CP-odd WWZ couplings induced by vector-like quarks

TL;DR

This paper investigates how adding vector-like quarks to the standard model can induce CP-odd WWZ couplings at one-loop level, with potential implications for new physics beyond the standard model.

Contribution

It provides the first estimate of CP-odd WWZ couplings induced by vector-like quarks, highlighting their potential magnitude and dependence on the quark content.

Findings

Form factors are estimated to be around 10^{-5}.

CP-odd couplings are larger than standard model predictions.

Couplings require both up-type and down-type extra quarks.

Abstract

A minimal extension of the standard model includes extra quarks with charges 2/3 and/or -1/3, whose left-handed and right-handed components are both SU(2) singlets. This model predicts new interactions of flavor-changing neutral current at the tree level, which also violate CP invariance. We study CP-odd anomalous couplings for the gauge bosons W, W, and Z induced by the new interactions at the one-loop level. These couplings become nonnegligible only if both an up-type and a down-type extra quarks are incorporated. Their form factors are estimated to be maximally of order $10^{-5}$. Such magnitudes are larger than those predicted in the standard model, though smaller than those in certain other models.