# The CKM parameters in the SMEFT

## TL;DR

This paper develops a comprehensive method to incorporate new physics effects from SMEFT into the extraction of CKM parameters, enabling more accurate flavor physics analyses beyond the Standard Model.

## Contribution

It introduces a general framework for including dimension-six SMEFT operators in CKM parameter determination, independent of specific new physics assumptions.

## Key findings

- Numerical CKM parameters with confidence intervals in SMEFT context
- Comparison of SMEFT-based CKM results with standard fits
- Practical examples of implementing the approach

## Abstract

The extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix from flavour observables can be affected by physics beyond the Standard Model (SM). We provide a general roadmap to take this into account, which we apply to the case of the Standard Model Effective Field Theory (SMEFT). We choose a set of four input observables that determine the four Wolfenstein parameters, and discuss how the effects of dimension-six operators can be included in their definition. We provide numerical values and confidence intervals for the CKM parameters, and compare them with the results of CKM fits obtained in the SM context. Our approach allows one to perform general SMEFT analyses in a consistent fashion, independently of any assumptions about the way new physics affects flavour observables. We discuss a few examples illustrating how our approach can be implemented in practice.