The $B_c^{+}$ meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the $B_c^{+}$ meson in lead-lead (Pb-Pb) and proton-proton ($pp$) collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{NN}}=5.02\mathrm{TeV}$, via the $B_c^{+}\to (J/\psi \to {\mu }^{+}{\mu }^{-}){\mu }^{+}{\nu }_{\mu }$ decay. The $B_c^{+}$ nuclear modification factor, derived from the Pb-Pb–to–$pp$ ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the Pb-Pb 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.

中文翻译：

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观察 Pb-Pb 和 pp 碰撞中的 Bc+介子 atsNN=5.02TeV 并测量其核修饰因子

这${乙}_C^{+}$在重离子碰撞中首次观察到介子。来自 CMS 检测器的数据用于研究${乙}_C^{+}$铅铅 (Pb-Pb) 和质子-质子 ($pp$) 每个核子对的质心能量碰撞$\sqrt{s_{ññ}}=5.02\mathrm{TeV}$，通过${乙}_C^{+}\to (Ĵ/\psi \to {\mu }^{+}{\mu }^{-}){\mu }^{+}{\nu }_{\mu }$衰变。这${乙}_C^{+}$核修饰因子，源自 Pb-Pb–to–$pp$生产横截面的比率，在 trimuon 横向动量和 Pb-Pb 碰撞中心性的两个箱中测量。这${乙}_C^{+}$与夸克尼亚和大多数开放的重味介子相比，介子受到的抑制更少，这表明在重离子碰撞中产生的高温和致密核物质的影响有助于其产生。该测量为夸克-胶子等离子体中重味介子产生过程中抑制和增强机制的相互作用提供了一个有希望的新探索。