Susceptibilities, the Specific Heat and a Cumulant in Two-Flavour QCD

TL;DR

This study investigates how quark mass influences response functions like susceptibilities and specific heat in two-flavour QCD, providing insights into critical exponents and confirming a second order phase transition.

Contribution

It offers a detailed analysis of quark mass dependence of response functions and introduces a cumulant as a scaling function to determine the critical exponent δ.

Findings

Results are consistent with a second order phase transition.

Calculated critical exponents α, β, δ from response functions.

Constructed a cumulant that directly yields δ.

Abstract

We study the quark mass dependence of various response functions, which contribute to chiral susceptibilities and the specific heat in the staggered fermion formulation of two-flavour QCD. This yields information about the critical exponents $\alpha$, $\beta$ and $\delta$. In the case of the chiral susceptibility, obtained as derivative of the chiral order parameter with respect to the quark mass, we calculate all contributions. This allows to construct a cumulant of the order parameter, which is a scaling function and yields a direct determination of the critical exponent $\delta$. All our results are consistent with a second order phase transition.