Vud from Nuclear Decays

TL;DR

This paper discusses methods for determining Vud from nuclear decays, emphasizing the importance of nuclear-structure calculations and testing their consistency using the CVC hypothesis, with shell model calculations performing best.

Contribution

It demonstrates that theoretical corrections in Vud determination can be tested for consistency using the CVC hypothesis, highlighting the shell model with Saxon-Woods functions as most effective.

Findings

Shell model calculations with Saxon-Woods functions perform best.

Theoretical corrections can be tested for consistency using CVC.

Nuclear results depend on isospin-symmetry breaking calculations.

Abstract

The current value of Vud is determined from superallowed beta-decay experiments. Other methods, briefly summarised here, have to overcome specific experimental hurdles before they are competitive. However, the nuclear results do depend on a nuclear-structure calculation of isospin-symmetry breaking, which is often a cause of some concern. We show here, by adopting the Conserved Vector Current (CVC) hypothesis, that these theoretical corrections can be tested for consistency. In this test, calculations based on the shell model with Saxon-Woods radial functions perform the best.