Testing Effective Yukawa Couplings in Higgs Searches at the Tevatron and LHC

TL;DR

This paper investigates a scenario where fermion masses originate from a higher energy scale, leading to modified Higgs decay patterns and proposing new search strategies at colliders like the LHC.

Contribution

It introduces a framework where Yukawa couplings are radiatively generated at low energies, altering Higgs decay modes and production mechanisms for collider searches.

Findings

Enhanced Higgs decays into photons and weak bosons for light Higgs.

Possible large decay rate into bar{b} comparable to gamma gamma channel.

Vector-boson fusion becomes the dominant Higgs production at the LHC.

Abstract

We explore the possibility that, while the Higgs mechanism provides masses to the weak-gauge bosons at the electroweak scale as in the standard model, fermion masses are generated by an unknown mechanism at a higher energy scale. At low energies, the standard model can then be regarded as an effective field theory, where fermion masses explicitly break the electroweak SU(2)_L \times U(1)_Y gauge symmetry. If \Lambda is the renormalization scale where the renormalized Yukawa couplings vanish, then at energies lower than \Lambda, effective Yukawa couplings will be radiatively induced by nonzero fermion masses. In this scenario, Higgs-boson decays into photons and weak gauge-bosons pairs are in general quite enhanced for a light Higgs. However, depending on \Lambda, a substantial decay rate into b \bar{b} can arise, that can be of the same order as, or larger than, the enhanced H\to gamma gamma rate. A new framework for Higgs searches at hadron colliders is outlined, vector-boson fusion becoming the dominant production mechanism at the CERN LHC, with an important role also played by the WH/ZH associated production. A detailed analysis of the Higgs branching fractions and their implications in Higgs searches is provided, versus the energy scale \Lambda.