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 $0.71\pm 0.17\pm 0.18$ 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 $1\sigma$.

Comments: 9 pages, 2 figures