Test of lepton flavor universality in semileptonic B${}_{\text{c}}^{+}$ meson decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV

Abstract

A measurement of the ratio of branching fractions $R$(J/$\psi$) = $\mathcal{B}$(B${}_{\text{c}}^{+}$ $\to$ J/$\psi$${\tau }^{+}{\nu }_{\tau }$) / $\mathcal{B}$(B${}_{\text{c}}^{+}$ $\to$ J/$\psi$${\mu }^{+}{\nu }_{\mu }$) in the J/$\psi$ $\to$ ${\mu }^{+}{\mu }^{-}$, ${\tau }^{+}$ $\to$ ${\mu }^{+}{\mu }_{\tau }{\overline{\nu }}_{\tau }$ decay channel is presented. This measurement uses a sample of proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment in 2018, corresponding to an integrated luminosity of 59.7 fb${}^{-1}$. The measured ratio, $R$(J/$\psi$) = 0.17 ${}_{-0.17}^{+0.18}$ (stat) ${}_{-0.22}^{+0.21}$ (syst) ${}_{-0.18}^{+0.19}$ (theo) = 0.17 $\pm$ 0.33, agrees with the value of 0.2582 $\pm$ 0.0038 predicted by the standard model, which assumes lepton flavor universality. By testing lepton flavor universality, this measurement is a probe of new physics using B${}_{\text{c}}^{+}$ mesons, which are currently only produced at the LHC.

arXiv commentReplaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/BPH-22-012 (CMS Public Pages)

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Cited by in corpus (1)

• Measurement of the ratio of the B${}_{\mathrm{c}}^{+}$ $\to$ J/$\psi$${\tau }^{+}{\nu }_{\tau }$ and B${}_{\mathrm{c}}^{+}$ $\to$ J/$\psi$ ${\mu }^{+}{\nu }_{\mu }$ branching fractions using three-prong $\tau$ lepton decays