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Observation of the B$_\mathrm{c}^+$ meson in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

The collaboration
CMS-HIN-20-004, 2022.

Abstract
The B$_\mathrm{c}^+$ meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to measure the production of the B$_\mathrm{c}^+$ meson in lead-lead (PbPb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, via the B$_\mathrm{c}^+$$\to (J/\psi$$\to$$\mu^+\mu^-$)$\mu^+\nu_\mu$ decay. The B$_\mathrm{c}^+$ 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$_\mathrm{c}^+$ meson is shown to be less suppressed than other 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 first observation of the B$_\mathrm{c}^+$ meson in heavy ion collisions sets forth a new promising probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.

• #### Bc cross sections

Data from Figure 3

10.17182/hepdata.111309.v1/t1

The $B_c$ meson production (pp-equivalent) cross-section times branching fraction of the $B_c\rightarrow (J/\psi \rightarrow \mu\mu) \mu \nu_{\mu}$ decay in pp...

• #### Bc RAA vs pT

Data from Figure 4 left

10.17182/hepdata.111309.v1/t2

The $B_c$ meson nuclear modification factor in PbPb collisions, in $p_T^{\mu\mu\mu}$ bins corresponding to different trimuon rapidity ranges. The total...

• #### Bc RAA vs centrality

Data from Figure 4 right

10.17182/hepdata.111309.v1/t3

The $B_c$ meson nuclear modification factor in PbPb collisions, in centrality bins, integrated over the studied kinematic range. The cut...