Search for a CP-odd Higgs boson decaying to Zh in pp collisions at √s=8 TeV with the ATLAS detector

Search for a CP-odd Higgs boson decaying to Zh in pp collisions at √ s = 8 TeV with the ATLAS detector .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t A search for a heavy, CP-odd Higgs boson, A, decaying into a Z boson and a 125 GeV Higgs boson, h, with the ATLAS detector at the LHC is presented. The search uses proton–proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb −1. Decays of CP-even h bosons to τ τ or bb pairs with the Z boson decaying to electron or muon pairs are considered, as well as h → bb decays with the Z boson decaying to neutrinos. No evidence for the production of an A boson in these channels is found and the 95% confidence level upper limits derived for σ (gg → A) × BR(A → Zh) × BR(h → f ¯ f) are 0.098–0.013 pb for f = τ and 0.57–0.014 pb for f = b in a range of m A = 220–1000 GeV. The results are combined and interpreted in the context of two-Higgs-doublet models. After the discovery of a Higgs boson at the LHC in 2012 [1,2], one of the most important remaining questions is whether the newly discovered particle is part of an extended scalar sector. A CP-odd Higgs boson, A, appears in many models with an extended scalar sector, e.g. in the case of the two-Higgs-doublet model (2HDM) [3]. The addition of a second Higgs doublet leads to five Higgs bosons after the electroweak symmetry breaking. The phenomenol-ogy of such a model is very rich and depends on the vacuum expectation values of the Higgs doublets, the CP properties of the Higgs potential and the values of its parameters and the Yukawa couplings of the Higgs doublets with the fermions. In general, it is possible to accommodate in the model a Higgs boson compatible to the one discovered at the LHC. In the case where the Higgs potential of the 2HDM is CP-conserving, the Higgs bosons after electroweak symmetry breaking are two CP-even (h and H), one CP-odd (A) and two charged (H ±) Higgs bosons. Many theories beyond the Standard Model (SM) include a second Higgs doublet, such as the minimal supersymmetric SM (MSSM) [4–8], axion models …