B ¯ → D ∗ τ ν ¯ $$ \overline{B}\to {D}^{\left(\ast \right)}\tau \overline{\nu} $$ excesses in ALRSM constrained from B, D decays and D 0 − D ¯ 0 $$ {D}^0-{\overline{D}}^0 $$ mixing

Abstract

Recent experimental results from the LHCb, BaBar and Belle collaborations on the semitauonic decays of B meson,B → D ( * ) τν, showing a significant deviation from the Standard Model (SM), hint towards a new physics scenario beyond the SM. In this work, we show that these enhanced decay rates can be explained within the framework of E 6 motivated Alternative Left-Right Symmetric Model (ALRSM), which has been successful in explaining the recent CMS excesses and has the feature of accommodating high scale leptogenesis. The R-parity conserving couplings in ALRSM can contribute universally to bothB → Dτν andB → D * τν via the exchange of scalar leptoquarks. We study the leptonic decays D + s → τ +ν , B + → τ +ν , D + → τ +ν and D 0 −D 0 mixing to constrain the couplings involved in explaining the enhanced B decay rates and we find that ALRSM can explain the current experimental data on R(D ( * ) ) quite well while satisfying these constraints.

Electroweak couplings and LHC constraints on alternative Z′ models in E6

“…Finally it is important to stress that the recent LHCb anomalies could also be explained by E 6 subgroups. [54][55][56][57][58][59] A natural continuation of our work would be to find which of these models are able to explain the anomalies. That is an interesting question since the E 6 models, in general, have been considered as phenomenologically safe.…”

Remarks on the Standard Model predictions for R(D) and R(D*Kim1, López-Castro2, Tostado3 et al. 2017Phys. Rev. D220222View full textAdd to dashboardCite

“…These hints of a possible violation of lepton universality have prompted many theoretical proposals, which include the exchange of charged scalars [12][13][14][15][16][17][18][19], leptoquarks (or, equivalently, R-parity violating supersymmetry) [16,18,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37], vector resonances [38] or a W boson [18,36,[39][40][41][42].…”

Phenomenology of an SU(2) × SU(2) × U(1) model with lepton-flavour non-universality

“…A considerable amount of efforts and model building activities have been devoted to these B-decay anomalies, though mainly focused on models that can accommodate only one of the anomalies: either R(D ( * ) ) or B → K ( * ) + − . The R(D ( * ) ) anomalies have been explained with charged scalars [24][25][26][27][28][29][30][31], leptoquarks (or, equivalently, R-parity violating supersymmetry) [32][33][34][35][36][37][38][39], or a W boson [40]. Effects due to the presence of light sterile neutrinos have also been explored in Refs.…”