fcme in Au+Au 200 GeV after background estimate

Updated on Fri, 2025-05-02 10:21. Originally created by fengyich on 2024-08-17 20:50.

Title: Measurement of Charge-Dependent Azimuthal Correlations and Possible Evidence of the Chiral Magnetic Effect in Au+Au Collisions at √s_NN=200 GeV

PAs: Yicheng Feng, Haojie Xu, Jie Zhao, Fuqiang Wang

Targeted journal: PRL

Abstract:

Vacuum fluctuations of the topological gluon field will produce a chirality imbalance of quarks because of quark-gluon interactions in quantum chromodynamics. Such a chirality imbalance will result in an electric current along an external magnetic field, a phenomenon called the chiral magnetic effect (CME). We measure reaction plane- and charge-dependent azimuthal correlations, sensitive to the CME-induced charge separation, in Au+Au collisions at nucleon-nucleon center-of-mass energy of √s_NN=200 GeV at BNL's Relativistic Heavy Ion Collider. The elliptic flow-induced background and contamination by genuine particle correlations are removed. We report possible evidence of a CME signal fraction of (25±7±2)%, with a significance of 3.4 standard deviations.

Conclusion:
After eliminating flow-induced backgrounds and nonflow contamination, we report a possible evidence of CME signal in 20--50\% centrality Au+Au collisions at √s_NN=200 GeV with a signal fraction of f_CME=(25±7±2)% in the measured inclusive Δγ, a 3.4 standard deviation away from, or a 3.4×10^-4 probability to be a fluctuation of, a null signal.

Status:
After PWGC preview

Paper draft:
drupal.star.bnl.gov/STAR/system/files/AuAuFcme_Paper_Pwg_v4.pdf

Analysis note:
drupal.star.bnl.gov/STAR/system/files/AuAuFcme_Note_Pwg_v4.pdf

CVS: