Lepton nonuniversality in exclusive $b{\rightarrow}s{\ell}{\ell}$ decays
Résumé
The LHCb measurements of certain ratios of decay modes testing lepton flavor nonuniversality might open an exciting world of new physics beyond the standard model. The latest LHCb measurements of RK* offer some new insight beyond the previous measurement of RK. We work out the present significance for nonuniversality, and argue that claims of 5σ deviations from the standard model based on all present b→sℓ+ℓ- data including the ratios are misleading and are at present still based on guesstimates of hadronic power corrections in the b→sℓ+ℓ- angular observables. We demonstrate that only a small part of the luminosity of 50 fb-1 foreseen to be accumulated by the LHCb will be needed to offer soon a definite answer to the present question of whether we see a very small glimpse of lepton flavor nonuniversal new physics or not. We also present new predictions for other ratios based on our analysis of the present measurements of the ratios RK(*) and analyze if they are able to differentiate between various new physics options within the effective field theory at present or in the near future.
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