Exploring Right-Handed Neutrinos as Probes of New Physics in Semileptonic $\bar{B}$ Decays

Evidence for New Physics (NP) has been observed in charged current decays of \( B \to D^* \ell \bar{\nu} \), as measured by the BaBar, Belle, and LHCb experiments. The experimental results indicate that $R_{D^*}$ surpasses the predictions of the Standard Model (SM), with the deviation reaching a combined significance of $3.4\sigma$. In this work, we investigate the differential decay distributions of \( \bar{B} \to D^* \ell \bar{X} \), where \( X \) is a heavy right-handed neutrino. To explore NP signatures associated with such a heavy neutrino, we employ a newly developed Monte Carlo event generator built upon the EvtGen framework, used specifically to simulate beyond-the-standard model processes. Angular and kinematic distributions from EvtGen generator offer a systematic way to probe the right-handed neutrino signatures in heavy-flavor decays, offering sensitive tests of New Physics(NP).