Fourier coefficients of the net-baryon number density and chiral criticality

TL;DR

This paper explores how Fourier coefficients of net-baryon density reveal critical phenomena in QCD matter, linking their behavior to phase transitions and singularities in the complex chemical potential plane.

Contribution

It demonstrates the connection between Fourier coefficients and chiral/deconfinement properties in a QCD-like model, highlighting their potential to probe QCD criticality.

Findings

Fourier coefficients reflect chiral and deconfinement transitions.

Asymptotic behavior linked to singularities in the complex plane.

Roberge-Weiss transition influences Fourier coefficients.

Abstract

We investigate the Fourier coefficients $b_k(T)$ of the net--baryon number density in strongly interacting matter at nonzero temperature and density. The asymptotic behavior of the coefficients at large $k$ is determined by the singularities of the partition function in the complex chemical potential plane. Within a QCD-like effective chiral model, we show that the chiral and deconfinement properties at nonzero baryon chemical potential are reflected in characteristic $k$-- and $T$-- dependences of the Fourier coefficients. We also discuss the influence of the Roberge-Weiss transition on these coefficients. Our results indicate that the Fourier expansion approach can provide interesting insights into the criticality of QCD matter.