| 摘要: |
Lepton number as a fourth color is an intriguing theoretical idea which is combined with a possible left-right symmetry within the famous Pati-Salam (PS) model. In the conventional PS model, a spontaneous breaking of the PS gauge group down to the SM, one can only take place at very high scales (above the PeV scale) due to the stringent bounds from K-L -> mu e and K -> pi mu e induced by the resulting vector leptoquarks. In this paper, we show that these constraints can be avoided once additional vectorlike fermions are introduced and, thus, a breaking at the TeV scale is possible. We consider the flavor phenomenology of this model in the context of the intriguing hints for new physics in semileptonic B decays. The necessary violation of lepton flavor universality is induced by mixing SM and vectorlike fermions. Concerning R(D) and R(D*), we find that sizable effects are possible while respecting the bounds from other flavor observables but predicting a large enhancement of B-s -> tau(+)tau(-) . Furthermore, also in b -> sl(+)l(-) transitions, the observed deviations from the SM predictions [including R(K) and R(K*)] can be explained with natural values for the free parameters of the model without any fine-tuning, predicting sizable decay rates for b -> s tau mu. Finally, the anomaly in the anomalous magnetic moment of the muon can be accounted for by a loop contribution involving the vector leptoquark and vectorlike leptons. |
