Probing Lepton Universality with (Semi)-Leptonic B decays

2018/12/12 by Banelli, Giovanni, Fleischer, Robert, Jaarsma, Ruben +1 · 1 citation
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.1812.05200

Abstract

The most recent measurements of the observables R_D^(*) are in tension with the Standard Model offering hints of New Physics in b→ c ℓ ν_ℓ transitions. Motivated by these results, in this work we present an analysis on their b→ u ℓ ν_ℓ counterparts (for ℓ=e, ~μ, ~τ). Our study has three main objectives. Firstly, using ratios of branching fractions, we assess the effects of beyond the Standard Model scalar and pseudoscalar particles in leptonic and semileptonic B decays (B^-→ ℓ^- ν_ℓ, B→ πℓ ν_ℓ and B→ ρℓ ν_ℓ). Here a key role is played by the leptonic B processes, which are highly sensitive to new pseudoscalar interactions. In particular, we take advantage of the most recent measurement of the branching fraction of the channel B^-→ μ^-ν_μ by the Belle collaboration. Secondly, we extract the CKM matrix element |V_ub| while accounting simultaneously for New Physics contributions. Finally, we provide predictions for the branching fractions of yet unmeasured leptonic and semileptonic B decays.

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