Bottom quark energy loss and hadronization with B+ and B s 0 nuclear modification factors using pp and PbPb collisions at s NN = 5.02 TeV

Abstract

The production cross sections of B s 0 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 s 0 → 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 B s 0 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 B s 0 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 B s 0 are found to be less suppressed than either inclusive charged hadrons or D0 mesons, with the B s 0 RAA value consistent with unity. The RAA values found for the B+ and B s 0 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.