In recent times, several hints of lepton nonuniversality have been observed in semileptonic B meson decays, both in the charged-current (b → clν l ) and neutral-current (b → sll) transitions. Motivated by these intriguing results, we perform a model-independent analysis of the semileptonic Λ b decays involving the quark level transitions b → ðu; cÞlν l , in order to scrutinize the nature of new physics. We constrain the new parameter space by using the measured branching ratios of the B þ c;u → τ þ ν τ , B → πτν τ processes and the existing experimental results on the R D ðÃÞ , R J=ψ , and R l π parameters. Using the constrained parameters, we estimate the branching ratios, forward-backward asymmetries, and hadron and lepton polarization asymmetries of the Λ b → ðΛ c ; pÞlν l processes. Moreover, we also examine whether there could be any lepton universality violation in these decay modes.

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Very compelling deviations in the recently observed lepton nonuniversality observables (R D (*) , R K (*) , R J/ψ) of semileptonic B meson decays from their Standard Model predictions hint towards the presence of some kind of new physics beyond it. In this regard, we investigate the effect of new physics in the semileptonicB * d(s) → P ν decay processes, where P = D, π(D s , K), in a model independent way. We consider the presence of additional vector and scalar type interactions and constrain the corresponding new couplings by fitting Br(B + u → τ + ν τ), Br(B → πτν τ), Br(B + c → τ + ν τ), R l π , R D (*) and R J/ψ data. Using the constrained new parameters, we estimate the branching ratios, forward-backward asymmetry, lepton-spin asymmetry and lepton non-universality observables ofB * d,s → Pτν τ processes. We find that the branching ratios of these decay modes are sizeable and deviate significantly (for vector-type couplings) from their corresponding standard model values, which are expected to be within the reach of Run III of Large Hadron Collider experiment.

Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions b → clν l , we intend to scrutinize the lepton non-universality effects in rare semileptonic B meson decays involving the quark level transitions b → ulν 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 → l + ν l and B − → π 0 µ −ν µ processes, where l = e, µ, τ . We then estimate the branching ratios and forward-backward asymmetries of B (s) → P (V )lν l processes, where P (= K, π, η ( ) ) 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.

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