# 2019 CAP Congress / Congrès de l'ACP 2019

2-7 June 2019
Simon Fraser University
America/Vancouver timezone
Welcome to the 2019 CAP Congress Program website! / Bienvenue au siteweb du programme du Congrès de l'ACP 2019 !

## An Improved Extraction of the Vud CKM Matrix Element

Jun 6, 2019, 2:15 PM
15m
SSB 7172 (Simon Fraser University)

### SSB 7172

#### Simon Fraser University

Oral not-in-competition (Graduate Student) / Orale non-compétitive (Étudiant(e) du 2e ou 3e cycle) Theoretical Physics / Physique théorique (DTP-DPT)

### Speaker

Mr Kyle Shiells (University of Manitoba)

### Description

The CKM matrix of the Standard Model (SM) is a unitary $3\times3$ matrix which holds information on how strongly the various quark flavours couple to each other. Consequently, nature’s adherence to the SM can be tested by the normalization condition of its rows. $|V_{ud}| = 0.97417(21)$ is a dominant term in the first row unitarity condition: $|V_{ud}|^2 + |V_{us}|^2 + |V_{ub}|^2 = 1$, and thus carries more weight than its 2 neighbours. The largest source of its uncertainty comes from a troublesome, model-dependent radiative correction: the $\gamma W$ box. I outline a new way to calculate this Feynman diagram using dispersion relations, which lead to a more realistic value of $V_{ud}$ and its uncertainty estimate.

### Primary author

Mr Kyle Shiells (University of Manitoba)