$\bar{B}\rightarrow D^{(\ast)}\tau \bar{\nu}$ excesses in ALRSM constrained from $B$, $D$ decays and $D^{0}-\bar{D}^{0}$ mixing

TL;DR

This paper demonstrates that the observed excesses in semitauonic B meson decays can be explained by an E6 motivated ALRSM, which also aligns with constraints from other meson decays and mixing phenomena.

Contribution

The study shows that ALRSM with scalar leptoquarks can account for B decay anomalies while satisfying various experimental constraints.

Findings

ALRSM explains B decay excesses effectively.

Constraints from D and D0-D0bar mixing are satisfied.

Model aligns with recent experimental data.

Abstract

Recent experimental results from the LHCb, BaBar and Belle collaborations on the semitauonic decays of $B$ meson, $\bar{B}\rightarrow D^{(\ast)}\tau \bar{\nu}$, 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 both $\bar{B}\rightarrow D \tau \bar{\nu}$ and $\bar{B}\rightarrow D^{(\ast)}\tau \bar{\nu}$ via the exchange of scalar leptoquarks. We study the leptonic decays $D_{s}^{+} \rightarrow \tau^{+} \bar{\nu}$, $B^{+}\rightarrow \tau^{+} \bar{\nu}$, $D^{+}\rightarrow \tau^{+} \bar{\nu}$ and $D^{0}$-$\bar{D}^{0}$ 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 $\mathcal{R}(D^{(\ast)})$ quite well while satisfying these constraints.