Resolving the Flavor Structure in the MFV-SMEFT

TL;DR

This paper performs a comprehensive global analysis to constrain the flavor structure of Wilson coefficients in the SMEFT, leveraging data from multiple experiments to resolve flavor symmetry breaking sources.

Contribution

It introduces a novel combined fit approach that uses high- and low-energy data to fully resolve flavor structures in SMEFT without blind spots.

Findings

Successfully constrains flavor-breaking Wilson coefficients.

Demonstrates the method's applicability beyond MFV, including other flavor symmetries.

Identifies the importance of combined sector analysis for complete flavor structure resolution.

Abstract

We constrain the flavor structure of Wilson coefficients in the Standard Model Effective Field Theory (SMEFT) from data. In the SMEFT, new physics effects in couplings of up-type and down-type quarks are related through the Cabibbo-Kobayashi-Maskawa mixing matrix. We exploit this relation to pin down potential new sources of flavor symmetry breaking in a global analysis of high- and low-energy data from the LHC, LEP, and $b$ factory experiments. We demonstrate the power of such an analysis by performing a combined fit of effective four-quark and two-quark couplings contributing to a large set of flavor, top-quark, electroweak, and dijet observables. All four sectors are needed to fully resolve the flavor structure of the four-quark couplings without leaving blind directions in the parameter space. Although we work in the framework of minimal flavor violation, our strategy applies as well to other flavor patterns, like $U(2)$ flavor symmetry or leptoquark scenarios.