Two Higgs doublets with 4th generation fermions - models for TeV-scale compositeness

TL;DR

This paper develops two Higgs doublet models incorporating a 4th fermion generation, aiming to explain electroweak symmetry breaking via fermion condensates, with implications for collider phenomenology and experimental constraints.

Contribution

It introduces a novel two Higgs doublet framework with differentiated couplings to 4th generation fermions, linking dynamical symmetry breaking to collider signatures.

Findings

Models can fit low energy phenomenology and electroweak data.

Distinct collider signatures for 4th generation quarks and leptons.

Revised strategies needed for detecting t' and b' at colliders.

Abstract

We construct a class of two Higgs doublets models with a 4th sequential generation of fermions that may effectively accommodate the low energy characteristics and phenomenology of a dynamical electroweak symmetry breaking scenario which is triggered by the condensates of the 4th family fermions. In particular, we single out the heavy quarks by coupling the "heavier" Higgs doublet (\Phi_h) which possesses a much larger VEV only to them while the "lighter" doublet (\Phi_l) couples only to the light fermions. We study the constraints on these models from precision electroweak data as well as from flavor data. We also discuss some distinct new features that have direct consequences on the production and decays of the 4th family quarks and leptons in high energy colliders; in particular the conventional search strategies for t' and b' may need to be significantly revised.