Probing the R-parity violating supersymmetric effects in the exclusive   b\to c\ell^-\bar{\nu}_\ell decays
  Motivated by recent results from the LHCb, BABAR and Belle collaborations on B\to D^{(*)}\ell^-\bar{\nu}_\ell decays, which significantly deviate from the Standard Model and hint the possible new physics beyond the Standard Model, we probe the R-parity violating supersymmetric effects in B^-_c\to \ell^-\bar{\nu}_\ell and B\to D^{(*)}\ell^-\bar{\nu}_\ell decays. We find that (i) \mathcal{B}(B^-_c\to e^- \bar{\nu}_e) and \mathcal{B}(B^-_c\to\mu^-\bar{\nu}_\mu) are sensitive to the constrained slepton exchange couplings; (ii) the normalized forward-backward asymmetries of B\to De^-\bar{\nu}_{e} decays have been greatly affected by the constrained slepton exchange couplings, and their signs could be changed; (iii) all relevant observables in the exclusive b\to c\tau^-\bar{\nu}_\tau decays and the ratios \mathcal{R}(D^{(*)}) are sensitive to the slepton exchange coupling, \mathcal{R}(D^*) could be enhanced by the constrained slepton exchange coupling to reach each 95\% confidence level experimental range from BABAR, Belle and LHCb, but it could not reach the lower limit of the 95\% confidence level experimental average. Our results in this work could be used to probe R-parity violating effects, and will correlate with searches for direct supersymmetric signals at the running LHCb and the forthcoming Belle-II. 
Jie Zhu, Hua-Min Gan, Ru-Min Wang, Ying-Ying Fan, Qin Chang, Yuan-Guo   Xu
hep-ph