On the significance of new physics in $b\to s\ell^+\ell^-$ decays

TL;DR

This paper assesses the global significance of potential new physics in $b\to s\ell^+\ell^-$ decays, accounting for the look-elsewhere effect, and finds a 4.3 sigma deviation from the Standard Model using recent collider data.

Contribution

It introduces a comprehensive evaluation of the global significance of new physics signals in $b\to s\ell^+\ell^-$ decays, including the look-elsewhere effect and a conservative treatment of uncertainties.

Findings

Global significance of new physics is 4.3 sigma.

Look-elsewhere effect trial factor can be as high as seven.

Conservative uncertainty treatment supports the significance estimate.

Abstract

Motivated by deviations with respect to Standard Model predictions in $b\to s\ell^+\ell^-$ decays, we evaluate the global significance of the new physics hypothesis in this system by including the {\it 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 $b\to s\ell^+\ell^-$ 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.