Microscopic calculations of isospin-breaking corrections to superallowed beta-decay

TL;DR

This paper uses advanced nuclear density functional theory to calculate isospin-breaking corrections in superallowed beta-decay, refining the determination of the CKM matrix element |V_{ud}| and testing the Standard Model.

Contribution

It introduces a self-consistent isospin- and angular-momentum-projected density functional approach for the first time to compute these corrections.

Findings

Calculated |V_{ud}| value aligns with recent experimental results.

Provides improved theoretical estimates of isospin-breaking effects.

Supports the validity of the Standard Model through precise nuclear decay analysis.

Abstract

The superallowed beta-decay rates that provide stringent constraints on physics beyond the Standard Model of particle physics are affected by nuclear structure effects through isospin-breaking corrections. The self-consistent isospin- and angular-momentum-projected nuclear density functional theory is used for the first time to compute those corrections for a number of Fermi transitions in nuclei from A=10 to A=74. The resulting leading element of the CKM matrix, |V_{ud}|= 0.97447(23), agrees well with the recent result by Towner and Hardy [Phys. Rev. C {\bf 77}, 025501 (2008)].