Model independent investigation of rare semileptonic b \to u l \barν_l decay processes

Abstract

Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions $b \to c l \barν_l$, we intend to scrutinize the lepton non-universality effects in rare semileptonic $B$ meson decays involving the quark level transitions $b \to u l \barν_l$. 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 $B_u^+ \to l^+ ν_l$ and $B^- \to π^0 μ^- \bar ν_μ$ processes, where $l=e, μ, τ$. We then estimate the branching ratios and forward-backward asymmetries of $B_{(s)} \to P (V)l \barν_l$ processes, where $P(=K, π, η^{(\prime)})$ denotes the pseudoscalar meson and $V(=K^*, ρ)$ is the vector meson. We also find out various lepton non-universality parameters in these processes in the presence of new physics.