Search for additional heavy neutral Higgs and gauge bosons in the ditau final state produced in 36 fb−1 of pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV with the ATLAS detector

Abstract

Search for additional heavy neutral Higgs and gauge bosons in the ditau final state produced in 36 fb −1 of pp collisions at √ s = 13 TeV with the ATLAS detectorThe ATLAS collaboration E-mail: atlas.publications@cern.ch Abstract: A search for heavy neutral Higgs bosons and Z bosons is performed using a data sample corresponding to an integrated luminosity of 36.1 fb −1 from proton-proton collisions at √ s = 13 TeV recorded by the ATLAS detector at the LHC during 2015 and 2016. The heavy resonance is assumed to decay to τ + τ − with at least one tau lepton decaying to final states with hadrons and a neutrino. The search is performed in the mass range of 0.2-2.25 TeV for Higgs bosons and 0.2-4.0 TeV for Z bosons. The data are in good agreement with the background predicted by the Standard Model. The results are interpreted in benchmark scenarios. In the context of the hMSSM scenario, the data exclude tan β > 1.0 for m A = 0.25 TeV and tan β > 42 for m A = 1.5 TeV at the 95% confidence level. For the Sequential Standard Model, Z SSM with m Z < 2.42 TeV is excluded at 95% confidence level, while Z NU with m Z < 2.25 TeV is excluded for the non-universal G(221) model that exhibits enhanced couplings to third-generation fermions. 6 Background estimation 10 6.1 Jet background estimate in the τ had τ had channel 10 6.1. The ATLAS collaboration 37-1 - JHEP01(2018)0551 IntroductionThe discovery of a scalar particle [1, 2] at the Large Hadron Collider (LHC) [3] has provided important insight into the mechanism of electroweak symmetry breaking. Experimental studies of the new particle [4][5][6][7][8] demonstrate consistency with the Standard Model (SM) Higgs boson [9][10][11][12][13][14]. However, it remains possible that the discovered particle is part of an extended scalar sector, a scenario that is predicted by a number of theoretical arguments [15,16]. The Minimal Supersymmetric Standard Model (MSSM) [15,17,18] is the simplest extension of the SM that includes supersymmetry. The MSSM requires two Higgs doublets of opposite hypercharge. Assuming that CP symmetry is conserved, this results in one CPodd (A) and two CP-even (h, H) neutral Higgs bosons and two charged Higgs bosons (H ± ). At tree level, the properties of the Higgs sector in the MSSM depend on only two non-SM parameters, which can be chosen to be the mass of the CP-odd Higgs boson, m A , and the ratio of the vacuum expectation values of the two Higgs doublets, tan β. Beyond tree level, a number of additional parameters affect the Higgs sector, the choice of which defines various MSSM benchmark scenarios. In the m mod+ h scenario [19], the top-squark mixing parameter is chosen such that the mass of the lightest CP-even Higgs boson, m h , is close to the measured mass of the Higgs boson that was discovered at the LHC. A different approach is employed in the hMSSM scenario [20,21] in which the measured value of m h can be used, with certain assumptions, to predict the remaining masses and couplings of the MSSM Higgs bosons without explicit reference to the sof...

Wrong sign bottom Yukawa coupling in low energy supersymmetry

“…If we want t β c β−α to be as large as 2, it is clear that we need the third term in the square bracket to be quite large. Unfortunately, this will lead to an unacceptably large value of t β , which pushes the Yukawa coupling to third generation down-type fermions to large values that are restricted by heavy Higgs searches [17,18]. In order to see that, let us recall the fact that stability of the Higgs potential demands that jA t j and jμj should both be smaller than 3M S [31].…”

“…More specifically, for m H ≈ 250 GeV, one requires values of t β ≈ 30, while for m H ≈ 500 GeV, t β ≈ 120. These values of m H and t β are excluded by heavy Higgs searches at the LHC [17,18]. One could avoid these constraints for larger values of the heavy Higgs mass, larger than 1 TeV.…”

“…This region of parameter space, however, is strongly restricted by searches for Higgs bosons decaying into τ-lepton pairs [17,18], which makes the realization of this scenario difficult. As we shall show in this article, the scenario is more easily realized in the NMSSM, although the necessary values of the coupling λ of the singlet to the doublet Higgs superfields are larger than the ones leading to perturbative consistency of the theory up to the GUT scale.…”

Signal to background interference in pp→tH−→tW−bArhrib1, Benbrik2, Moretti3 et al. 2018Phys. Rev. D5020View full textAdd to dashboardCite

“…In this analysis, we first consider a 2HDM type II/flipped where the pseudoscalar couplings to down-type fermions are proportional to tan β so that, for a large values of it, the width of the pseudoscalar can be made significantly large. Taking into account the latest searches on pp → Φ → τ þ τ − [40], Φ being any heavy spin-0 object, very large values of tan β are disallowed. In Table III, we present our input parameters for the type II and flipped models for five chosen BPs.…”

Probing SUSY effects in K0 S → μ+μ−

“…1.0004 ± 0.0095 [37] ∆C 7 −0.02 ± 0.02 [41] tan β:M A plane ATLAS limits for hMSSM scenario [42] LSP Lightest neutralino value over the SM prediction with their uncertainties. Due to the poor theoretical knowledge of ∆M K , we assign a 100% theoretical uncertainty; thus, the constraint imposed on this observable penalizes only O(1) effects.…”