Coulomb Interaction Effects on Pion Production in Au+Au Collisions at Relativistic Energies

Catalin Ristea,Oana Ristea,Alexandru Jipa

doi:10.1155/2018/3865856

Catalin Ristea, Oana Ristea + Show 1 more

Open Access

https://doi.org/10.1155/2018/3865856

Copy DOI

Abstract

Coulomb effects on charged pion transverse momentum spectra measured in Au+Au collisions at RHIC-BES energies are investigated. From these spectra the π-/π+ ratios as a function of transverse momentum are obtained and used to extract the “Coulomb kick”, pc (a momentum change due to the Coulomb interaction), and initial pion ratio for three different collision energies and various centrality classes. The Coulomb kick shows a decrease with the increase of beam energy and a clear centrality dependence, with larger values for the most central collisions. The results are connected with the kinetic freeze-out dynamics.

Highlights

One of the main goals of studying heavy-ion collisions at relativistic energies is to characterize the nuclear matter at extreme energy densities and temperatures
We present an analysis of the Coulomb effects on charged pion production in Au+Au collisions at RHIC-Beam Energy Scan program (BES) energies based on an analytic model developed in [15, 16]
In order to extract information related to the Coulomb interaction between the produced particles we analyzed the charged pion transverse momentum spectra produced in Au+Au collisions at √sNN = 7.7, 11.5, and 19.6 GeV and measured by the STAR experiment [17]

Summary

Introduction

One of the main goals of studying heavy-ion collisions at relativistic energies is to characterize the nuclear matter at extreme energy densities and temperatures. In heavy-ion collisions at SIS [1, 2], AGS [3,4,5], and SPS [6,7,8] energies, the transverse momentum spectra of positively and negatively charged pions show a difference in shape at low pT and these results were interpreted as due to the Coulomb final-state interaction between the charged pions and the positive net-charge of the particle source. The charged pions, as the most abundantly produced and lightest species, are the particles most strongly influenced by the Coulomb field. They are accelerated or decelerated and their final (detected) momentum is changed.

Results

Conflicts of Interest

Conclusions