Beam Energy Scan a Case for the Chiral Magnetic Effect in Au-Au Collisions

TL;DR

This paper presents STAR experiment measurements across various energies in Au-Au collisions, providing evidence that the Chiral Magnetic Effect activates with energy and is absent in central collisions with weaker magnetic fields.

Contribution

It offers new experimental data supporting the energy-dependent emergence of the CME in heavy-ion collisions at RHIC.

Findings

CME signal increases with collision energy

CME is absent in central collisions with small magnetic fields

Experimental evidence supports the energy threshold for CME activation

Abstract

The Chiral Magnetic Effect (CME) is predicted for Au-Au collisions at RHIC. However many backgrounds can give signals that make the measurement hard to interpret. The STAR experiment has made measurements at different collisions energy ranging from $\sqrt{s_{NN}}$=7.7 GeV to 62.4 GeV. In the analysis that is presented we show that the CME turns on with energy and is not present in central collisions where the induced magnetic is small.