A closer look at observables from exclusive semileptonic $B\to (\pi ,\rho )\ell {\nu }_{\ell }$ decays

Abstract

This article analyses the available inputs in $\text{btopilnu}$ and $\text{btorholnu}$ decays which include the measured values of differential rate in different $q^2$-bins (lepton invariant mass spectrum), lattice, and the newly available inputs on the relevant form-factors from the light-cone sum rules (LCSR) approach. We define different fit scenarios, and in each of these scenarios, we predict a few observables in the standard model (SM). For example, $R(M)=\frac{\mathcal{B}(B\to M{\ell }_i{\nu }_{{\ell }_i})}{\mathcal{B}(B\to M{\ell }_j{\nu }_{{\ell }_j})}$, $R_{{\ell }_j}^{{\ell }_i}(M)=\frac{\mathcal{B}(B\to {\ell }_i{\nu }_{{\ell }_i})}{\mathcal{B}(B\to M{\ell }_j{\nu }_{{\ell }_j})}$ with M = $\pi$ or $\rho$ and ${\ell }_{i,j}=e,\mu$ or $\tau$. We also discuss the new physics (NP) sensitivities of all these observables and obtain bounds on a few NP Wilson coefficients in $b\to u\tau {\nu }_{\tau }$ decays using the available data. We have noted that the data at present allows sizeable NP contributions in this mode. Also, we have predicted a few angular observables relevant to these decay modes.

Comments: Version to be published in JHEP