We determine the curvature of the (pseudo)critical line of QCD with nf = 2 + 1 staggered fermions at nonzero temperature and quark density by analytic continuation from imaginary chemical potentials. Monte Carlo simulations are performed by adopting the highly improved staggered quarks /tree action discretization, as implemented in the code by the MILC Collaboration, suitably modified to include a nonzero imaginary baryon chemical potential. We work on a line of constant physics, as determined in Ref. [1], adjusting the couplings so as to keep the strange quark mass ms fixed at its physical value, with a light to strange mass ratio of ml/ms =1/20. In the present investigation, we set the chemical potential at the same value for the three quark species, μl = μs ≡ μ. We explore lattices of different spatial extensions, 16^3 × 6 and 24^3 × 6, to check for finite size effects, and present results on a 32^3 × 8 lattice, to check for finite cutoff effects. We discuss our results for the curvature κ of the (pseudo)critical line at μ = 0, which indicate κ = 0.018(4), and compare them with previous lattice determinations by alternative methods and with experimental determinations of the freeze-out curve.
Critical line of 2 + 1 flavor QCD
CEA, Paolo;
2014-01-01
Abstract
We determine the curvature of the (pseudo)critical line of QCD with nf = 2 + 1 staggered fermions at nonzero temperature and quark density by analytic continuation from imaginary chemical potentials. Monte Carlo simulations are performed by adopting the highly improved staggered quarks /tree action discretization, as implemented in the code by the MILC Collaboration, suitably modified to include a nonzero imaginary baryon chemical potential. We work on a line of constant physics, as determined in Ref. [1], adjusting the couplings so as to keep the strange quark mass ms fixed at its physical value, with a light to strange mass ratio of ml/ms =1/20. In the present investigation, we set the chemical potential at the same value for the three quark species, μl = μs ≡ μ. We explore lattices of different spatial extensions, 16^3 × 6 and 24^3 × 6, to check for finite size effects, and present results on a 32^3 × 8 lattice, to check for finite cutoff effects. We discuss our results for the curvature κ of the (pseudo)critical line at μ = 0, which indicate κ = 0.018(4), and compare them with previous lattice determinations by alternative methods and with experimental determinations of the freeze-out curve.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
