Exploring New Physics in the C7-C7' plane

TL;DR

This paper systematically constrains the Wilson coefficient C7 in B meson decays, considering experimental data and exploring potential new physics effects, including sign flips and chirality changes.

Contribution

It introduces a comprehensive approach to constrain C7 and related coefficients using multiple observables, extending the analysis to include flipped-sign solutions and chirality-flipped operators.

Findings

The standard model solution for C7 shows mild tension with data.

Constraints on C7 need to be extended up to 1.6 sigma for flipped-sign solutions.

Semi-numerical expressions for observables as functions of Wilson coefficients are provided.

Abstract

The Wilson coefficient C7 governing the radiative electromagnetic decays of B meson has been calculated to a very high accuracy in the Standard Model, but experimental bounds on either the magnitude or the sign of C7 are often model-dependent. In the present paper, we attempt at constraining both the magnitude and sign of C7 using a systematic approach. We consider already measured observables like the branching ratios of B \rightarrow Xs mu+ mu- and B \rightarrow Xs gamma, the isospin and CP asymmetries in B \rightarrow K* gamma, as well as AFB and FL in B \rightarrow K*l+l-. We also discuss the transverse observable AT2 which, once measured, may help to disentangle some of the scenarios considered. We explore the constraints on C7, C9, C10 as well as their chirality-flipped counterparts. Within our framework, we find that we need to extend the constraints up to 1.6 sigma to allow for the "flipped-sign solution" of C7. The SM solution for C7 exhibits a very mild tension if New Physics is allowed in dipole operators only. We provide semi-numerical expressions for all these observables as functions of the relevant Wilson coefficients at the low scale.