Simple patterns for non-linear susceptibilities near T_c

TL;DR

This paper constructs higher-order non-linear susceptibilities in QCD with dynamical quarks, revealing peaks at the crossover temperature T_c and identifying simple topological contributions that any effective theory must explain.

Contribution

It introduces calculations of non-linear susceptibilities up to eighth order in QCD with dynamical quarks and highlights their simple topological structure near T_c.

Findings

Susceptibilities peak at T_c

Dominant contributions have simple topology

Effective theories must account for these regularities

Abstract

Non-linear susceptibilities upto the eighth order have been constructed in QCD with 2 flavours of dynamical quarks. Beyond leading order, they exhibit peaks at the cross over temperature, T_c. By analyzing their behaviour in detail, we find that the dominant contributions near T_c come from a set of operators with a remarkably simple topology. Any effective theory of QCD near T_c must be able to explain these regularities.