Equation of state in (2+1)-flavor QCD

Abstract

We present results for the equation of state in (2+1)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent Nτ = 6, 8, 10, and 12. We show that these data can be reliably extrapolated to the continuum limit and obtain a number of thermodynamic quantities and the speed of sound in the temperature range (130-400) MeV. We compare our results with previous calculations, and provide an analytic parameterization of the pressure, from which other thermodynamic quantities can be calculated, for use in phenomenology. We show that the energy density in the crossover region, 145 MeV ≤ T ≤ 163 MeV, defined by the chiral transition, is c = (0.18 − 0.5) GeV/fm 3 , i.e., (1.2 − 3.1) nuclear . At high temperatures, we compare our results with resummed and dimensionally reduced perturbation theory calculations. As a byproduct of our analyses, we obtain the values of the scale parameters r0 from the static quark potential and w0 from the gradient flow.

Determination ofαsfrom the QCD static energy: An update

“…[5], from the comparison of lattice data with perturbative expressions for the static energy of a heavy quark-antiquark pair. This has been possible because a considerable amount of new lattice data at shorter distances has become available [6], which has allowed us to carry out an extra number of cross checks and hence to considerably reduce the systematic errors. In particular we have been able to correct for cutoff effects in the shorter-distance points, to analyze the dependence on the fit range, and to carry out separate analyses for different lattice spacings.…”

“…One may worry about the evolution of the topological charge on such fine lattices, but, as it was demonstrated in Ref. [6], the Monte-Carlo evolution of the topological charge is acceptable even for β = 7.825. The lattice spacing was fixed using the r 1 scale defined as r 2 dE 0 (r) dr r=r1 = 1.0 .…”

“…The details of the lattice spacing determination, including the error estimates, are presented in Ref. [6], where also additional checks on the lattice spacing determination using different physical observables are performed. Since we are interested in the behavior of the static energy at short distances the effect of finite volume in lattice calculations is negligible.…”

“…In this paper we use 2+1-flavor lattice QCD data on the static quark-antiquark energy, E 0 (r), obtained using tree-level improved gauge action and HighlyImproved Staggered Quark (HISQ) action, procured by the HotQCD collaboration [6]. The strange-quark mass m s was fixed to its physical value, while the light-quark masses were chosen to be m l = m s /20.…”

In-medium P-wave quarkonium from the complex lattice QCD potential

“…Since a collection of intricate features, such as bound state peaks, the open heavy flavor threshold and eventually the lattice cutoff is present in the actual spectrum, its reliable reconstruction from Euclidean data is highly challenging. These difficulties are particularly apparent when using Euclidean data from simulations with realistic light quarks, where currently only a very small number of data points ∼ O(10) are available [56][57][58]. Two groups have recently investigated bottomonium states using Bayesian reconstruction methods in lattice NRQCD at finite temperature [31,32].…”