QCD phase diagram with isospin chemical potential

TL;DR

This paper explores the QCD phase diagram with isospin chemical potential, introducing a pionic source to address infrared issues, and compares different extrapolation methods to determine phase boundaries and transition temperatures.

Contribution

It presents a novel approach using the singular value spectrum of the Dirac operator to extrapolate results to zero pionic source, enhancing understanding of QCD phase transitions.

Findings

Identified the phase transition boundary between normal and pion condensation phases.

Determined the chiral/deconfinement transition temperature as a function of chemical potential.

Compared direct results with Taylor-expansion to evaluate its applicability range.

Abstract

In this contribution we investigate the phase diagram of QCD in the presence of an isospin chemical potential. To alleviate the infrared problems of the theory associated with pion condensation, we introduce the pionic source as an infrared regulator. We discuss various methods to extrapolate the results to vanishing pionic source, including a novel method based on the singular value spectrum of the massive Dirac operator, a leading-order reweighting and a spline Monte-Carlo fit. Our main results concern the phase transition boundary between the normal and the pion condensation phases and the chiral/deconfinement transition temperature as a function of the chemical potential. In addition, we perform a quantitative comparison between our direct results and a Taylor-expansion obtained at zero chemical potential to assess the applicability range of the latter.