$R_D$ and $R_{D^{\ast }}$: Theoretical Development

Recent theoretical developments on $R_D$ and $R_{D^{\ast }}$ – discrepancies between experimental data and the Standard Model predictions have been reported (B anomaly) – are reviewed. New Physics explanations for the B anomaly and other relevant observables to obtain additional bounds on New Physics are also summarized. This is the proceedings for the talk at CIPANP2018 which was held on May 29 2018.