Unified explanation of flavor anomalies, radiative neutrino mass 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 $V_{\mathrm{LQ}}(3,1,2/3)$ and a scalar diquark $S_{\mathrm{DQ}}(6,1,4/3)$ under the SM gauge group $SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y$, in order to simultaneously explain the $b\to s{\ell }^{+}{\ell }^{-}$ (with $\ell =e,\mu$) and $b\to c{l}^{-}{\bar{\nu }}_l$ (with $l=e,\mu ,\tau$) 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 $b\to s{\ell }^{+}{\ell }^{-}$ and $b\to c{l}^{-}{\bar{\nu }}_l$ 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 $\tau$ decay modes, such as $B_s\to l_i^{+}{l}_j^{-},B\to K^{(\ast )}{l}_i^{+}{l}_j^{-},B_s\to \varphi l_i^{+}{l}_j^{-}$, ${\rm Y}(nS)\to \mu \tau$ and $\tau \to \mu \gamma$, $\tau \to \mu \varphi ({\eta }^{(\prime )})$, respectively. Minimally extending this model by adding a fermion singlet $\chi (1,1,0)$ 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.

Comments: 51 pages, 13 figures, 7 tables; version to appear in Phys. Rev. D