Analysis of Beauty Quark Hadronization in Vacuum and Quark-Gluon Plasma with CMS

Abstract

An analysis of fully reconstructed 𝐵ₛ⁰ and 𝐵⁺ mesons decay into 𝐽/𝜓 and strange hadrons using Compact Muon Solenoid (CMS) Experiment 2017 𝑝𝑝 dataset and 2018 PbPb data at the center of mass energy per nucleon √𝑠𝑁𝑁 = 5.02 TeV at the Large Hadron Collider (LHC) is presented. We apply machine learning techniques along with multivariate analysis to obtain significant B-meson signals and extend the kinematic regime of B-meson measurements with higher precision. In our analysis, 𝐵0𝑠 signal of greater than 5 𝜎 significance is observed for the first time in heavy-ion collisions. The measured 𝐵ₛ⁰/𝐵⁺ ratios as functions of transverse momentum and event centrality in PbPb collisions along with 𝑝𝑝 references are compared with theoretical model predictions. These results will help elucidate the beauty quark hadronization mechanisms in vacuum and quark-gluon plasma at the LHC energy. Significant B-meson signals have also been observed at low very 𝑝ₜ and high event multiplicity in 𝑝𝑝 collisions, which will allow us to study beauty quark hadrochemistry in small systems as well as energy loss mechanisms in the future.