On flavourful Easter eggs for New Physics hunger and lepton flavour universality violation.

Within the standard approach of effective field theory of weak interactions for Δ B = 1 transitions, we look for possibly unexpected subtle New Physics effects, here dubbed "flavourful Easter eggs". We perform a Bayesian global fit using the publicly available HEPfit package, taking into account state-of-the-art experimental information concerning these processes, including the suggestive measurements from LHCb of R K and R K ∗ , the latter available only very recently. We parametrise New Physics contributions to b → s transitions in terms of shifts of Wilson coefficients of the electromagnetic dipole and semileptonic operators, assuming CP-conserving effects, but allowing in general for violation of lepton flavour universality. We show how optimistic/conservative hadronic estimates can impact quantitatively the size of New Physics extracted from the fit. With a conservative approach to hadronic uncertainties we find nonzero New Physics contributions to Wilson coefficients at the level of ∼ 3 σ , depending on the model chosen. Furthermore, given the interplay between hadronic contributions and New Physics effects in the leptonic vector current, a scenario with nonstandard leptonic axial currents is comparable to the more widely advocated one with New Physics in the leptonic vector current.

Direct CP violation in B-->phiKs and new physics.

In the presence of large new physics contributions to loop-induced b-->s transitions, sizable direct CP violation in B-->phiK decays is expected on general grounds. We compute explicitly CP-violating effects using QCD factorization and find that, even in the restricted case in which new physics has the same penguin structure as the standard model, the rate asymmetry can be of the order of 1. We briefly discuss a more general scenario and comment on the inclusion of power-suppressed corrections to factorization.