A near-minimal leptoquark model for reconciling flavour anomalies and generating radiative neutrino masses

• Published in: The journal of high energy physics 2019-10, Vol.2019 (10), p.1-49, Article 106
• Main Authors: Bigaran, Innes, Gargalionis, John, Volkas, Raymond R.
• Format: Article
• Language: English
• Subjects: Anomalies; Beyond Standard Model; Classical and Quantum Gravitation; Comet nuclei; Elementary Particles; Flavor (particle physics); High energy physics; Leptons; Neutrino Physics; Neutrinos; Particle decay; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; Standard model (particle physics); String Theory
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP10(2019)106

A bstract We introduce two scalar leptoquarks, the SU(2) L isosinglet denoted ϕ ∼ ( 3 , 1 , − 1 / 3) and the isotriplet φ ∼ ( 3 , 3 , − 1 / 3), to explain observed deviations from the standard model in semi-leptonic B -meson decays. We explore the regions of parameter space in which this model accommodates the persistent tensions in the decay observables R D ( ∗ ), R K ( ∗ ) , and angular observables in b → sμμ transitions. Additionally, we exploit the role of these exotics in existing models for one-loop neutrino mass generation derived from ∆ L = 2 effective operators. Introducing the vector-like quark χ ∼ ( 3 , 2 , − 5 / 6) necessary for lepton-number violation, we consider the contribution of both leptoquarks to the generation of radiative neutrino mass. We find that constraints permit simultaneously accommodating the flavour anomalies while also explaining the relative smallness of neutrino mass without the need for cancellation between leptoquark contributions. A characteristic prediction of our model is a rate of muon-electron conversion in nuclei fixed by the anoma- lies in b → sμμ and neutrino mass; the COMET and Mu2e experiments will thus test and potentially falsify our scenario. The model also predicts signatures that will be tested at the LHC and Belle II.