More Higgses at the LHC and the Electroweak Phase Transition

Abstract

A cosmological first order electroweak phase transition could explain the origin of the cosmic matter-antimatter asymmetry. While it does not occur in the Standard Model, it becomes possible in the presence of a second Higgs doublet. In this context, we obtain the properties of the new scalars $H_0$, $A_0$ and $H^{\pm }$ leading to such a phase transition, showing that its key LHC signature would be the decay $A_0\to H_{0}Z$, and we analyze the promising LHC search prospects for this decay in the $\ell \ell b\bar{b}$ and $\ell \ell W^{+}{W}^{-}$ final states. Finally, we comment on the impact of the $A_0\to H_{0}Z$ decay on current LHC searches for $A_0$ decaying into SM particles.

Comments: 4 pages, 3 figures, talk presented at the XXVIIth Rencontres de Blois, France, 31 May - 5 June 2015