We show that universality near a critical end point implies a characteristic relation between third- and fourth-order baryon susceptibilities ${\chi }_3$ and ${\chi }_4$, resulting in a banana-shaped loop when ${\chi }_4$ is plotted as a function of ${\chi }_3$ along a freeze-out line. This result relies only on the derivative relation between ${\chi }_3$ and ${\chi }_4$, the enhancement of the correlation length and the scaling symmetry near a critical point, and the freeze-out line near the critical point not too parallel to the ${\mu }_B$ axis. Including the individual enhancements of ${\chi }_3$ and ${\chi }_4$ near a critical point, these features may be a consistent set of observations supporting the interpretation of baryon fluctuation data as arising from criticality.

• Received 2 April 2016

DOI:https://doi.org/10.1103/PhysRevD.95.014038