Status of CME Search Before Isobar Collisions and Methods of Blind Analysis From STAR

TL;DR

This paper reviews the status of CME searches using STAR data before isobar collisions, discusses background challenges, new analysis methods, and outlines the blind analysis procedure, also considering future energy scans with upgraded detectors.

Contribution

It introduces new analysis methods and observables for isolating CME signals and describes the blind analysis procedure for isobar data at STAR.

Findings

Recent STAR analyses employ new methods to distinguish CME signals from backgrounds.

Blind analysis of isobar data aims to provide a decisive test of CME.

Upgrades like the event-plane detector enhance CME search capabilities at lower energies.

Abstract

The STAR collaboration is currently pursuing the blind analysis of the data for isobar collisions that was performed at RHIC in the year 2018 to make a decisive test of the Chiral Magnetic Effect (CME). Why is it so difficult to detect signals of CME in the experiment? Do we really understand different sources of background? Why observing similar charge separation between p/d+A and A+A does not stop us from pursuing the search for CME? In this contribution, I attempt to address some of these questions and briefly outline a few recent STAR analyses based on new methods and observables to isolate the possible CME-driven signal and non-CME background contributions at the top RHIC energy. Finally, I describe the procedure for the blind analysis of the isobar data. An outstanding question remains -- what happens if we go down in energy? I address this by discussing how the new event-plane detector (EPD) upgrade provides a new capability at STAR towards CME search using the data from the RHIC BES-II program.