A formalism to assess the accuracy of nuclear-structure weak interaction effects in precision $\beta$-decay studies

TL;DR

This paper develops a formalism for precise theoretical predictions of nuclear $eta$-decay observables, incorporating high-order corrections and analyzing uncertainties to support searches for physics beyond the Standard Model.

Contribution

It introduces a perturbative formalism with controlled accuracy for $eta$-decay calculations, including high order nuclear recoil and shape corrections, addressing the needs of current precision experiments.

Findings

Hierarchical small parameters for correction accuracy

Sub-percent experimental uncertainties require ~10 ext{%} nuclear theory accuracy

Feasible for light to medium nuclei with modern nuclear theory

Abstract

Multiple high precision $\beta$-decay measurements are being carried out these days on various nuclei, in search of beyond the Standard Model signatures. These measurements necessitate accurate standard model theoretical predictions to be compared with. Motivated by the experimental surge, we present a formalism for such a calculation of $\beta$-decay observables, with controlled accuracy, based on a perturbative analysis of the theoretical observables related to the phenomena, including high order nuclear recoil and shape corrections. The accuracy of the corrections is analyzed by identifying a hierarchy of small parameters, related to the low momentum transfer characterizing $\beta$-decays. Furthermore, we show that the sub-percent uncertainties, targeted by on-going and planned experiments, entail an accuracy of the order of 10\% for the solution of the nuclear many body problem, which is well within the reach of modern nuclear theory for light to medium mass nuclei.