Echoes of the Electroweak Phase Transition: Discovering a Second Higgs Doublet through ${A}_{0}\ensuremath{\rightarrow}Z{H}_{0}$

Echoes of the Electroweak Phase Transition: Discovering a Second Higgs Doublet through $A_{0} \to Z H_{0}$

G. C. Dorsch, S. J. Huber, K. Mimasu, and J. M. No

Phys. Rev. Lett. 113, 211802 – Published 20 November 2014

Abstract

The existence of a second Higgs doublet in nature could lead to a cosmological first-order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We obtain the spectrum and properties of the new scalars $H_{0}$ , $A_{0}$ , and $H^{\pm}$ that signal such a phase transition and show that the observation of the decay $A_{0} \to Z H_{0}$ at LHC would be a “smoking gun” signature of these scenarios. We analyze the LHC search prospects for this decay in the $ℓ ℓ b \bar{b}$ and $ℓ ℓ W^{+} W^{-}$ final states, arguing that current data may be sensitive to this signature in the former channel as well as there being great potential for a discovery in either channel at the very early stages of the 14 TeV run.