Abstract
The deviations with respect to the Standard Model that are currently observed in b → sℓℓ transitions, or B anomalies, can be interpreted in terms of different New Physics (NP) scenarios within a model-independent effective approach. We identify a set of internal tensions of the fit that require further attention and whose theoretical or experimental nature could be determined with more data. In this landscape of NP, we discuss possible ways to discriminate among favoured NP hypotheses in the short term thanks to current and forthcoming observables. While an update of RK should help to disentangle the type of NP we may be observing (Lepton-Flavour Universality Violating and/or Lepton Flavour Universal), additional observables, in particular Q5, turn out to be central to determine which NP hypothesis should be preferred. We also analyse the preferences shown by the current global fit concerning various NP hypotheses, using two different tools: the behaviour of the pulls of individual observables under NP scenarios and the directions favoured by approximate quadratic parametrisations of the observables in terms of Wilson coefficients.
Highlights
In b → s decays, with pulls w.r.t. the SM ranging from 5.3σ to 5.9σ
We analyse the preferences shown by the current global fit concerning various New Physics (NP) hypotheses, using two different tools: the behaviour of the pulls of individual observables under NP scenarios and the directions favoured by approximate quadratic parametrisations of the observables in terms of Wilson coefficients
Most scenarios discussed in the literature assumed that there is NP in muons only, i.e. the LFUV-NP contributions come from allowing the presence of NP in the muon channel and not in the electron one
Summary
In refs. [3, 4], we saw that different NP scenarios involving C9NμP led to a much better description of the data than the SM, with fits reaching p-values around 60–80% (the SM being around 9%) and providing pulls with respect to the SM above 5σ. The recent Belle measurement [2] indicates a low central value in the same bin, even though the large uncertainty affecting the measurement prevents us from drawing any definite conclusion and makes it compatible with the SM Another approach to slightly reduce the tension between data and SM in the first bin of RK∗ through a NP explanation consists in including NP contributions to the b → see channel, in particular, considering right-handed currents affecting electrons, as discussed in ref. Data shows the opposite trend, which may come from a statistical fluctuation of the data leading to an inversion of the experimental measurements of both modes at large recoil This issue may signal a problem in the theoretical prediction of the form factors of ref. The impact on efficiencies from NP effects was considered in ref. [36] for Bs → φμ+μ− by varying C9μ in the underlying physics model used to compute signal efficiencies, leading to a much smaller effect in this case (of a few percent, in line with back-of-the-envelope estimates)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
