Stepping Into Electroweak Symmetry Breaking: Phase Transitions and Higgs Phenomenology

TL;DR

This paper explores a two-step electroweak phase transition in an extended Standard Model with a triplet Higgs, which could enable baryogenesis and dark matter candidates, while analyzing collider constraints.

Contribution

It introduces a novel two-step electroweak symmetry-breaking scenario with a triplet Higgs, extending the Standard Model and analyzing its phenomenological implications.

Findings

The scenario exhibits a strongly first order phase transition for baryogenesis.

The second step allows for a dark matter candidate.

Collider constraints from Higgs diphoton decay are considered.

Abstract

We study the dynamics of electroweak symmetry-breaking in an extension of the Standard Model where the Higgs sector is augmented by the addition of a real (Y = 0) isospin triplet. We show that this scenario exhibits a novel, two-step electroweak phase transition, wherein the first step provides the strongly first order transition as required for electroweak baryogenesis followed by a second step to the Standard Model Higgs phase that also admits a cold dark matter candidate. We analyze the constraints on this scenario from recent results obtained at the Large Hadron Collider for the Higgs diphoton decay channel. We argue that this two-step scenario can be generalized to extensions of the Standard Model with additional higher-dimensional scalar multiplets that may yield realistic baryogenesis dynamics.