Transverse Velocity Dependence of the Proton-Antiproton Ratio as a Signature of the QCD Critical Endpoint

TL;DR

This paper proposes that the transverse velocity dependence of the proton-antiproton ratio can serve as a signature of the QCD critical endpoint, with specific patterns indicating proximity to the critical point.

Contribution

It introduces a novel method to detect the QCD critical point by analyzing the transverse velocity dependence of the proton-antiproton ratio in heavy-ion collisions.

Findings

Unusual $eta_{T}$-dependence of $ar{p}/p$ ratio signals critical point proximity.

Hydrodynamic trajectory deformation affects particle ratio dependence.

Method provides a new experimental signature for the QCD critical endpoint.

Abstract

The presence of a critical point in the QCD phase diagram can deform the trajectories describing the evolution of the expanding fireball in the $\mu_B-T$ phase diagram. If the average emission time of hadrons is a function of transverse velocity, as microscopic simulations of the hadronic freeze-out dynamics suggest, the deformation of the hydrodynamic trajectories will change the transverse velocity ($\beta_{\rm T}$) dependence of the proton-antiproton ratio when the fireball passes in the vicinity of the critical point. An unusual $\beta_{\rm T}$-dependence of the $\bar{p}/p$ ratio in a narrow beam energy window would thus signal the presence of the critical point.