Vectorlike $W^\pm$-boson coupling at TeV and third family fermion masses

TL;DR

This paper investigates how four-fermion operators influence the W boson coupling and fermion masses in the third family, suggesting a vectorlike W coupling at TeV energies and exploring collider implications.

Contribution

It introduces a model where four-fermion operators lead to a vectorlike W boson coupling at TeV scale and explains the mass hierarchy of third family fermions.

Findings

Top-quark mass arises from condensate-induced symmetry breaking.

W boson coupling becomes approximately vectorlike at TeV energies.

Fermion masses depend on top-quark properties and interactions.

Abstract

In the third fermion family and gauge symmetry of the Standard Model, we study the quark-quark, lepton-lepton and quark-lepton four-fermion operators in an effective theory at high energies. These operators have nontrivial contributions to the Schwinger-Dyson equations for fermion self-energy functions and the $W^\pm$-boson coupling vertex. As a result, the top-quark mass is generated via the spontaneous symmetry breaking of $\langle\bar t t \rangle$-condensate and the $W^\pm$-boson coupling becomes approximately vectorlike at TeV scale. The bottom-quark, tau-lepton and tau-neutrino masses are generated via the explicit symmetry breaking of $W^\pm$-contributions and quark-lepton interactions. Their masses and Yukawa couplings are functions of the top-quark mass and Yukawa coupling. We qualitatively show the hierarchy of fermion masses and Yukawa couplings of the third fermion family. We also discuss the possible collider signatures due to the vectorlike (parity-restoration) feature of $W^\pm$-boson coupling at high energies.