Hati, ChandanChandanHatiKumar, GirishGirishKumarMahajan, NamitNamitMahajan2025-08-222025-08-222015-11-012331-8422arXiv:1511.03290https://d8.irins.org/handle/IITG2025/18159Recent 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.en-USTV- excessesALRSMSemitauonic decayse-Printe-Print123456789/615