Impact of Neutron Decay Experiments on non-Standard Model Physics

TL;DR

This paper reviews how neutron beta decay experiments constrain physics beyond the Standard Model, highlighting recent advances and their implications for new physics searches, including right-handed currents and scalar/tensor interactions.

Contribution

It provides an overview of current and future limits on non-Standard Model physics from neutron decay measurements, emphasizing their role in exploring extensions to the Standard Model.

Findings

Neutron decay observables can over-determine the SM parameters.

Recent experiments improve constraints on right-handed currents.

Neutron decay studies complement high-energy physics searches.

Abstract

This paper gives a brief overview of the present and expected future limits on physics beyond the Standard Model (SM) from neutron beta decay, which is described by two parameters only within the SM. Since more than two observables are accessible, the problem is over-determined. Thus, precise measurements of correlations in neutron decay can be used to study the SM as well to search for evidence of possible extensions to it. Of particular interest in this context are the search for right-handed currents or for scalar and tensor interactions. Precision measurements of neutron decay observables address important open questions of particle physics and cosmology, and are generally complementary to direct searches for new physics beyond the SM in high-energy physics. Free neutron decay is therefore a very active field, with a number of new measurements underway worldwide. We present the impact of recent developments.