Results of Beyond-the-Standard Model 2HDM Higgs Searches using the ATLAS detector in Run-I

Abstract

One of the most alluring models used to probe Beyond the Standard Model physics in run-I at ATLAS stems from a simple extension of the Higgs sector. Models where the Higgs sector is assumed to have two Higgs doublets, known as two-Higgs-Doublet-Models (2HDMs), give rise to five Higgs bosons: two neutral CP-even (h,H) bosons, two charged (H±) bosons, and one neutral CP-odd (A) boson. Direct searches for the additional Higgs bosons became an ever more promising prospect after the Higgs boson discovery, and various such searches have already been conducted in Run-I ATLAS data. The most recent 2HDM search is for the A boson in the sensitive Zh decay, where h is assumed to be the LHC discovered Higgs boson, within the mass range of 220 — 1000 GeV. In such a search, upper limits on the cross section times branching ratio of the A boson decaying to Zh are set for various 2HDM scenarios. Where no excess is observed, exclusion limits are set on ranges of the 2HDM phase-space. In this note the search for A → Zh → ℓℓττ with fully hadronic tau decay is presented in detail, along with summaries from two of the most recent 2HDM searches in ATLAS.