Theta-Induced Electric Dipole Moment of the Neutron via QCD Sum Rules

TL;DR

This paper calculates the neutron's electric dipole moment induced by the theta-angle using QCD sum rules, providing a theoretical estimate that constrains the theta parameter based on experimental bounds.

Contribution

The work introduces a QCD sum rule calculation of the neutron EDM induced by the theta-angle, refining the theoretical estimate and resulting constraints.

Findings

Neutron EDM estimated as 2.4 x 10^{-16} θ e.cm

Derived limit on theta: | heta|< 3 x 10^{-10}

Achieved approximately 40-50% precision in calculation

Abstract

Using the QCD sum rule approach, we calculate the electric dipole moment of the neutron induced by a vacuum theta--angle to approximately 40-50% precision, d_n = 2.4 x 10^{-16} \theta e.cm. Combined with the new experimental bound, this translates into the limit |\theta|< 3 x 10^{-10}.