Recent results of CME search from isobar and AuAu collisions at RHIC

Relativistic heavy ion collisions serve as a unique testing ground for Quantum Chromodynamics (QCD) at high energies, generating the densest known matter and the strongest electromagnetic fields. Among the phenomena observed, the Chiral Magnetic Effect (CME) arises from the violation of local P and CP symmetries in the presence of strong fields. It is associated with the creation of an electric current along the direction of magnetic field -- leading to the separation of positively and negatively charged particles across the plane determined by the impact parameter and collision directions of the two heavy ions. Signatures of CME have been extensively searched in heavy ion collisions. However, most of the previous measurements of the CME have been inconclusive due to significant background contributions. To overcome this challenge, the STAR collaboration conducted a blind analysis on a large dataset comprising approximately 3.8 billion isobar Ru+Ru and Zr+Zr collisions at a center-of-mass energy of 200 GeV at the Relativistic Heavy Ion Collider in the year 2018. This analysis aimed to better control the influence of signal and backgrounds, providing more robust insights into the CME. In this presentation, I provide a brief historical overview of the search for the CME in HICs and discuss the findings obtained from the blind analysis of the isobar data.

Additionally, I will explore the future directions of CME research in heavy ion collisions, building upon the success of the isobar program. Promising avenues include the analysis of high-statistics data from the second phase of the RHIC beam energy scan program using new detector upgrades of the STAR experiment. Such an initiative offers unique opportunities to investigate the collision energy dependence of CME. Additionally, the anticipated run of RHIC in the years 2023-2025, coupled with innovative analysis techniques, provides a chance to extract upper limits on the observability of the CME in Au+Au collisions.

The implications of CME search go beyond the community of nuclear physics and opens avenues for investigating the early universe and provides a deeper understanding of the strong interaction dynamics under extreme conditions.