Model independent investigation of rare semileptonic b \to u l \bar{\nu}_l decay processes

TL;DR

This paper investigates potential lepton non-universality effects in rare semileptonic B meson decays involving b to u transitions, using a model-independent approach to constrain new physics parameters and predict observable effects.

Contribution

It introduces a model-independent analysis of b to u l nu decays, constraining new physics parameters and predicting branching ratios and asymmetries with potential lepton non-universality signals.

Findings

Constraints on new physics parameters from experimental branching fractions.

Predicted branching ratios and forward-backward asymmetries for B to P(V)l nu decays.

Identification of lepton non-universality parameters in these processes.

Abstract

Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions $b \to c l \bar{\nu}_l$, we intend to scrutinize the lepton non-universality effects in rare semileptonic $B$ meson decays involving the quark level transitions $b \to u l \bar{\nu}_l$. In this regard, we envisage the model-independent approach and consider the generalized effective Lagrangian in the presence of new physics and constrain the new parameters by using the experimental branching fractions of $B_u^+ \to l^+ \nu_l$ and $B^- \to \pi^0 \mu^- \bar \nu_\mu$ processes, where $l=e, \mu, \tau$. We then estimate the branching ratios and forward-backward asymmetries of $B_{(s)} \to P (V)l \bar{\nu}_l$ processes, where $P(=K, \pi, \eta^{(\prime)})$ denotes the pseudoscalar meson and $V(=K^*, \rho)$ is the vector meson. We also find out various lepton non-universality parameters in these processes in the presence of new physics.