Leptoquarks facing flavour tests and $b\to s\ell \ell$ after Moriond 2021

Abstract

In view of the emerging hints for the violation of lepton flavour universality in several $B$-meson decays, we conduct a model-independent study (effective field theory approach) of several well-motivated new physics scenarios. Taking into account the most recent LHCb data, we provide updates to Wilson coefficient fits for numerous popular new physics hypotheses. We also consider a promising model of vector leptoquarks, which in addition to explaining the $B$-meson decay anomalies ($R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$) would have an extensive impact for numerous flavour observables. We identify promising decay modes allowing to (indirectly) probe such an extension: these include positive signals (at Belle II or LHCb) for $\tau \to \varphi \mu$, $B_{(s)}$-meson decays to ${\tau }^{+}{\tau }^{-}$ and ${\tau }^{+}{\mu }^{-}$ (${\tau }^{+}{e}^{-}$) final states, as well as an observation of certain charged lepton flavour violation transitions at COMET and Mu2e. We also argue how the evolution of the experimental determination of $R_{D^{(\ast )}}$ can prove instrumental in falsifying a vector leptoquark explanation of the anomalous $B$-meson decay data.

6+2 pages, 6+6 Figures, contribution to the "2021 Electroweak session of the 55th Rencontres de Moriond", the appendix contains numerous updates on global fits due to the updated 2021 measurement of $R_K$

References in corpus (1)

• Measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^{\ast })$ with a semileptonic tagging method

Cited by in corpus (8)

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• Leptoquark Option for $B$-meson Anomalies and Leptonic Signatures
• Explanations for anomalies of muon anomalous magnetic dipole moment, $b\to s\mu \bar{\mu }$ and radiative neutrino masses in a leptoquark model
• Studying the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies and $(g-2{)}_{\mu }$ in $R$-parity violating MSSM framework with the inverse seesaw mechanism
• Explaining anomalies of $B$-physics, muon $g-2$ and $W$ mass in $R$-parity violating MSSM with seesaw mechanism
• Discriminating 1D new physics solutions in $b\to s\ell \ell$ decays