Phase boudaries near critical end points. I. Thermodinamics and universality

Abstract

The vicinity of a criticai end point is analyzed in order to reveal singularities arising in the form of the first-order phase boundary to the noncritical phase. Phenomenological arguments are presented and critically assessed that directly relate the nonanalytic behavior of the phase boundary to universal features of the bulk thermodynamics on the associated criticai line. Explicit values are given for universal amplitude ratios describing the boundary for various types of criticality.