Neutron Electric Dipole Moment Constraint on Scale of Minimal Left-Right Symmetric Model

TL;DR

This paper calculates the neutron electric dipole moment within the minimal left-right symmetric model to set new constraints on the scale of right-handed W-bosons, combining effective theory, renormalization group running, and experimental limits.

Contribution

It provides the first comprehensive calculation of nEDM in this model incorporating both explicit and spontaneous CP violations, leading to the most stringent bounds on the model's scale.

Findings

Left-right symmetry scale constrained to > 10 TeV

Incorporates state-of-the-art hadronic matrix elements

Uses combined nEDM and kaon decay data for limits

Abstract

Using an effective theory approach, we calculate the neutron electric dipole moment (nEDM) in the minimal left-right symmetric model with both explicit and spontaneous CP violations. We integrate out heavy particles to obtain flavor-neutral CP-violating effective Lagrangian. We run the Wilson coefficients from the electroweak scale to the hadronic scale using one-loop renormalization group equations. Using the state-of-the-art hadronic matrix elements, we obtain the nEDM as a function of right-handed W-boson mass and CP-violating parameters. We use the current limit on nEDM combined with the kaon-decay parameter $\epsilon$ to provide the most stringent constraint yet on the left-right symmetric scale $ M_{W_R} > (10 \pm 3) $ TeV.