Cornering New Physics in b --> s Transitions

TL;DR

This paper derives updated constraints on new physics operators affecting b --> s transitions using recent measurements of rare B meson decays, finding good agreement with the Standard Model and tighter bounds on certain operators.

Contribution

It provides the first comprehensive analysis including all relevant observables and chirality-flipped operators, updating constraints with recent experimental data.

Findings

Good agreement with Standard Model expectations.

Significantly tighter constraints on chirality-flipped coefficients.

Identification of observables sensitive to new physics in low recoil B --> K* mu+mu-.

Abstract

We derive constraints on Wilson coefficients of dimension-six effective operators probing the b --> s transition, using recent improved measurements of the rare decays Bs --> mu+mu-, B --> K mu+mu- and B --> K* mu+mu- and including all relevant observables in inclusive and exclusive decays. We consider operators present in the SM as well as their chirality-flipped counterparts and scalar operators. We find good agreement with the SM expectations. Compared to the situation before winter 2012, we find significantly more stringent constraints on the chirality-flipped coefficients due to complementary constraints from B --> K mu+mu- and B --> K* mu+mu- and due to the LHCb measurement of the angular observable S_3 in the latter decay. We also list the full set of observables sensitive to new physics in the low recoil region of B --> K* mu+mu-.