Constraints on Mass Spectrum of Fourth Generation Fermions and Higgs Bosons

TL;DR

This paper reexamines the mass constraints on fourth generation fermions and Higgs bosons in the SM4 and THDM, revealing new allowed mass spectra and phenomenological possibilities.

Contribution

It provides updated constraints on the mass spectrum of fourth generation particles and Higgs bosons in two models, highlighting the range of phenomenologically viable scenarios.

Findings

Higgs mass in SM4 should exceed the fourth generation up-type quark mass

In THDM, the light CP even Higgs can be lighter than the fourth generation quarks

Various mass spectra of fourth generation fermions and Higgs bosons are permitted

Abstract

We reanalyze constraints on the mass spectrum of the chiral fourth generation fermions and the Higgs bosons for the standard model (SM4) and the two Higgs doublet model (THDM). We find that the Higgs mass in the SM4 should be larger than roughly the fourth generation up-type quark mass, while the light CP even Higgs mass in the THDM can be smaller. Various mass spectra of the fourth generation fermions and the Higgs bosons are allowed. The phenomenology of the fourth generation models is still rich.