the latter case, fluctuations of conserved charges and how they allow one to connect calculations in lattice QCD with experimentally measured quantities, finite-temperature behavior of theories with many flavors of fermions, properties and the fate of heavy quarkonium states in the quark-gluon plasma, and many others. The participants took the time to write up and revise their contributions and submit them for publication in these proceedings. Thanks to their efforts, we have now a good record of the ideas presented and discussed during the workshop. We hope that this will serve both as a reminder and as a reference for the participants and for other researchers interested in the physics of nuclear matter at high temperatures and density. To preserve the atmosphere of the event the contributions are ordered in the same way as the talks at the conference. We are honored to have helped organize the 10th meeting in this series, a milestone that reflects the lasting interest in this

  12. Λb→Λ ℓ+ℓ- form factors, differential branching fraction, and angular observables from lattice QCD with relativistic b quarks

    NASA Astrophysics Data System (ADS)

    Detmold, William; Meinel, Stefan

    2016-04-01

    Using (2 +1 )-flavor lattice QCD, we compute the 10 form factors describing the Λb→Λ matrix elements of the b →s vector, axial vector, and tensor currents. The calculation is based on gauge field ensembles generated by the RBC and UKQCD Collaborations with a domain-wall action for the u , d , and s quarks and the Iwasaki gauge action. The b quark is implemented using an anisotropic clover action, tuned nonperturbatively to the physical point, and the currents are renormalized with a mostly nonperturbative method. We perform simultaneous chiral, continuum, and kinematic extrapolations of the form factors through modified z expansions. Using our form factor results, we obtain precise predictions for the Λb→Λ (→p+π-)μ+μ- differential branching fraction and angular observables in the Standard Model.

  13. Investigation of the second moment of the nucleon's g{sub 1} and g{sub 2} structure functions in two-flavor lattice QCD

    SciTech Connect

    Goeckeler, M.; Horsley, R.; Pleiter, D.; Zanotti, J.M.; Rakow, P.E.L.; Schaefer, A.; Schierholz, G.; Stueben, H.

    2005-09-01

    The reduced matrix elements a{sub 2} and d{sub 2} are computed in lattice QCD with N{sub f}=2 flavors of light dynamical (sea) quarks. For proton and neutron targets we obtain as our best estimates d{sub 2}{sup (p)}=0.004(5) and d{sub 2}{sup (n)}=-0.001(3), respectively, in the MS scheme at Q{sup 2}=5 GeV{sup 2}, while for a{sub 2} we find a{sub 2}{sup (p)}=0.077(12) and a{sub 2}{sup (n)}=-0.005(5), where the errors are purely statistical.

  14. Calculation of the {pi}{sup +}{Sigma}{sup +} and {pi}{sup +}{Xi}{sup 0} Scattering Lengths in Lattice QCD

    SciTech Connect

    Torok, Aaron

    2011-10-24

    The {pi}{sup +}{Sigma}{sup +} and {pi}{sup +}{Xi}{sup 0} scattering lengths were calculated in mixed-action Lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations at four light-quark masses, and at two light-quark masses on the fine MILC configurations. Heavy Baryon Chiral Perturbation Theory with two and three flavors of light quarks was used to perform the chiral extrapolations. To NNLO in the three-flavor chiral expansion, the kaon-baryon processes that were investigated show no signs of convergence. Using the two-flavor chiral expansion for extrapolation, the pion-hyperon scattering lengths are found to be a{sub {pi}}{sup +}{sub {Sigma}}{sup +} = -0.197{+-}0.017 fm, and a{sub {pi}}{sup +}{sub {Xi}}{sup 0} = -0.098{+-}0.017 fm, where the comprehensive error includes statistical and systematic uncertainties.

  15. Concerning factors which determine whether flux-lattice shear or pin breaking limits the critical current density of superconductors

    SciTech Connect

    Welch, D.O.

    1992-10-01

    An elementary model is presented which illustrates the conditions under which flux-lattice shear, rather than pin breaking, limits the critical current density. An expression for the shear strength of the flux-lattice, based on the plasticity of metals and alloys, is used to derive the critical current density, including the effect of thermal activation in the flux creep regime.

