The Neutron Lifetime

TL;DR

This paper reviews the importance of the neutron lifetime in understanding weak interactions, highlights the current experimental disagreement, and discusses future prospects for resolving this discrepancy.

Contribution

It provides a comprehensive overview of the neutron lifetime, its significance in physics, and discusses the experimental challenges and future directions to resolve measurement discrepancies.

Findings

Current experimental methods disagree by almost 4 sigma.

Neutron lifetime impacts CKM matrix element Vud determination.

Future experiments aim to resolve measurement discrepancies.

Abstract

The decay of the free neutron into a proton, electron, and antineutrino is the prototype semileptonic weak decay and the simplest example of nuclear beta decay. The nucleon vector and axial vector weak coupling constants G_V and G_A determine the neutron lifetime as well as the strengths of weak interaction processes involving free neutrons and protons that are important in astrophysics, cosmology, solar physics and neutrino detection. In combination with a neutron decay angular correlation measurement, the neutron lifetime can be used to determine the first element of the CKM matrix Vud. Unfortunately the two main experimental methods for measuring the neutron lifetime currently disagree by almost 4 sigma. I will present a brief review of the status of the neutron lifetime and prospects for the future.