Exploring the QCD phase diagram via reweighting from isospin chemical potential

Abstract

We investigate the QCD phase diagram for small values of baryon and strange quark chemical potentials from simulations at non-zero isospin chemical potential. Simulations at pure isospin chemical potential are not hindered by the sign problem and pion condensation can be observed for sufficiently large isospin chemical potentials. We study how the related phase boundary evolves with baryonic and strange chemical potentials via reweighting in quark chemical potentials and discuss our results. Furthermore, we propose and implement an alternative method to approach nonzero baryon (and strange quark) chemical potentials. This method involves simulations where physical quarks are paired with auxiliary quarks in unphysical "isospin" doublets and a decoupling of the auxiliary quarks by mass reweighting.