Bottom quark energy loss and hadronization with B$^+$ and B$^0_\mathrm{s}$ nuclear modification factors using pp and PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

TL;DR

This paper measures B meson production in pp and PbPb collisions at 5.02 TeV, analyzing their suppression patterns to understand bottom quark energy loss and hadronization in quark-gluon plasma.

Contribution

It provides the first detailed measurements of B$^0_s$ and B$^+$ nuclear modification factors at this energy, offering new insights into bottom quark interactions in heavy ion collisions.

Findings

B$^+$ and B$^0_s$ cross sections agree with pQCD calculations.

Both mesons are suppressed in PbPb collisions below 10 GeV/c.

Less suppression observed for B$^0_s$ compared to B$^+$.

Abstract

The production cross sections of B$^0_\mathrm{s}$ and B$^+$ mesons are reported in proton-proton (pp) collisions recorded by the CMS experiment at the CERN LHC with a center-of-mass energy of 5.02 TeV. The data sample corresponds to an integrated luminosity of 302 pb$^{-1}$. The cross sections are based on measurements of the B$^0_\mathrm{s}$ $\to$ J/$\psi (\mu^+\mu^-)\phi$(1020) (K$^+$K$^-$) and B$^+$ $\to$ J/$\psi (\mu^+\mu^-)$K$^+$ decay channels. Results are presented in the transverse momentum ($p_\mathrm{T}$) range 7-50 GeV/$c$ and the rapidity interval $\lvert y \rvert$ $\lt$ 2.4 for the B mesons. The measured $p_\mathrm{T}$-differential cross sections of B$^+$ and B$^0_\mathrm{s}$ in pp collisions are well described by fixed-order plus next-to-leading logarithm perturbative quantum chromodynamics calculations. Using previous PbPb collision measurements at the same nucleon-nucleon center-of-mass energy, the nuclear modification factors, $R_\mathrm{AA}$, of the B mesons are determined. For $p_\mathrm{T}$ $\lt$ 10 GeV/$c$, both mesons are found to be suppressed in PbPb collisions (with $R_\mathrm{AA}$ values significantly below unity), with less suppression observed for the B$^0_\mathrm{s}$ mesons. In this $p_\mathrm{T}$ range, the $R_\mathrm{AA}$ values for the B$^+$ mesons are consistent with those for inclusive charged hadrons and D$^0$ mesons. Below 10 GeV/$c$, both B$^+$ and B$^0_\mathrm{s}$ are found to be less suppressed than either inclusive charged hadrons or D$^0$ mesons, with the B$^0_\mathrm{s}$ $R_\mathrm{AA}$ value consistent with unity. The $R_\mathrm{AA}$ values found for the B$^+$ and B$^0_\mathrm{s}$ are compared to theoretical calculations, providing constraints on the mechanism of bottom quark energy loss and hadronization in the quark-gluon plasma, the hot and dense matter created in ultrarelativistic heavy ion collisions.