A strange contribution to the neutron EDM

TL;DR

This paper investigates how hypothetical quark electric dipoles, especially strange quarks, contribute to the neutron's electric dipole moment, highlighting their potential dominance beyond the Standard Model.

Contribution

It provides a comprehensive analysis combining perturbative QCD, large N expansion, and effective field theory to assess strange quark contributions to the neutron EDM.

Findings

Strange quark EDM can be about a tenth of valence quark EDMs.

Strange EDM may dominate neutron EDM in many beyond Standard Model scenarios.

Analysis suggests no significant cancellations in strange quark contributions.

Abstract

We analyze the contribution of hypothetical quark electric dipoles to the electric dipole moment (EDM) of the neutron. Particular emphasis is devoted to the strange quark contribution. Considerations based on perturbative QCD, the large N expansion, a critic reassessment of the non-relativistic quark model as well as a next to leading order calculation in heavy baryon effective field theory, all consistently indicate that, barring accidental cancellations, the matrix element of the strange quark dipole should be of order a tenth of those of the valence quarks. This implies that the strange EDM provides the dominant contribution to the neutron EDM in many scenarios beyond the Standard Model.