Abstract
The B⁺꜀ meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the B⁺꜀ meson in lead-lead (PbPb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of √sNN= 5.02 TeV, via the B⁺꜀ → (J/ψ → μ+μ−)μ+νμ decay. The B⁺꜀ nuclear modification factor, derived from the PbPb-to-pp ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the PbPb collision centrality. The B+c meson is shown to be less suppressed than quarkonia and most of the open heavy-flavor mesons, suggesting that effects of the hot and dense nuclear matter created in heavy ion collisions contribute to its production. This measurement sets forth a promising new probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.