  16. Concerning factors which determine whether flux-lattice shear or pin breaking limits the critical current density of superconductors

    SciTech Connect

    Welch, D.O.

    1992-01-01

    An elementary model is presented which illustrates the conditions under which flux-lattice shear, rather than pin breaking, limits the critical current density. An expression for the shear strength of the flux-lattice, based on the plasticity of metals and alloys, is used to derive the critical current density, including the effect of thermal activation in the flux creep regime.

  17. Density functional theory for nearest-neighbor exclusion lattice gases in two and three dimensions

    NASA Astrophysics Data System (ADS)

    Lafuente, Luis; Cuesta, José A.

    2003-12-01

    To speak about fundamental measure theory obliges us to mention dimensional crossover. This feature, inherent to the systems themselves, was incorporated in the theory almost from the beginning. Although at first it was thought to be a consistency check for the theory, it rapidly became its fundamental pillar, thus becoming the only density functional theory which possesses such a property. It is straightforward that dimensional crossover connects, for instance, the parallel hard cube system (three dimensional) with that of squares (two dimensional) and rods (one dimensional). We show here that there are many more connections which can be established in this way. Through them we deduce from the functional for parallel hard (hyper)cubes in the simple (hyper)cubic lattice the corresponding functionals for the nearest-neighbor exclusion lattice gases in the square, triangular, simple cubic, face-centered-cubic, and body-centered-cubic lattices. As an application, the bulk phase diagram for all these systems is obtained.

  18. Density-induced geometric frustration of ultra-cold bosons in optical lattices

    NASA Astrophysics Data System (ADS)

    Mishra, T.; Greschner, S.; Santos, L.

    2016-04-01

    A density-dependent gauge field may induce density-induced geometric frustration, leading to a non-trivial interplay between density modulation and frustration, which we illustrate for the particular case of ultra-cold bosons in zig-zag optical lattices with a density-dependent hopping amplitude. We show that the density-induced frustration leads to a rich landscape of quantum phases, including Mott insulator, bond-order insulator, two-component superfluids, chiral superfluids, and partially paired superfluids. We show as well that the density-dependent hopping results in an effective repulsive or attractive interaction, and that for the latter case the vacuum may be destabilized leading to a strong compressibility. Finally, we discuss the characteristic momentum distribution of the predicted phases, which can be used to detect the phases in time-of-flight measurements.

  19. Quantum electrodynamical time-dependent density functional theory for many-electron systems on a lattice

    NASA Astrophysics Data System (ADS)

    Farzanehpour, Mehdi; Tokatly, Ilya; Nano-Bio Spectroscopy Group; ETSF Scientific Development Centre Team

    2015-03-01

    We present a rigorous formulation of the time-dependent density functional theory for interacting lattice electrons strongly coupled to cavity photons. We start with an example of one particle on a Hubbard dimer coupled to a single photonic mode, which is equivalent to the single mode spin-boson model or the quantum Rabi model. For this system we prove that the electron-photon wave function is a unique functional of the electronic density and the expectation value of the photonic coordinate, provided the initial state and the density satisfy a set of well defined conditions. Then we generalize the formalism to many interacting electrons on a lattice coupled to multiple photonic modes and prove the general mapping theorem. We also show that for a system evolving from the ground state of a lattice Hamiltonian any density with a continuous second time derivative is locally v-representable. Spanish Ministry of Economy and Competitiveness (Grant No. FIS2013-46159-C3-1-P), Grupos Consolidados UPV/EHU del Gobierno Vasco (Grant No. IT578-13), COST Actions CM1204 (XLIC) and MP1306 (EUSpec).

  20. Determination of |V(us)|| from a lattice QCD calculation of the K → πℓν semileptonic form factor with physical quark masses.

