Suppression of open bottom at high pT via non-prompt J/ψ decays in PbPb collisions at 2.76 TeV with CMS

Abstract

Abstract Measurements of the nuclear modification factor of mesons with open heavy flavor content in PbPb collisions at s N N = 2.76 TeV from the CMS experiment will be presented. These modification factors provide stringent constraints on the theoretical models of heavy quark energy loss. Until recently only indirect measurements of this effect existed, through single electrons from semileptonic open heavy-flavor decays. The importance of an unambiguous measurement of open bottom flavor is driven by the lack of knowledge regarding key features of the dynamics of parton energy loss in the QGP, such as its color-charge and parton-mass dependencies and the relative role of radiative and collisional energy loss. CMS measures the nuclear modification factor of b hadrons, identified via their decays into J / ψ displaced from the primary collision vertex. First results have shown that b hadrons are strongly suppressed in PbPb collisions at a level comparable to open charm. New results on the centrality dependence of non-prompt J / ψ R A A are presented, based on the full 2011 PbPb data sample corresponding to an integrated luminosity of 150 μ b − 1 .