Searching for physics beyond the Standard Model through the dipole interaction

TL;DR

This paper reviews how dipole interactions, especially electric and magnetic dipole moments, are crucial in probing physics beyond the Standard Model, highlighting recent experimental efforts and theoretical implications for new physics and symmetry violations.

Contribution

It provides an overview of dipole moment theory, experimental searches for EDMs, and their significance in discovering new physics beyond the Standard Model.

Findings

Muon anomalous magnetic moment exceeds Standard Model prediction.

Searches for electric dipole moments can reveal new sources of CP violation.

Experiments with polarized beams offer unique opportunities for detecting new physics.

Abstract

The magnetic dipole interaction played a central role in the development of QED, and continued in that role for the Standard Model. The muon anomalous magnetic moment has served as a benchmark for models of new physics, and the present experimental value is larger than the standard-model value by more than three standard deviations. The electric dipole moment (EDM) violates parity ({$P$}) and time-reversal ({$T$}) symmetries, and in the context of the $CPT$ theorem, the combination of charge conjugation and parity ($CP$). Since a new source of {$ CP$} violation outside of that observed in the $K$ and $B$ meson systems is needed to help explain the baryon asymmetry of the universe, searches for EDMs are being carried out worldwide on a number of systems. The standard-model value of the EDM is immeasurably small, so any evidence for an EDM would signify the observation of new physics. Unique opportunities exist for EDM searches using polarized proton, deuteron or muon beams in storage rings. This talk will provide an overview of the theory of dipole moments, and the relevant experiments. The connection to the transition dipole moment that could produce lepton flavor violating interactions such as $\mu^+ \rightarrow e^+ \gamma$ is also mentioned.