Calculation of neutron electric dipole moment due to the QCD topological term, Weinberg three-gluon operator and the quark chromoelectric moment

TL;DR

This paper computes the neutron electric dipole moment contributions from gluonic CP violation and quark chromoelectric moments using lattice QCD techniques, providing continuum results and addressing operator mixing issues.

Contribution

It introduces a lattice QCD approach to calculate the neutron EDM from dimension 4 and 6 gluonic operators and quark chromoelectric moments, with nonperturbative control of divergences.

Findings

Results for the neutron EDM from gluonic operators using gradient flow.

Analysis of the quark chromoelectric operator and divergence control.

Continuum extrapolated values for CP-violating contributions.

Abstract

We present results for the neutron electric dipole moment due to the dimension 4 and dimension 6 gluonic CP violation, and the isovector quark chromoelectric dipole moment using clover valence quarks on HISQ dynamical ensembles generated by the MILC Collaboration. For the gluonic operators, we use the gradient flow scheme to obtain divergence-free continuum results. For the chromoelectric dipole moment operator, we use the unflowed local operator but discuss how the quadratically divergent mixing with the pseudoscalar operator can be controlled nonperturbatively.