Universal relations between nongaussian fluctuations in heavy-ion collisions

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. 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 fluctuations data as arising from criticality.