Neutron EDM in Four Generation Standard Model

TL;DR

This paper estimates the neutron electric dipole moment within a four-generation Standard Model, considering various contributions, and finds it to be below current experimental detection capabilities.

Contribution

It provides a detailed estimation of the neutron EDM in a four-generation model, including electroweak and gluonic contributions, with implications for future experiments.

Findings

Neutron EDM estimated around 10^{-31} e cm

Dominated by strange quark chromoelectric dipole moment

Current and planned experiments are not sensitive enough to detect this EDM

Abstract

A fourth generation of quarks, if it exist, may provide sufficient CP violation for the baryon asymmetry of the Universe. We estimate the neutron electric dipole moment in the presence of a fourth generation, and find it would be dominated by the strange quark chromoelectric dipole moment, assuming it does not get wiped out by a Peccei-Quinn symmetry. Both the three electroweak loop and the two-loop electroweak/one-loop gluonic contributions are considered. With m_{b'}, m_{t'} at 500 GeV or so that can be covered at the LHC, and with a Jarlskog CPV factor that is consistent with hints of New Physics in b to s transitions, the neutron EDM is found around 10^{-31}e cm, still far below the 10^{-28}e cm reach of the new experiments being planned or under construction.