Staggered Fermion Thermodynamics using Anisotropic Lattices (original) (raw)

Two-flavor QCD thermodynamics using anisotropic lattices

Physical Review D, 2006

Numerical simulations of full QCD on anisotropic lattices provide a convenient way to study QCD thermodynamics with fixed physics scales and reduced lattice spacing errors. We report results from calculations with two flavors of dynamical staggered fermions, where all bare parameters and the renormalized anisotropy are kept constant and the temperature is changed in small steps by varying only the number of time slices. Including results from zero-temperature scale setting simulations, which determine the Karsch coefficients, allows for the calculation of the equation of state at finite temperatures.

Lattice QCD thermodynamic results with improved staggered fermions

European Physical Journal C Particles and Fields, 2009

We present results on the QCD equation of state, obtained with two different improved dynamical staggered fermion actions and almost physical quark masses. Lattice cut-off effects are discussed in detail as results for three different lattice spacings are available now, i.e. results have been obtained on lattices with temporal extent of N τ =4,6 and 8. Furthermore we discuss the Taylor expansion approach to non-zero baryon chemical potential and present the isentropic equation of state on lines of constant entropy per baryon number.

Anisotropic lattices and dynamical fermions

Nucl Phys B Proc Suppl, 2001

We report results from full QCD calculations with two flavors of dynamical staggered fermions on anisotropic lattices. The physical anisotropy as determined from spatial and temporal masses, their corresponding dispersion relations, and spatial and temporal Wilson loops is studied as a function of the bare gauge anisotropy and the bare velocity of light appearing in the Dirac operator. The anisotropy dependence of staggered fermion flavor symmetry breaking is also examined. These results will then be applied to the study of 2-flavor QCD thermodynamics.

QCD thermodynamics with an improved lattice action

Physical Review D, 1997

We have investigated QCD with two flavors of degenerate fermions using a Symanzik-improved lattice action for both the gauge and fermion actions. Our study focuses on the deconfinement transition on an Nt=4N_t=4Nt=4 lattice. Having located the thermal transition, we performed zero temperature simulations nearby in order to compute hadronic masses and the static quark potential. We find that the present action reduces lattice artifacts present in thermodynamics with the standard Wilson (gauge and fermion) actions. However, it does not bring studies with Wilson-type quarks to the same level as those using the Kogut--Susskind formulation.

Determining the nature of the finite temperature transition of QCD with dynamical fermions

Nuclear Physics B, 1990

Numerical results are presented for lattice QCD with m = 0.1 four-flavour staggered fermions around the finite-temperature transition at /3 5.13 on a i0 3 x 4 volume using the Hybrid Monte Carlo. A method is described that extends the /3 range that can be analysed using data gathered at only one /3 value. The nature of the order of the transition at m 0.1 is discussed using results from 6~x 4-10~x 4 volumes. Over this range, a standard test indicates that the data are more consistent with a sharp crossover and shows that the first-order transition, when it develops on larger lattices, must be rather weak.

Dynamical fermions on anisotropic lattices

Nuclear Physics B-proceedings Supplements, 2003

We report on our study of two-flavor full QCD on anisotropic lattices using O(a)-improved Wilson quarks coupled with an RG-improved glue. The bare gauge and quark anisotropies corresponding to the renormalized anisotropy ξ = as/at = 2 are determined as functions of β and κ, using the Wilson loop and the meson dispersion relation at several lattice cutoffs and quark masses.

Dynamical QCD thermodynamics with domain wall fermions

Nuclear Physics B - Proceedings Supplements, 1999

We present results from numerical simulations of full, two flavor QCD thermodynamics at Nt = 4 with domain wall fermions. For the first time a numerical simulation of the full QCD phase transition displays a low temperature phase with spontaneous chiral symmetry breaking but intact flavor symmetry and a high temperature phase with the full SU (2) × SU (2) chiral flavor symmetry.

Lattice QCD thermodynamics on the Grid

Computer Physics Communications, 2010

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