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

Abstract

Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions $b\to cl{\bar{\nu }}_l$, we intend to scrutinize the lepton non-universality effects in rare semileptonic $B$ meson decays involving the quark level transitions $b\to ul{\bar{\nu }}_l$. 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 $V(=K^{\ast },\rho )$ is the vector meson. We also find out various lepton non-universality parameters in these processes in the presence of new physics.

Comments: 32 pages, 21 figures, to appear in Phys. Rev. D