First measurement of the Bc+ meson nuclear modification factor in PbPb collisions with CMS

Abstract

The Bc+ meson is observed in lead-lead and proton-proton collisions at a center-of-mass energy per nucleon pair of √SNN = 5.02 TeV, via the Bc+ → (J/ψ → μ+μ−)μ+vμ decay and using 2017 and 2018 data from the CMS detector. The resulting Bc+ nuclear modification factor is measured in two bins of the trimuon transverse momentum and of the collision centrality. Less suppression is observed than for other quarkonia and most open heavy flavour mesons. This first observation of the Bc+ meson in heavy ion collisions will shed light on the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.