2017/09/30 by Lorenzo Calibbi, Andreas Crivellin, Tianjun Li · 2 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-ph
paper · pdf · doi:10.1103/physrevd.98.115002
published as Phys. Rev. D 98, 115002 (2018) · 8 pages, 2 figures, 2 tables, version accepted for publication in PRD
openalex created_date 2017/09/15 · openalex publication_date 2018/12/04 · arxiv created 2018/12/07 · arxiv updated 2018/12/12 · openalex updated_date 2026/08/06
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 KL\ensuremath→\ensuremathμe and K\ensuremath→\ensuremathπ\ensuremathμe 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 Bs\ensuremath→\ensuremathτ+\ensuremathτ^\ensuremath-. Furthermore, also in b\ensuremath→s\ensuremathℓ+\ensuremathℓ^\ensuremath- 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\ensuremath→s\ensuremathτ\ensuremathμ. 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.