Bonn 2010 – wissenschaftliches Programm
HK 14.2: Gruppenbericht
Dienstag, 16. März 2010, 14:30–15:00, HG I
Can we locate the QCD critical endpoint by Taylor expansion? — Frithjof Karsch1,2,3, Bernd-Jochen Schaefer4, •Mathias Wagner5, and Jochen Wambach3,5 — 1Universität Bielefeld, 33615 Bielefeld — 2Brookhaven National Laboratory, Upton, NY 11973, USA — 3Gesellschaft für Schwerionenforschung GSI, 64291 Darmstadt — 4Universität Graz, A-8010 Graz, Austria — 5TU Darmstadt, 64289 Darmstadt
The existence and location of a critical endpoint in the QCD phase diagram is still an open question. Studies in chiral effective models yield a strong parameter dependence of its existence and location. While lattice studies at finite temperature continue to improve, they still suffer from the sign problem at finite density. One approach to access at least small densities in the phase diagram is based on Taylor expansion.
In this talk the convergence properties of the Taylor expansion and
their relation to the phase boundary and critical endpoint will be
addressed. With a novel numerical technique  the expansion
coefficients are calculated up to 24th order  in a
2+1-flavor Polyakov-quark-meson model . The knowledge of higher
order coefficients and the evaluation of the model at finite density
allow a detailed benchmark of the method.
 M. Wagner et. al., arXiv:0912.2208 [hep-ph].
 B.-J. Schaefer at al., PoS CPOD 2009 017.
 B.-J. Schaefer et al., arXiv:0910.5628 [hep-ph].