Measurement of global spin alignment of vector mesons at RHIC

2022/11/22 by Subhash Singha, Singha, Subhash
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High-Energy Particle Collisions Research #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th) #Physics of Superconductivity and Magnetism #Quantum Chromodynamics and Particle Interactions

paper · pdf · doi:10.48550/arxiv.2211.12013

openalex publication_date 2022/11/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We report the measurements of spin alignment (ρ₀₀) for K^*0, K^*0, K^*+, and K^*- vector mesons in RHIC isobar collisions (Zr+Zr and Ru+Ru) at √s_\mathrm NN = 200 GeV. We observe the first non-zero spin alignment for K^*± in heavy-ion collisions. The K^*± ρ₀₀ is about 3.9σ larger than that of K^*0. The observed difference and the ordering between K^*± and K^*0 are surprising, and require further inputs from theory. When comparing between the isobar and Au+Au collisions, no significant system size dependence in K^*0 ρ₀₀ is observed within uncertainties.

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