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 Delta 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 similar to 3 sigma, 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.