Patterns of New Physics in $b o s\ell^+\ell^-$ transitions in the light of recent data

摘要

In the Standard Model (SM), the rare transitions where a bottom quark decaysinto a strange quark and a pair of light leptons exhibit a potentialsensitivity to physics beyond the SM. In addition, the SM embeds Lepton FlavourUniversality (LFU), leading to almost identical probabilities for muon andelectron modes. The LHCb collaboration discovered a set of deviations from theSM expectations in decays to muons and also in ratios assessing LFU. Otherexperiments (Belle, ATLAS, CMS) found consistent measurements, albeit withlarge error bars. We perform a global fit to all available $b\to s\ell^+\ell^-$data ($\ell=e,\mu$) in a model-independent way allowing for different patternsof New Physics. For the first time, the NP hypothesis is preferred over the SMby $5\,\sigma$ in a general case when NP can enter SM-like operators and theirchirally-flipped partners. LFU violation is favoured with respect to LFU at the3-4$\,\sigma$ level. We discuss the impact of LFU-violating New Physics on theobservable $P_5^\prime$ from $B \to K^*\mu^+\mu^-$ and we compare our estimatefor long-distance charm contributions with an empirical model recently proposedby a group of LHCb experimentalists. Finally, we discuss NP models able todescribe this consistent pattern of deviations.