Baryon transport and the QCD critical point

TL;DR

This paper investigates how baryon diffusion in relativistic heavy-ion collisions interacts with the QCD critical point, revealing its insensitivity to critical effects and exploring implications for understanding the phase diagram.

Contribution

It introduces a (1+1)-D model to study the impact of baryon diffusion and critical dynamics on the evolution trajectories in the QCD phase diagram.

Findings

Baryon diffusion shows insensitivity to critical effects.

Trajectories of fluid cells vary across rapidities.

Critical dynamics influence phase diagram trajectories.

Abstract

Fireballs created in relativistic heavy-ion collisions at different beam energies have been argued to follow different trajectories in the QCD phase diagram in which the QCD critical point serves as a landmark. Using a (1+1)-dimensional model setting with transverse homogeneity, we study the complexities introduced by the fact that the evolution history of each fireball cannot be characterized by a single trajectory but rather covers an entire swath of the phase diagram, with the finally emitted hadron spectra integrating over contributions from many different trajectories. Studying the phase diagram trajectories of fluid cells at different space-time rapidities, we explore how baryon diffusion shuffles them around, and how they are affected by critical dynamics near the QCD critical point. We find a striking insensitivity of baryon diffusion to critical effects. Its origins are analyzed and possible implications discussed.