Custodial Symmetry Breaking and Higgs Signatures at the LHC

TL;DR

This paper explores a simple model predicting a modified $ ho$ parameter and new Higgs bosons, analyzing their decay properties and potential LHC signatures, including a possible diphoton signal at low masses.

Contribution

It introduces a minimal model with a tree-level $ ho$ parameter modification and detailed predictions for new Higgs bosons' decay modes and collider signatures.

Findings

Masses around 200 GeV are excluded in some scenarios.

New bosons can have masses near the electroweak scale without conflicting with current data.

Fermiophobic neutral Higgs could produce a diphoton signal at low masses.

Abstract

We discuss the simplest model that predicts a tree level modification of the $\rho$ parameter from a shift in the $W$-mass without changing the prediction for the $Z$ mass. This model predicts a new neutral Higgs and two charged Higgses, with very similar masses and suppressed couplings to the Standard Model fermions. We discuss the decay properties of these new scalar bosons, and the main signatures at the Large Hadron Collider. Comparing these signatures for the first time to the latest measurements, we show that while masses around 200 GeV are excluded for some scenarios, over a wide range of model parameter space the new bosons can have a mass close to the electroweak scale without violating existing limits from experimental searches or destroying the agreement with measurements. We investigate the scenario where the new neutral Higgs is fermiophobic and has a large branching ratio into $W$ gauge bosons and/or photons, and show that this could lead to a signal in the diphoton mass spectrum at low Higgs masses. We discuss the different signatures that can motivate new measurements and searches at the Large Hadron Collider.