Quartic cumulant of baryon number in the presence of QCD critical point

Understand

In the context of the ongoing search for the QCD critical point at the Relativistic Heavy-Ion Collider, we study the equation of state near the critical point in the temperature and baryon chemical potential plane.

• We use the parametric representation introduced in earlier literature, which maps the universal 3D Ising equation of state onto the QCD phase diagram using several non-universal parameters.
• We focus on the quartic cumulant of the baryon number, or baryon number susceptibility~$\chi_4^B$, which can be accessed experimentally via net-proton fluctuation kurtosis measurements.
• It was originally predicted, through universality arguments based on the {\em leading} singular contribution, that $\chi_4^B$ and net-proton kurtosis should show a specific non-monotonic behavior due to the critical point.