Coulomb effect in Au+Au and Pb+Pb collisions as a function of collision energy

TL;DR

This paper investigates how Coulomb interactions influence positive and negative pion spectra in heavy-ion collisions across various energies, revealing energy-dependent trends in Coulomb potential and initial pion ratios.

Contribution

It introduces a systematic analysis of Coulomb effects on pion spectra across multiple collision energies, providing new insights into the nuclear interaction region in heavy-ion collisions.

Findings

Coulomb potential $V_C$ varies with collision energy.

Initial pion ratio $R_i$ shows energy dependence.

Trends in $V_C$ and $R_i$ inform nuclear interaction characteristics.

Abstract

The subtle differences between positive and negative pion spectra can used be used to study the nature of the nuclear interaction region in heavy-ion collisions. Several large acceptance heavy ion experiments at facilities ranging from SIS, the AGS, the SPS, to RHIC have measured mid-rapidity $\pi^+$ and $\pi^-$ spectra for central Au+Au or Pb+Pb collisions. From these spectra one can create pion ratios as a function of $m_t-m_0$, which are used to determine the Coulomb potential, $V_C$, and the initial pion ratio, $R_i$, across a range of collision energies from 1 to 158 AGeV. The implications of the $V_C$ and $R_i$ trends with collision energy will be discussed.