Search for new physics in semileptonic B-decays

Abstract

Semileptonic decays provide an excellent environment for testing the Standard Model (SM). Violation of lepton universality would be a smoking gun for physics beyond the SM. Using semi-tauonic $B$ decays, LHCb finds a value of $\mathcal{R}(D^{\ast })=\mathcal{B}({\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau })/\mathcal{B}({\bar{B}}^0\to D^{\ast +}{\mu }^{-}{\bar{\nu }}_{\mu })=0.336\pm 0.027(\mathrm{stat})\pm 0.030(\mathrm{syst})$, which is 2.1 standard deviations larger than the value expected from the SM. Moreover, the measurement of the $CP$ asymmetry in mixing of $B_s^0$ mesons is highly sensitive to physics beyond the SM. This article presents the latest result on semileptonic asymmetries; using the full Run 1 dataset, it is found that $a_{\mathrm{sl}}^s=(0.39\pm 0.26(\mathrm{stat})\pm 0.20(\mathrm{syst}))\%$, which is consistent with the Standard Model.

6 pages, 8 figures, Contribution to the Proceedings of the 38th International Conference on High Energy Physics, ICHEP 2016, Chicago, IL, USA

References in corpus (3)

• Measurement of the branching ratio of ${\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with a semileptonic tagging method
• Measurement of the semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$ mixing
• Study of CP asymmetry in B0-B0bar mixing with inclusive dilepton events