Vector-like quark doublets, weak-basis invariants and CP violation

TL;DR

This paper investigates extensions of the Standard Model with vector-like quark doublets, focusing on their impact on CP violation, parameterization, and phenomenology, including potential explanations for Cabibbo angle anomalies.

Contribution

It provides a comprehensive analysis of CP violation invariants and parameterizations in models with vector-like quark doublets, linking weak-basis invariants to standard quark rephasing invariants.

Findings

Identifies minimal parameter sets for vector-like quark extensions.

Derives a complete set of CP-odd invariants for the single doublet case.

Establishes a connection between weak-basis invariants and standard quark rephasing invariants.

Abstract

We study Standard Model extensions with isodoublet vector-like quarks with standard charges. Their presence induces right-handed charged and neutral currents. We identify minimal sets of independent parameters characterizing these extensions, describe useful weak bases, and provide parameterizations for all quark mixing. We analyze the intricacies of CP violation in such scenarios, finding a complete set of CP-odd invariants for the single doublet case. Crucially, we uncover a connection between weak-basis invariants and effective rephasing invariants involving only standard quarks. These results allow us to explore the phenomenology of doublet vector-like quarks through a rephasing-invariant analysis, with an emphasis on CP violation, including the potential role of these fields in explaining the Cabibbo angle anomalies.