Exploring $R_D$, $R_{D^{\ast}}$ and $R_{J/\Psi}$ anomalies

Abstract

Deviations from the standard model predictions have been reported in various observables concerned with the lepton flavor universality. At present, the deviation of the measured values of $R_D$ and $R_{D^{\ast}}$ from the standard model expectation is exceeded by $2.3\sigma$ and $3.4\sigma$, respectively. Very recently LHCb has measured the ratio of branching ratio $R_{J/\Psi} = \mathcal B(B_c \to J/\Psi\tau\nu)/\mathcal B(B_c \to J/\Psi\,l\,\nu)$, where $l \in (e,\,\mu)$, to be $0.71\pm0.17\pm 0.18$ which is at more than $2\sigma$ away from the standard model prediction. We investigate the anomalies in $R_D$, $R_{D^{\ast}}$, and $R_{J/\Psi}$ using a model independent framework with minimal number of new physics couplings. We find various new physics models that can explain these anomalies within $1\sigma$.