Thermodynamics at non-zero baryon number density: a comparison of lattice and hadron resonance gas model calculations

We compare recent lattice studies of QCD thermodynamics at non-zero quark chemical potential with the thermodynamics of a hadron resonance gas. We argue that for T less than or equal to T-c the equation of state derived from Monte Carlo simulations of two flavour QCD at non-zero chemical potential can be well described by a hadron resonance gas when using the same set of approximations as used in current lattice calculations. We estimate the importance of truncation errors arising from the use of a Taylor expansion in terms of the quark chemical potential and examine the influence of unphysically large quark masses oil the equation of state and the critical conditions for deconfinement. (C) 2003 Elsevier B.V. All rights reserved.