Quark number susceptibilities at finite chemical potential from fugacity expansion

TL;DR

This paper investigates quark number susceptibilities at finite chemical potential in QCD using a fugacity expansion to overcome complex action issues, providing new lattice results up to fourth order and comparing them with models.

Contribution

It introduces a fugacity expansion method to compute generalized quark number susceptibilities at finite chemical potential in lattice QCD.

Findings

Computed susceptibilities up to 4th order at finite mu

Compared lattice results with model calculations

Demonstrated feasibility of fugacity expansion approach

Abstract

Generalized quark number susceptibilities are expected to be good probes for the phase transitions in QCD and the search of a possible critical point. However, their computation in lattice QCD is plagued by the complex action problem which appears at finite chemical potential mu. In this work we explore the possibilities of an expansion in the fugacity parameter exp(mu beta) which has features that make, in particular quark number related bulk observables easily accessible. We present results at finite chemical potential for generalized susceptibilities up to the 4th order as well as their ratios and compare them to model calculations.