\(\Lambda _b \rightarrow p \tau \bar{\nu }\) Decay in  \(U_1\) Leptoquark Model

The measurements of several lepton flavor universality (LFU) violating observables in the decays induced by the quark level transition \(b \rightarrow c \tau \bar{\nu }\) provide the hint of physics beyond the standard model. These deviations can be resolved by adding a single vector leptoquark to the Standard Model. To further explore this leptoquark, we estimate the leverage of new physics in \(b \rightarrow c \tau \bar{\nu }\) on \(\Lambda _b \rightarrow p \tau \bar{\nu }\) decay in the context of \(U_1\) leptoquark model. In this model, the new physics couplings in \(b \rightarrow u \tau \bar{\nu }\) transition can be written in terms of \(b \rightarrow c \tau \bar{\nu }\) couplings and hence the extent of allowed new physics in \(\Lambda _b \rightarrow p \tau \bar{\nu }\) would be determined by \(b \rightarrow c \tau \bar{\nu }\) transition. The new physics parameter space is obtained by performing a fit to all \(b \rightarrow c \tau \bar{\nu }\) data and we obtain predictions of several \(\Lambda _b \rightarrow p \tau \bar{\nu }\) observables. We find that the current \(b \rightarrow c \tau \bar{\nu }\) data allows an order of magnitude enhancement in the branching ratio as well as in the LFU ratio. The other observables lepton forward-backward asymmetry, longitudinal polarization of tau lepton are consistent with the SM value.