Extra Higgses at LHC: the EW Road to Baryogenesis

TL;DR

This paper explores how a second Higgs doublet could enable a first order electroweak phase transition, providing a potential explanation for matter-antimatter asymmetry and predicting observable signatures at the LHC.

Contribution

It identifies the properties of new scalars that facilitate the phase transition and analyzes their detectable decay signatures at the LHC, advancing beyond Standard Model predictions.

Findings

Decay $A_0 ightarrow H_0 Z$ is a key signature for the phase transition.

LHC searches in $ ext{ll}bar{b}$ and $ ext{ll}W^{+}W^{-}$ channels are promising.

Early 14 TeV runs could observe these signatures.

Abstract

A cosmological first order electroweak phase transition could explain the origin of the matter-antimatter asymmetry in the Universe. Such a phase transition does not occur in the Standard Model, while it becomes possible with the existence of a second Higgs doublet in Nature. We obtain the properties of the new scalars $H_0$, $A_0$ and $H^{\pm}$ that lead to such a phase transition, showing that its characteristic signature at LHC would be the observation of the decay $A_0 \rightarrow H_0 Z$. We analyze the LHC search prospects for this decay in the $\ell \ell b\bar{b}$ and $\ell \ell W^{+} W^{-}$ final states, showing that either one is promising at the early stages of the 14 TeV run.