Constraints on the quark mixing matrix with vector-like quarks

TL;DR

This paper examines how adding vector-like quarks to the Standard Model affects quark mixing constraints, showing they remain viable extensions compatible with current experimental data.

Contribution

It provides new constraints on mixing angles and phases of vector-like quarks using flavor-changing processes, expanding understanding of their possible interactions.

Findings

Constraints on mixing angles and phases derived from B-meson processes

Vector-like quarks can extend the Standard Model without anomalies

Compatibility with electroweak precision tests confirmed

Abstract

While a chiral fourth generation of quarks is almost ruled out from the data on Higgs boson production and decay at the Large Hadron Collider, vector-like quarks are still a feasible option to extend the fermionic sector of the Standard Model. Such an extension does not suffer from any anomalies and easily passes the constraints coming from oblique electroweak parameters. We consider such minimal extensions with $SU(2)$ singlet and doublet vector-like quarks that may mix with one, or at the most two, of the Standard Model quarks. Constraints on the new mixing angles and phases are obtained from several $\Delta B = 1$ and $\Delta B = 2$ processes.