Patterns of New Physics in b → sℓ+ℓ− transitions in the light of recent data

By B. Capdevila, Andreas Crivellin, S. Descotes-Genon, J. Matias, J. Virto. Journal of High Energy Physics, 2017

421 citations recorded by the source corpus.

In the Standard Model (SM), the rare transitions where a bottom quark decays into a strange quark and a pair of light leptons exhibit a potential sensitivity to physics beyond the SM. In addition, the SM embeds Lepton Flavour Universality (LFU), leading to almost identical probabilities for muon and electron modes. The LHCb collaboration discovered a set of deviations from the SM expectations in decays to muons and also in ratios assessing LFU. Other experiments (Belle, ATLAS, CMS) found consistent measurements, albeit with large error bars. We perform a global fit to all available b → sℓ+ℓ− data (ℓ = e, μ) in a model-independent way allowing for different patterns of New Physics. For the first time, the NP hypothesis is preferred over the SM by 5 σ in a general case when NP can enter SM-like operators and their chirally-flipped partners. LFU violation is favoured with respect to LFU at the 3-4 σ level. We discuss the impact of LFU-violating New Physics on the observable P5′ from B → K∗μ+μ− and we compare our estimate for long-distance charm contributions with an empirical model recently proposed by a group of LHCb experimentalists. Finally, we discuss NP models able to describe this consistent pattern of deviations.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/8734b1d29db4443a01f162541c15257824cf52bd

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Citations in the corpus

Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era (2018, positive): “2 Search for D → hμ+μ− and Λ+c → pμ+μ− decays As already stated b→ s`+`− electroweak penguin transitions have proven to be powerful tools to search for New Physics effects [310,311].”
Maximal flavour violation: a Cabibbo mechanism for leptoquarks (2018, neutral): “Combining the experimental measurements of LFU observables in b → s`` transitions yields the following preferred region for the non-universal NP effect [78] (see also [79–84])”
Addendum to: Emerging patterns of New Physics with and without Lepton Flavour Universal contributions (2019, methodology): “(1) On the one hand, only one of the anomalous bins in P ′ 5 ([4, 6]) sees its individual significance marginally decreased from 2.”
New physics in b → s μ + μ − after the measurement of R K * (2017, positive): “[18], namely we simultaneously included both B(B → K(∗)0μ+μ−) and R K in the fit.”