    PubMed

    Bazavov, A; Bernard, C; Bouchard, C M; Detar, C; Du, Daping; El-Khadra, A X; Foley, J; Freeland, E D; Gámiz, E; Gottlieb, Steven; Heller, U M; Kim, Jongjeong; Kronfeld, A S; Laiho, J; Levkova, L; Mackenzie, P B; Neil, E T; Oktay, M B; Qiu, Si-Wei; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S; Zhou, Ran

    2014-03-21

    We calculate the kaon semileptonic form factor f+(0) from lattice QCD, working, for the first time, at the physical light-quark masses. We use gauge configurations generated by the MILC Collaboration with Nf = 2 + 1 + 1 flavors of sea quarks, which incorporate the effects of dynamical charm quarks as well as those of up, down, and strange. We employ data at three lattice spacings to extrapolate to the continuum limit. Our result, f+(0) = 0.9704(32), where the error is the total statistical plus systematic uncertainty added in quadrature, is the most precise determination to date. Combining our result with the latest experimental measurements of K semileptonic decays, one obtains the Cabibbo-Kobayashi-Maskawa matrix element |V(us)| = 0.22290(74)(52), where the first error is from f+(0) and the second one is from experiment. In the first-row test of Cabibbo-Kobayashi-Maskawa unitarity, the error stemming from |V(us)| is now comparable to that from |V(ud)|. PMID:24702353

  1. Interactions of Charmed Mesons with Light Pseudoscalar Mesons from Lattice QCD and Implications on the Nature of the D*s0(2317)

    SciTech Connect

    Liuming, Liu; Orginos, Kostas; Guo, Feng-Kun; Hanhart, Christoph; Meissner, Ulf-G

    2014-11-01

    We study the scattering of light pseudoscalar mesons ( p , K ) off charmed mesons ( D , D s ) in full lattice QCD. The S -wave scattering lengths are calculated using Luscher’s finite volume technique. We use a relativistic formulation for the charm quark. For the light quark, we use domain- wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We calculate the scattering lengths of isospin-3/2 Dπ , D sπ , D s K , isospin-0 DK and isospin-1 DK channels on the lattice. For the chiral extrapolation, we use a chiral unitary approach to next-to-leading order, which at the same time allows us to give predictions for other channels. It turns out that our results support the interpretation of the D*s0( 2317 ) as a DK molecule. At the same time, we also update a prediction for the isospin breaking hadronic decay width G ( D*s0( 2317 )→ D sπ ) to ( 133± 22 ) keV.

  2. Analyticity of the density of states in the anderson model on the Bethe lattice

    NASA Astrophysics Data System (ADS)

    Acosta, Victor; Klein, Abel

    1992-10-01

    Let H=1/2 Δ+V on l2( B), where B is the Bethe lattice and V(x),xɛ B, are i.i.d.r.v.'s with common probability distribution μ. It is shown that for distributions sufficiently close to the Cauchy distribution, the density of states ρ(E) is analytic in a strip about the real axis.

  3. The phase structure of lattice QCD with two flavors of Wilson quarks and renormalization group improved gluons

    NASA Astrophysics Data System (ADS)

    Farchioni, F.; Jansen, K.; Montvay, I.; Scholz, E.; Scorzato, L.; Shindler, A.; Ukita, N.; Urbach, C.; Wetzorke, I.

    2005-07-01

    The effect of changing the lattice action for the gluon field on the recently observed [F. Farchioni, R. Frezzotti, K. Jansen, I. Montvay, G.C. Rossi, E. Scholz, A. Shindler, N. Ukita, C. Urbach, I. Wetzorke, Eur. Phys. J. C 39, 421 (2005); hep-lat/0406039] first order phase transition near zero quark mass is investigated by replacing the Wilson plaquette action by the DBW2 action. The lattice action for quarks is unchanged: it is in both cases the original Wilson action. It turns out that Wilson fermions with the DBW2 gauge action have a phase structure where the minimal pion mass and the jump of the average plaquette are decreased, when compared to Wilson fermions with Wilson plaquette action at similar values of the lattice spacing. Taking the DBW2 gauge action is advantageous also from the point of view of the computational costs of numerical simulations.

