Equation of state at finite density in two-flavor QCD with improved Wilson quarks

Abstract

We study the equation of state in two-flavor QCD at finite temperature and density. Simulations are made with the RG-improved gluon action and the clover-improved Wilson quark action. Along the lines of constant physics for $m_{\mathrm{PS}}/m_{\mathrm{V}}=0.65$ and 0.80, we compute the derivatives of the quark determinant with respect to the quark chemical potential ${\mu }_q$ up to the fourth order at ${\mu }_q=0$. We adopt several improvement techniques in the evaluation. We study thermodynamic quantities and quark number susceptibilities at finite ${\mu }_q$ using these derivatives. We find enhancement of the quark number susceptibility at finite ${\mu }_q$, in accordance with previous observations using staggered-type quarks. This suggests the existence of a nearby critical point.

Comments: 7 pages, 16 figures, presented at the XXVI International Symposium on Lattice Field Theory (LATTICE 2008), July 14-19, 2008, Williamsburg, Virginia, USA