Baryon Stopping in Heavy-Ion Collisions at E_{lab}= 2--160 GeV/nucleon

TL;DR

The paper investigates baryon stopping in heavy-ion collisions across a range of energies, suggesting a non-monotonous energy dependence that may indicate a phase transition, with models including a quark-gluon phase transition better reproducing observed irregularities.

Contribution

It demonstrates that a first-order phase transition in the equation of state can qualitatively explain the non-monotonous baryon stopping behavior observed experimentally.

Findings

Non-monotonous 'zig-zag' pattern in baryon stopping as a function of collision energy.

Hadronic EoS models fail to reproduce the irregularity.

EoS with a phase transition qualitatively reproduces the irregularity.

Abstract

It is argued that the experimentally observed baryon stopping may indicate (within the present experimental uncertainties) a non-monotonous behaviour as a function of the incident energy of colliding nuclei. This can be quantified by a midrapidity reduced curvature of the net-proton rapidity spectrum. The above non-monotonous behaviour reveals itself as a "zig-zag" irregularity in the excitation function of this curvature. The three-fluid dynamic calculations with a hadronic equation of state (EoS) fail to reproduce this irregularity. At the same time, the same calculations with an EoS involving a first-order phase transition into the quark-gluon phase do reproduce this "zig-zag" behaviour, however only qualitatively.