  4. Kaon to Two Pions decays from Lattice QCD: Delta I = 1/2 rule and CP violation

    NASA Astrophysics Data System (ADS)

    Liu, Qi

    We report a direct lattice calculation of the K to pipi decay matrix elements for both the DeltaI=1/2 and 3/2 amplitudes A0 and A2 on a 2+1 flavor, domain wall fermion, 163x32x16 lattice ensemble and a 243x64x16 lattice ensemble. This is a complete calculation in which all contractions for the required ten, four-quark operators are evaluated, including the disconnected graphs in which no quark line connects the initial kaon and final two-pion states. These lattice operators are non-perturbatively renormalized using the Rome-Southampton method and the quadratic divergences are studied and removed. This is an important but notoriously difficult calculation, requiring high statistics on a large volume. In this work we take a major step towards the computation of the physicalK→pipi amplitudes by performing a complete calculation at unphysical kinematics with pions of mass 422 MeV and 329 MeV at rest in the kaon rest frame. With this simplification we are able to resolve Re(A0) from zero for the first time, with a 25% statistical error on the 163 lattice and 15% on the 243 lattice. The complex amplitude A2 is calculated with small statistical errors. We obtain the DeltaI=1/2 rule with an enhancement factor of 9.1(21) and 12.0(17) on these two ensembles. From the detailed analysis of the results we gain a deeper understanding of the origin of the DeltaI=1/2 rule. We also calculate the complex amplitude A0, a calculation central to understanding and testing the standard model of CP violation in the kaon system. The final result for the measure of direct CP violation, epsilon', calculated at unphysical kinematics has an order of 100% statistical error, so this only serves as an order of magnitude check.

  5. Renormalization of quark propagator, vertex functions, and twist-2 operators from twisted-mass lattice QCD at Nf=4

    NASA Astrophysics Data System (ADS)

    Blossier, Benoît.; Brinet, Mariane; Guichon, Pierre; Morénas, Vincent; Pène, Olivier; Rodríguez-Quintero, Jose; Zafeiropoulos, Savvas

    2015-06-01

    We present a precise nonperturbative determination of the renormalization constants in the mass independent RI'-MOM scheme. The lattice implementation uses the Iwasaki gauge action and four degenerate dynamical twisted-mass fermions. The gauge configurations are provided by the ETM Collaboration. Renormalization constants for scalar, pseudoscalar, vector and axial operators, as well as the quark propagator renormalization, are computed at three different values of the lattice spacing, two volumes and several twisted-mass parameters. The method we developed allows for a precise cross-check of the running, thanks to the particular proper treatment of hypercubic artifacts. Results for the twist-2 operator O44 are also presented.

  6. Λb→p ℓ-ν¯ ℓ and Λb→Λcℓ-ν¯ ℓ form factors from lattice QCD with relativistic heavy quarks

    NASA Astrophysics Data System (ADS)

    Detmold, William; Lehner, Christoph; Meinel, Stefan

    2015-08-01

    Measurements of the Λb→p ℓ-ν¯ ℓ and Λb→Λcℓ-ν¯ ℓ decay rates can be used to determine the magnitudes of the Cabibbo-Kobayashi-Maskawa matrix elements Vu b and Vc b, provided that the relevant hadronic form factors are known. Here we present a precise calculation of these form factors using lattice QCD with 2 +1 flavors of dynamical domain-wall fermions. The b and c quarks are implemented with relativistic heavy-quark actions, allowing us to work directly at the physical heavy-quark masses. The lattice computation is performed for six different pion masses and two different lattice spacings, using gauge-field configurations generated by the RBC and UKQCD Collaborations. The b →u and b →c currents are renormalized with a mostly nonperturbative method. We extrapolate the form factor results to the physical pion mass and the continuum limit, parametrizing the q2 dependence using z expansions. The form factors are presented in such a way as to enable the correlated propagation of both statistical and systematic uncertainties into derived quantities such as differential decay rates and asymmetries. Using these form factors, we present predictions for the Λb→p ℓ-ν¯ℓ and Λb→Λc ℓ-ν¯ℓ differential and integrated decay rates. Combined with experimental data, our results enable determinations of |Vu b|, |Vc b|, and |Vu b/Vc b| with theory uncertainties of 4.4%, 2.2%, and 4.9%, respectively.

