Abstract
Motivated by deviations with respect to Standard Model predictions in b→sℓ+ℓ− decays, we evaluate the global significance of the new physics hypothesis in this system by including the look-elsewhere effect for the first time. We estimate the trial-factor with pseudo-experiments and find that it can be as large as seven. We calculate the global significance for the new physics hypothesis by considering the most general description of a non-standard b→sℓ+ℓ− amplitude of short-distance origin. Theoretical uncertainties are treated in a highly conservative way by absorbing the corresponding effects into a redefinition of the Standard Model amplitude. Using the most recent measurements of LHCb, ATLAS and CMS, we obtain the global significance to be 4.3 standard deviations.
Highlights
Since 2013, several measurements have shown deviations from Standard Model (SM) predictions in rare bhadron decays controlled by the underlying quark-level transition b → s + − ( = e, μ) [1,2,3,4,5,6,7,8,9,10]
Summarizing, the approach we propose to determine the statistical significance of NP in b → s + − transitions is based on the following points:
The same procedure is used in data, obtaining a ∆χ2 = 31.4, which corresponds to a global significance of 4.3σ
Summary
By short-distance we mean a NP interaction which appears as a local interaction in b-hadron decays This general hypothesis, which is well justified by the absence of non-SM particles observed so far at colliders, allows us to describe b → s + − transitions using the general formalism of effective Lagrangians, encoding a hypothetical NP contribution via appropriate four-fermion operators. This description, which is conceptually similar to Fermi’s theory of beta decays [12], allows to consider each specific bhadron decay of interest as a different way to probe the same underlying b → s + − short-distance interaction
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