Baryon susceptibilities, nongaussian moments and the QCD critical point

Understand

We calculate model-independently the impact of the critical point on higher order baryon susceptibilities $\chi_n$, showing how they depend on fluctuations of the order parameter.

• Including all tree level diagrams, we find new contributions to $\chi_4$ equally important to the kurtosis of the order parameter fluctuations, and we characterize the kurtosis and other nonguassian moments as functions on the phase diagram.
• Important features of this analysis are then confirmed by a Gross-Neveu model study with good agreement with other model studies as well as lattice and experimental data.
• This suggests the universality of the characteristic peak in baryon susceptibilities as a signal of the critical point.