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Phase diagram of QCD with 2+1 flavors of Wilson quarks at finite temperature and chemical potential  [PDF]
He-Sheng Chen,Xiang-Qian Luo
Physics , 2007,
Abstract: The first results on lattice at finite temperature $T$ and chemical potential $\mu$ with 2+1 flavors of Wilson quarks are presented. We have studied the dependence of chiral phase transition and deconfinement phase transition on quark mass. Finite volume size analysis and Binder cumulants are used to determine the properties of phase transition. Phase diagram of QCD with 2+1 flavors of Wilson quarks are presented.
Lattice QCD thermodynamics with Wilson quarks  [PDF]
Shinji Ejiri
Physics , 2007, DOI: 10.1143/PTPS.168.245
Abstract: 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.
QCD thermodynamics with two flavours of Wilson fermions on large lattices  [PDF]
Bastian B. Brandt,Anthony Francis,Harvey B. Meyer,Owe Philipsen,Hartmut Wittig
Physics , 2012,
Abstract: We explore the phase diagram of two flavour QCD at vanishing chemical potential using dynamical O(a)-improved Wilson quarks. In the approach to the chiral limit we use lattices with a temporal extent of N_t=16 and spatial extent L=32,48 and 64 to enable the extrapolation to the thermodynamic limit with small discretisation effects. In addition to an update on the scans at constant \kappa, reported earlier, we present first results from scans along lines of constant physics at a pion mass of 290 MeV. We probe the transition using the Polyakov loop and the chiral condensate, as well as spectroscopic observables such as screening masses.
Effects of dynamical quarks on the spectrum of the Wilson Dirac operator  [PDF]
G. Akemann,P. H. Damgaard,K. Splittorff,J. J. M. Verbaarschot
Physics , 2010,
Abstract: Effects of dynamical quarks on the microscopic spectrum of the Wilson Dirac operator are analyzed by means of effective field theory. We consider the distributions of the real modes of the Wilson Dirac operator as well as the spectrum of the Hermitian Wilson Dirac operator, and work out the case of one flavor in all detail. In contrast to the quenched case, the theory has a mild sign problem that manifests itself by giving a spectral density that is not positive definite as the spectral gap closes.
Hybrid Monte Carlo algorithm for lattice QCD with two flavors of dynamical Ginsparg-Wilson quarks  [PDF]
Chuan Liu
Physics , 1998, DOI: 10.1016/S0550-3213(99)00276-X
Abstract: We study aspects concerning numerical simulations of Lattice QCD with two flavors of dynamical Ginsparg-Wilson quarks with degenerate masses. A Hybrid Monte Carlo algorithm is described and the formula for the fermionic force is derived for two specific implementations. The implementation with optimal rational approximation method is favored both in CPU time and memory consumption.
Numerical simulation with light Wilson-quarks  [PDF]
I. Montvay
Physics , 2003,
Abstract: The computational cost of numerical simulations of QCD with light dynamical Wilson-quarks is estimated by determining the autocorrelation of various quantities. In test runs the expected qualitative behaviour of the pion mass and coupling at small quark masses is observed.
Simulations with dynamical HISQ quarks  [PDF]
A. Bazavov,C. Bernard,C. DeTar,W. Freeman,Steven Gottlieb,U. M. Heller,J. E. Hetrick,J. Laiho,L. Levkova,M. Oktay,J. Osborn,R. L. Sugar,D. Toussaint,R. S. Van de Water
Physics , 2010,
Abstract: We report on the status of a program of generating and using configurations with four flavors of dynamical quarks, using the HISQ action. We study the lattice spacing dependence of physical quantities in these simulations, using runs at several lattice spacings, but with the light quark mass held fixed at two tenths of the strange quark mass. We find that the lattice artifacts in the HISQ simulations are much smaller than those in the asqtad simulations at the same lattice spacings and quark masses. We also discuss methods for setting the scale, or assigning a lattice spacing to ensembles run at unphysical parameters.
The $N_f= 2$ chiral phase transition from imaginary chemical potential with Wilson Fermions  [PDF]
Owe Philipsen,Christopher Pinke
Physics , 2015,
Abstract: The order of the thermal transition in the chiral limit of QCD with two dynamical flavours of quarks is a long-standing issue. Still, it is not definitely known whether the transition is of first or second order in the continuum limit. Which of the two scenarios is realized has important implications for the QCD phase diagram and the existence of a critical endpoint at finite densities. Settling this issue by simulating at successively decreased pion mass was not conclusive yet. Recently, an alternative approach was proposed, extrapolating the first order phase transition found at imaginary chemical potential to zero chemical potential with known exponents, which are induced by the Roberge-Weiss symmetry. For staggered fermions on $N_t=4$ lattices, this results in a first order transition in the chiral limit. Here we report of $N_t=4$ simulations with Wilson fermions, where the first order region is found to be large.
Phase diagram of SU(2) with 2 flavors of dynamical adjoint quarks  [PDF]
Simon Catterall,Joel Giedt,Francesco Sannino,Joe Schneible
Physics , 2008, DOI: 10.1088/1126-6708/2008/11/009
Abstract: We report on numerical simulations of SU(2) lattice gauge theory with two flavors of light dynamical quarks in the adjoint of the gauge group. The dynamics of this theory is thought to be very different from QCD -- the theory exhibiting conformal or near conformal behavior in the infrared. We make a high resolution survey of the phase diagram of this model in the plane of the bare coupling and quark mass on lattices of size 8^3 \times 16. Our simulations reveal a line of first order phase transitions extending from beta=0 to beta=beta_c \sim 2.0. For beta > beta_c the phase boundary is no longer first order but continues as the locus of minimum meson mass. For beta > 2.0 we observe the pion and rho masses along the phase boundary to be light, independent of bare coupling and approximately degenerate. We discuss possible interpretations of these observations and corresponding continuum limits.
QCD thermodynamics with O(a) improved Wilson fermions at Nf=2  [PDF]
Bastian B. Brandt,Anthony Francis,Harvey B. Meyer,Owe Philipsen,Hartmut Wittig
Physics , 2013,
Abstract: We present an update of our study of the phase diagram of two-flavour QCD at zero baryon density with dynamical $O(a)$ improved Wilson quarks. All simulations are done on lattices with a temporal extent of $N_t=16$ and spatial extent $L=32,48$ and 64, ensuring that discretisation effects are small and finite size effects can be controlled. In the approach to the chiral limit we currently have three scans with pion masses between 540 and 200 MeV. In this proceedings article the focus is on the new scan at $m_\pi=200$ MeV and the measurement of screening masses. We also present first results concerning a test of scaling in the approach to the chiral limit and the chiral extrapolation of the difference of screening masses in scalar and pseudoscalar channels, which provides a measure for the strength of the anomalous breaking of the $U_A(1)$ symmetry.
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