Exploring the QCD phase diagram
Owe Philipsen
Abstract
The last
few years have seen a lot of activity in determining the QCD phase diagram by
lattice simulations, for Nf=2,3,4
as well as physical QCD, and for zero and non-zero baryon density. The questions of interest are the
location, order and universality class of the quark-hardon
transition as a function of the parameters of the theory. Considerable progress
was made in developing methods to simulate at finite density. However, recent investigations
also point to the important role systematic errors are playing in dynamical
simulations with current available resources, and how sensitive the phase
diagram is to such errors. As a
result, it turns out that even the qualitative features of the QCD phase
diagram cannot be regarded as settled yet.