Quark unitarity triangles

TL;DR

This paper analyzes the angles of all unitarity triangles of the CKM matrix using experimental data, testing the unitarity predictions and exploring the consistency of the Standard Model with observed measurements.

Contribution

It provides a parameterization-independent analysis of unitarity triangle angles and resolves inconsistencies in side lengths through a constrained fit assuming equal areas.

Findings

Data are compatible with CKM unitarity predictions.

A 2σ tension exists for one unitarity triangle.

Angles from row and column multiplications are consistent.

Abstract

The angles of all unitarity triangles of the Cabibbo-Kobayashi-Maskawa matrix are determined from the experimental data. Our analysis is independent of the parameterization of the CKM matrix and it is based on the predictions of the unitarity for the angles and the areas of the unitarity triangles. We note that the lengths of the sides of the four unitarity triangles determined from the experimental data do not form a triangle. We resolve this incompatibility by performing a constrained fit, assuming the equality of the area of the unitarity triangles. We demonstrate that the measured data are compatible with the predictions of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, but there is a $2\sigma$ tension for one of the triangles. We show that the angles of the unitarity triangles obtained by the multiplication of the rows of the CKM matrix can be obtained from the angles obtained by the multiplication of the columns. The equality of those two types of the angles is a simple, but a very powerful test of the general structure of the Standard Model.