  7. B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

    SciTech Connect

    Christ, Norman H.; Flynn, Jonathan M.; Izubuchi, Taku; Kawanai, Taichi; Lehner, Christoph; Soni, Amarjit; Van de Water, Ruth S.; Witzel, Oliver

    2015-03-10

    We calculate the B-meson decay constants fB, fBs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as Mπ ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(αsa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain fB0 = 196.2(15.7) MeV, fB+ = 195.4(15.8) MeV, fBs = 235.4(12.2) MeV, fBs/fB0 = 1.193(59), and fBs/fB+ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.

  8. Density-induced processes in quantum gas mixtures in optical lattices

    NASA Astrophysics Data System (ADS)

    Jürgensen, Ole; Sengstock, Klaus; Lühmann, Dirk-Sören

    2012-10-01

    We show that off-site processes and multiorbital physics have a crucial impact on the phase diagram of quantum gas mixtures in optical lattices. In particular, we discuss Bose-Fermi mixtures where the intra- and interspecies interactions induce competing density-induced hopping processes, the so-called bond-charge interactions. Furthermore, higher bands strongly influence tunneling and on-site interactions. We apply a multiorbital interaction-induced dressing of the lowest band, which leads to renormalized hopping processes. These corrections give rise to an extended Hubbard model with intrinsically occupation-dependent parameters. The resulting decrease of the tunneling competes with a decrease of the total on-site interaction energy, both affecting the critical lattice depth of the superfluid to Mott-insulator transition. In contrast to the standard Bose-Fermi Hubbard model, we predict a large shift of the transition to shallower lattice depths with increasing Bose-Fermi attraction. The applied theoretical model allows an accurate prediction of the modified tunneling amplitudes and the critical lattice depth, both being recently observed experimentally.

  9. Unquenched B meson decay constants and neutral B meson-antineutral B meson mixing parameters from chiral lattice QCD

    NASA Astrophysics Data System (ADS)

    Loktik, Oleg

    In this thesis, we present the first 2+1 dynamical flavor lattice calculation of the B meson decay constants, fBd and fBs , as well as B0 - B0 mixing parameters in the infinite heavy quark mass limit. We use the chirality-preserving domain-wall formulation for light quarks. We employ an improved lattice formulation of the static approximation for heavy quarks and the Iwasaki gauge action for gluons. An important part of this thesis is the perturbative calculation which relates lattice operators to their continuum counterparts in the MS(NDR) scheme. This calculation had not been done previously for the aforementioned choice of lattice action, and it is discussed in detail in this thesis. Combining our numerical work with the results of the perturbative calculation, we obtain fstatBd = 231(10) +18-23 MeV, fstatBs = 261(10)(22) MeV, and for the mixing parameters, fstatBd BstatBd mb = 237(13) +19-26 MeV, fstatBs BstatBs mb = 262(12)(22) MeV, and xi ( fstatBs BstatBs )/( fstatBd BstatBd ) = 1.11(7) +13-4 , where the first error is statistical and the second is systematic.

  10. Analysis of average density difference effect in a new two-lane lattice model

    NASA Astrophysics Data System (ADS)

    Zhang, Geng; Sun, Di-Hua; Zhao, Min; Liu, Wei-Ning; Cheng, Sen-Lin

    2015-11-01

    A new lattice model is proposed by taking the average density difference effect into account for two-lane traffic system according to Transportation Cyber-physical Systems. The influence of average density difference effect on the stability of traffic flow is investigated through linear stability theory and nonlinear reductive perturbation method. The linear analysis results reveal that the unstable region would be reduced by considering the average density difference effect. The nonlinear kink-antikink soliton solution derived from the mKdV equation is analyzed to describe the properties of traffic jamming transition near the critical point. Numerical simulations confirm the analytical results showing that traffic jam can be suppressed efficiently by considering the average density difference effect for two-lane traffic system.

