Bottom quark energy loss and hadronization with B⁺ and B⁰ₛ nuclear modification factors using pp and PbPb collisions at √sNN = 5.02 TeV

Abstract

The production cross sections of B⁰ₛ 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 B⁰ₛ → J/ψ(μ⁺μ⁻)ϕ(1020)(K⁺K⁻) and B⁺ → J/ψ(μ⁺μ⁻)K⁺ decay channels. Results are presented in the transverse momentum (pT) range 7–50 GeV/c and the rapidity interval |y| < 2.4 for the B mesons. The measured pT-differential cross sections of B⁺ and B⁰ₛ 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, RAA, of the B mesons are determined. For pT > 10 GeV/c, both mesons are found to be suppressed in PbPb collisions (with RAA values significantly below unity), with less suppression observed for the B⁰ₛ mesons. In this pT range, the RAA values for the B⁺ mesons are consistent with those for inclusive charged hadrons and D0 mesons. Below 10 GeV/c, both B⁺ and B⁰ₛ are found to be less suppressed than either inclusive charged hadrons or D0 mesons, with the RAA value consistent with unity. The RAA values found for the B⁺ and B⁰ₛ 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.