Arguing on entropic and enthalpic first-order phase transitions in strongly interacting matter

TL;DR

This paper explores how the pattern of isentropes near first-order phase transitions in strongly interacting matter can classify transitions as entropic or enthalpic, with implications for heavy-ion collisions and supernovae.

Contribution

It introduces a sub-classification of first-order phase transitions based on isentrope patterns, distinguishing entropic from enthalpic transitions in QCD and nuclear matter.

Findings

Isentropes serve as a useful guide for classifying phase transitions.

Examples from models show clear distinctions between transition types.

Implications for heavy-ion collisions and supernova dynamics.

Abstract

The pattern of isentropes in the vicinity of a first-order phase transition is proposed as a key for a sub-classification. While the confinement--deconfinement transition, conjectured to set in beyond a critical end point in the QCD phase diagram, is often related to an entropic transition and the apparently settled gas-liquid transition in nuclear matter is an enthalphic transition, the conceivable local isentropes w.r.t.\ "incoming" or "outgoing" serve as another useful guide for discussing possible implications, both in the presumed hydrodynamical expansion stage of heavy-ion collisions and the core-collapse of supernova explosions. Examples, such as the quark-meson model and two-phase models, are shown to distinguish concisely the different transitions.