Nuclear Physics Confronts Relativistic Collisions Of Isobars

TL;DR

This paper discusses high-energy isobar collisions at RHIC to investigate the chiral magnetic effect, revealing that observed deviations are mainly due to nuclear structure differences rather than new physics.

Contribution

It combines low-energy nuclear structure insights with high-energy collision data to interpret isobar collision results at RHIC.

Findings

Deviations in collision ratios are caused by nuclear structure differences.

Nuclear deformation impacts observable ratios in isobar collisions.

Collaborative efforts enhance understanding of high-energy nuclear collision data.

Abstract

High-energy collisions involving the $A=96$ isobars $^{96}$Zr and $^{96}$Ru have been performed in 2018 at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) as a means to search for the chiral magnetic effect in QCD. This would manifest itself as specific deviations from unity in the ratio of observables taken between $^{96}$Zr+$^{96}$Zr and $^{96}$Ru+$^{96}$Ru collisions. Measurements of such ratios (released at the end of 2021) indeed reveal deviations from unity, but these are primarily caused by the two collided isobars having different radial profiles and intrinsic deformations. To make progress in understanding RHIC data, nuclear physicists across the energy spectrum gathered in Heidelberg in 2022 as part of an EMMI Rapid Reaction Task Force (RRTF) to address the following question. Does the combined effort of low-energy nuclear structure physics and high-energy heavy-ion physics enable us to understand the observations made in isobar collisions at RHIC?