The quest to find an electric dipole moment of the neutron

TL;DR

This paper reviews the ongoing efforts and scientific significance of searching for the neutron's electric dipole moment, a key indicator of CP violation with implications for understanding matter-antimatter asymmetry.

Contribution

It provides a comprehensive overview of the concepts, experimental approaches, and global efforts in the search for the neutron EDM, highlighting its importance in fundamental physics.

Findings

No neutron EDM has been observed yet.

The neutron EDM is a sensitive probe for CP violation.

Discovering the neutron EDM could explain matter-antimatter asymmetry.

Abstract

Until now no electric dipole moment of the neutron (nEDM) has been observed. Why it is so vanishingly small, escaping detection for the last 65 years, is not easy to explain. In general it is considered as one of the most sensitive probes for the violation of the combined symmetry of charge and parity (CP). A discovery could shed light on the poorly understood matter/antimatter asymmetry of the Universe. The neutron EDM might one day help to distinguish different sources of CP-violation in combination with measurements of paramagnetic molecules, diamagnetic atoms and other nuclei. This review presents an overview of the most important concepts in searches for an nEDM as well as a brief overview of the worldwide efforts.