Pair invariant mass to isolate background in the search for the chiral magnetic effect in Au + Au collisions at √s.sub.NN./sub.=200 GeV

0565003 - ÚJF 2023 RIV US eng J - Journal Article
Abdallah, M. S. - Adam, J. - Adamczyk, L. - Adams, J. R. - Bielčík, J. - Bielčíková, Jana - Federič, Pavol - Holub, L. - Chaloupka, P. - Kosarzewski, L. K. - Kramárik, L. - Líčeník, Robert - Ponimatkin, Georgij - Prozorova, V. - Robotková, Monika - Rusňák, Jan - Šimko, Miroslav - Šumbera, Michal - Truhlář, T. - Trzeciak, B. A. - Vaněk, Jan … Total 391 authors
Pair invariant mass to isolate background in the search for the chiral magnetic effect in Au + Au collisions at √s_NN=200 GeV.
Physical Review C. Roč. 106, č. 3 (2022), č. článku 034908. ISSN 2469-9985. E-ISSN 2469-9993
R&D Projects: GA MŠMT LTT18002
Research Infrastructure: BNL-CZ II - 90109
Institutional support: RVO:61389005
Keywords : STAR experiment * heavy ion collisions
OECD category: Particles and field physics
Impact factor: 3.1, year: 2022
Method of publishing: Limited access
https://doi.org/10.1103/PhysRevC.106.034908

Quark interactions with topological gluon configurations can induce local chirality imbalance and parity violation in quantum chromodynamics, which can lead to the chiral magnetic effect (CME)-an electric charge separation along the strong magnetic field in relativistic heavy-ion collisions. The CME-sensitive azimuthal correlator observable (Delta gamma) is contaminated by background arising, in part, from resonance decays coupled with elliptic anisotropy (v(2)). We report here differential measurements of the correlator as a function of the pair invariant mass (m(inv)) in 20-50% centrality Au + Au collisions at root s(NN) = 200 GeV by the STAR experiment at the BNL Relativistic Heavy Ion Collider. Strong resonance background contributions to Delta gamma. are observed. At large m(inv) where this background is significantly reduced, the Delta gamma. value is found to be significantly smaller. An event-shape-engineering technique is deployed to determine the v(2) background shape as a function of m(inv). We extract a v(2)-independent and m(inv)-averaged signal Delta gamma(sig) = (0.03 +/- 0.06 +/- 0.08) x 10(-4), or (2 +/- 4 +/- 5)% of the inclusive Delta gamma (m(inv) > 0.4 GeV/c(2)) = (1.58 +/- 0.02 +/- 0.02) x 10(-4), within pion p(T) = 0.2-0.8 GeV/c and averaged over pseudorapidity ranges of -1 < eta < -0.05 and 0.05 < eta < 1. This represents an upper limit of 0.23 x 10(-4), or 15% of the inclusive result, at 95% confidence level for the m(inv)-integrated CME contribution.
Permanent Link: https://hdl.handle.net/11104/0336570