  11. QCD In Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Wilczek, Frank

    Introduction Symmetry and the Phenomena of QCD Apparent and Actual Symmetries Asymptotic Freedom Confinement Chiral Symmetry Breaking Chiral Anomalies and Instantons High Temperature QCD: Asymptotic Properties Significance of High Temperature QCD Numerical Indications for Quasi-Free Behavior Ideas About Quark-Gluon Plasma Screening Versus Confinement Models of Chiral Symmetry Breaking More Refined Numerical Experiments High-Temperature QCD: Phase Transitions Yoga of Phase Transitions and Order Parameters Application to Glue Theories Application to Chiral Transitions Close Up on Two Flavors A Genuine Critical Point! (?) High-Density QCD: Methods Hopes, Doubts, and Fruition Another Renormalization Group Pairing Theory Taming the Magnetic Singularity High-Density QCD: Color-Flavor Locking and Quark-Hadron Continuity Gauge Symmetry (Non)Breaking Symmetry Accounting Elementary Excitations A Modified Photon Quark-Hadron Continuity Remembrance of Things Past More Quarks Fewer Quarks and Reality

  12. QCD at nonzero density and canonical partition functions with Wilson fermions

    SciTech Connect

    Alexandru, Andrei; Wenger, Urs

    2011-02-01

    We present a reduction method for Wilson-Dirac fermions with nonzero chemical potential which generates a dimensionally reduced fermion matrix. The size of the reduced fermion matrix is independent of the temporal lattice extent and the dependence on the chemical potential is factored out. As a consequence the reduced matrix allows a simple evaluation of the Wilson fermion determinant for any value of the chemical potential and hence the exact projection to the canonical partition functions.

  13. Dark energy from QCD

    SciTech Connect

    Urban, Federico R.; Zhitnitsky, Ariel R.

    2010-08-30

    We review two mechanisms rooted in the infrared sector of QCD which, by exploiting the properties of the QCD ghost, as introduced by Veneziano, provide new insight on the cosmological dark energy problem, first, in the form of a Casimir-like energy from quantising QCD in a box, and second, in the form of additional, time-dependent, vacuum energy density in an expanding universe. Based on [1, 2].

  14. Lattice QCD determination of states with spin 5/2 or higher in the spectrum of nucleons

    SciTech Connect

    Stephen Wallace; S. Basak; R. Edwards; George Fleming; J. Juge; A. Lichtl; C. Morningstar; D. Richards; I. Sato

    2006-09-28

    Energies for excited isospin 1/2 states that include the nucleon are computed using quenched, anisotropic lattices. Baryon interpolating field operators that are used include nonlocal operators that provide G{sub 2} irreducible representations of the octahedral group. States with spin 5/2 or higher are identified as degenerate energies that occur in irreducible representations of the octahedral group corresponding to the subduction of the continuum spin.

  15. A holographic model for QCD in the Veneziano limit at finite temperature and density

    NASA Astrophysics Data System (ADS)

    Alho, T.; Järvinen, M.; Kajantie, K.; Kiritsis, E.; Rosen, C.; Tuominen, K.

    2014-04-01

    A holographic model of QCD in the limit of large number of colors, N c , and massless fermion flavors, N f , but constant ratio x f = N f /N c is analyzed at finite temperature and chemical potential. The five dimensional gravity model contains three bulk fields: a scalar dilaton sourcing Tr F 2, a scalar tachyon dual to and a 4-vector dual to the baryon current γ μ q. The main result is the μ, T phase diagram of the holographic theory. A first order deconfining transition along T h ( μ) and a chiral transition at T χ ( μ) > T h ( μ) are found. The chiral transition is of second order for small μ and becomes of first order at larger μ. The two regimes are separated by a tricritical point. The dependence of thermodynamical quantities including the speed of sound and susceptibilities on the chemical potential and temperature is computed. A new quantum critical regime is found at zero temperature and finite chemical potential. It is controlled by an AdS2 × R 3 geometry and displays semi-local criticality.

  16. Nature of the Roberge-Weiss transition end points in two-flavor lattice QCD with Wilson quarks

    NASA Astrophysics Data System (ADS)

    Wu, Liang-Kai; Meng, Xiang-Fei

    2013-05-01

    We make simulations with 2 flavor Wilson fermions to investigate the nature of the end points of Roberge-Weiss (RW) first order phase transition lines. The simulations are carried out at 9 values of the hopping parameter κ ranging from 0.155 to 0.198 on different lattice spatial volume. The Binder cumulants, susceptibilities, and reweighted distributions of the imaginary part of the Polyakov loop are employed to determine the nature of the end points of RW transition lines. The simulations show that the RW end points are of first order at the values of κ in our simulations.

  17. Liquid polymorphism and density anomaly in a three-dimensional associating lattice gas.

    PubMed

    Girardi, Mauricio; Balladares, Aline L; Henriques, Vera B; Barbosa, Marcia C

    2007-02-14

    The authors investigate the phase diagram of a three-dimensional associating lattice gas (ALG) model. This model combines orientational icelike interactions and "van der Waals" that might be repulsive, representing, in this case, a penalty for distortion of hydrogen bonds. These interactions can be interpreted as two competing distances, making the connection between this model and continuous isotropic soft-core potentials. The authors present Monte Carlo studies of the ALG model showing the presence of two liquid phases, two critical points, and density anomaly. PMID:17313225

  18. Orientational Relaxation in a Random Dipolar Lattice: Role of Spatial Density Fluctuations in Supercooled Liquids

    NASA Astrophysics Data System (ADS)

    Ravichandran, S.; Bagchi, Biman

    1996-01-01

    We have carried out a computer ``experiment'' of orientational relaxation in a spatially random and orientationally disordered dipolar lattice (RDL), generated by quenching only the translational motion of a dense liquid. In the high polarity limit, the orientational relaxation of the RDL is dramatically different from that of the parent liquid, the former exhibits a very slow, nonexponential long time decay of the orientational correlation functions and markedly non-Debye dielectric relaxation. These results clearly demonstrate the importance of spatial density fluctuations in orientational relaxation.

  19. Local-density approximation for confined bosons in an optical lattice

    SciTech Connect

    Bergkvist, Sara; Henelius, Patrik; Rosengren, Anders

    2004-11-01

    We investigate local and global properties of the one-dimensional Bose-Hubbard model with an external confining potential, describing an atomic condensate in an optical lattice. Using quantum Monte Carlo techniques we demonstrate that a local-density approximation, which relates the unconfined and the confined model, yields quantitatively correct results in most of the interesting parameter range. We also examine claims of universal behavior in the confined system, and demonstrate the origin of a previously calculated fine structure in the experimentally accessible momentum distribution.

  20. One-baryon spectrum and analytical properties of one-baryon dispersion curves in 3 + 1 dimensional strongly coupled lattice QCD with three flavors

    NASA Astrophysics Data System (ADS)

    Faria da Veiga, Paulo A.; O'Carroll, Michael; Valencia Alvites, José C.

    2016-03-01

    Considering a 3 + 1 dimensional lattice quantum chromodynamics (QCD) model defined with the improved Wilson action, three flavors, and 4 × 4 Dirac spin matrices, in the strong coupling regime, we reanalyze the question of the existence of the eightfold way baryons and complete our previous work where the existence of isospin octet baryons was rigorously solved. Here, we show the existence of isospin decuplet baryons which are associated with isolated dispersion curves in the subspace of the underlying quantum mechanical Hilbert space with vectors constructed with an odd number of fermion and antifermion basic quark and antiquark fields. Moreover, smoothness properties for these curves are obtained. The present work deals with a case for which the traditional method to solve the implicit equation for the dispersion curves, based on the use of the analytic implicit function theorem, cannot be applied. We do not have only one but two solutions for each one-baryon decuplet sector with fixed spin third component. Instead, we apply the Weierstrass preparation theorem, which also provides a general method for the general degenerate case. This work is completed by analyzing a spectral representation for the two-baryon correlations and providing the leading behaviors of the field strength normalization and the mass of the spectral contributions with more than one-particle. These are needed results for a rigorous analysis of the two-baryon and meson-baryon particle spectra.