Unified explanation of flavor anomalies, radiative neutrino masses, and ANITA anomalous events in a vector leptoquark model

Abstract

Driven by the recent experimental hints of lepton-flavor-universality violation in the bottom-quark sector, we consider a simple extension of the Standard Model (SM) with an additional vector leptoquark ${V}_{\mathrm{LQ}}(\mathbf{3},\mathbf{1},2/3)$ and a scalar diquark ${S}_{\mathrm{DQ}}(\mathbf{6},\mathbf{1},4/3)$ under the SM gauge group $SU(3{)}_{c}\ifmmode\times\else\texttimes\fi{}SU(2{)}_{L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{Y}$, in order to simultaneously explain the $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ (with $\ensuremath{\ell}=e$, $\ensuremath{\mu}$) and $b\ensuremath{\rightarrow}c{l}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{l}$ (with $l=e$, $\ensuremath{\mu}$, $\ensuremath{\tau}$) flavor anomalies, as well as to generate small neutrino masses through a two-loop radiative mechanism. We perform a global fit to all the relevant and up-to-date $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ and $b\ensuremath{\rightarrow}c{l}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{l}$ data under the assumption that the leptoquark couples predominantly to second and third-generation SM fermions. We then look over the implications of the allowed parameter space on lepton-flavor-violating $B$ and $\ensuremath{\tau}$ decay modes, such as ${B}_{s}\ensuremath{\rightarrow}{l}_{i}^{+}{l}_{j}^{\ensuremath{-}}$, $B\ensuremath{\rightarrow}{K}^{(*)}{l}_{i}^{+}{l}_{j}^{\ensuremath{-}}$, ${B}_{s}\ensuremath{\rightarrow}\ensuremath{\phi}{l}_{i}^{+}{l}_{j}^{\ensuremath{-}}$, $\mathrm{\ensuremath{\Upsilon}}(nS)\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\tau}$, and $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$, $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\phi}({\ensuremath{\eta}}^{(\ensuremath{'})})$, respectively. Minimally extending this model by adding a fermion singlet $\ensuremath{\chi}(\mathbf{1},\mathbf{1},0)$ also explains the ANITA anomalous upgoing events. Furthermore, we provide complementary constraints on leptoquark and diquark couplings from high-energy collider and other low-energy experiments to test this model.

Topics & Concepts