New insights into the neutron electric dipole moment

TL;DR

This paper uses covariant baryon chiral perturbation theory to analyze the neutron's electric dipole moment, providing a new upper bound on the vacuum angle and comparing quark mass dependence with lattice QCD data.

Contribution

It offers a novel analysis of the neutron EDM within chiral perturbation theory and establishes a new upper limit on the vacuum angle | heta_0|.

Findings

New upper bound on | heta_0| \\lesssim 2.5 \\times 10^{-10}

Comparison of quark mass dependence with lattice QCD data

Matching between three- and two-flavor theories

Abstract

We analyze the CP-violating electric dipole form factor of the nucleon in the framework of covariant baryon chiral perturbation theory. We give a new upper bound on the vacuum angle, |\theta_0| \lesssim 2.5 \cdot 10^{-10}. The quark mass dependence of the electric dipole moment is discussed and compared to lattice QCD data. We also perform the matching between its representations in the three- and two-flavor theories.