A measurement of the ratio of branching fractions 𝑅⁢(𝐽/𝜓) =ℬ⁡(𝐵+𝑐 →𝐽/𝜓⁢𝜏+⁢𝜈𝜏)/ℬ⁡(𝐵+𝑐 →𝐽/𝜓⁢𝜇+⁢𝜈𝜇) in the 𝐽/𝜓 →𝜇+⁢𝜇−, 𝜏+→𝜇+⁢𝜈𝜇⁢¯𝜈𝜏 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/𝜓) = 0.1⁢7+0.18−0.17⁢(stat)+0.21−0.22⁢(syst)+0.19−0.18⁢(theo) = 0.17 ±0.33, agrees with the value of 0.2582 ±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+𝑐 mesons, which are currently only produced at the LHC.

Test of lepton flavor universality in semileptonic Bc+ meson decays in proton-proton collisions at sqrt(s) = 13 TeV

Cavallo, N.;Fabozzi, F.;
2025-01-01

Abstract

A measurement of the ratio of branching fractions 𝑅⁢(𝐽/𝜓) =ℬ⁡(𝐵+𝑐 →𝐽/𝜓⁢𝜏+⁢𝜈𝜏)/ℬ⁡(𝐵+𝑐 →𝐽/𝜓⁢𝜇+⁢𝜈𝜇) in the 𝐽/𝜓 →𝜇+⁢𝜇−, 𝜏+→𝜇+⁢𝜈𝜇⁢¯𝜈𝜏 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/𝜓) = 0.1⁢7+0.18−0.17⁢(stat)+0.21−0.22⁢(syst)+0.19−0.18⁢(theo) = 0.17 ±0.33, agrees with the value of 0.2582 ±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+𝑐 mesons, which are currently only produced at the LHC.
2025
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11563/201943
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