Lepton Flavour Universality tests in $b\to cl\nu$ decays at LHCb

Abstract

The Standard Model predicts that the electroweak couplings to the three charged leptons are identical. However, in the last decade, experimental measurements have suggested that semileptonic processes involving taus could have a slightly enhanced decay rate compared to their muonic counterparts. If confirmed, this would be an unambiguous sign of New Physics, with various scenarios introducing additional interactions that couple preferentially to the third generation. Two recent lepton universality tests performed at LHCb are presented in this proceedings of the first edition of the New Frontiers in Lepton Flavour workshop.

arXiv commentSubmitted as part of the proceedings of the New Frontiers in Lepton Flavour workshop

References in corpus (5)

• Measurement of the ratio of branching fractions $\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\mu }^{-}{\overline{\nu }}_{\mu })$
• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2021
• Measurement of the ratio of the $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ and $B^0\to D^{\ast -}{\mu }^{+}{\nu }_{\mu }$ branching fractions using three-prong $\tau$-lepton decays
• Test of lepton flavour universality using $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ decays with hadronic $\tau$ channels
• Model-independent method for measuring the angular coefficients of $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ decays