### INT Workshop INT-19-75W

## Fundamental Symmetries Research with Beta Decay

### November 4 - 8, 2019

## Overview

This is a five day workshop to identify and assess the global, current and planned beta decay research over the next five to ten years. The impact of these measurements is defined by theoretical work in diverse areas of nuclear and particle theory, including conventional nuclear structure, electroweak radiative corrections, lattice calculations of nucleon properties and high energy phenomenology. Recent progress in all of these areas has generated a new understanding of the challenges and opportunities for improved experimental limits on BSM physics. In this workshop we will bring together all major beta decay groups and representatives from these four areas of theory to help identify the most promising avenues for new BSM searches, and the resources (both in theory and experiment) to successfully perform these searches. A white paper will be produced during and after the workshop to collect and summarize the results of our discussion.

Two preceding meetings, Beta Decay as a Probe of New physics at the Amherst Center for Fundamental Interactions on November 1-3, 2018 and Precise Beta Decay Calculations for Searches for New Physics at the European Center for Theoretical Nuclear Physics in Trento on April 8-12, 2019, have helped to sharpen the issues and strategies for the development of theory. In this meeting, the goal is to merge the proposed theoretical activity with a critical assessment of the experimental program for its motivation and impact, and to identify new opportunities, both in theory and experiment to push for more stringent constraints. We will also discuss recent efforts to incorporate the results of low energy precision tests with LHC results in particle physics compilations such as FLAVIAnet.

## Topics

- The status of constraints on BSM physics from low energy probes and from the LHC
- Experimental status of the superallowed decays
- The electroweak radiative corrections in neutrons and nuclei
- Angular correlations and lifetime measurements of the neutron
- New techniques to measure the beta spectrum in nuclear and neutron decays
- Ab initio and EFT methods for calculating high precision wave functions and matrix elements
- Experiments and impact of mirror nuclei on BSM searches
- New experimental techniques for trapping cold atoms, ions, and neutrons
- Progress on lattice QCD for nuclei and operators
- Time reversal invariance and beta decay
- Facilities for beta decay experiments