Searching for New Physics in the Differential Decay Width of a Lambda_b Semi-leptonic Decay

We propose to investigate the effects of new physics in the semi-leptonic sequential decay ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c(\to \mathrm{\Lambda }\pi )\tau {\bar{\nu }}_{\tau }$. Firstly, we write the general, model independent, non-covariant expression of the differential decay width of the process. Then, we calculate that observable according to three different types of new physics interactions, which might explain the tension of data with the standard model predictions. We find that some coefficients of the differential decay width are sensitive to the kind of interaction that is assumed. The measurements that we suggest seem to be feasible.