Volume dependence of baryon number cumulants and their ratios

Understand

We explore the influence of finite volume effects on baryon number fluctuations in a non-perturbative chiral model.

• In order to account for soft modes, we use the functional renormalization group in a finite volume, using a smooth regulator function in momentum space.
• We compare the results for a smooth regulator with those for a sharp (or Litim) regulator, and show that in a finite volume, the latter produces spurious artifacts.
• In a finite volume there are only apparent critical points, about which we compute the ratio of the fourth to the second order cumulant of quark number fluctuations.