Search for charged Higgs bosons in e+e− collisions at $\sqrt{s}=189\mbox{--}209\ \mbox{GeV}$

Abstract

A search is made for charged Higgs bosons predicted by Two-Higgs-Doublet extensions of the Standard Model (2HDM) using electron-positron collision data collected by the OPAL experiment at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sqrt{s}=189\mbox{--}209\ \mbox{GeV}$\end{document}, corresponding to an integrated luminosity of approximately 600 pb−1. Charged Higgs bosons are assumed to be pair-produced and to decay into \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\mathrm{q} \bar{\mathrm{q}}$\end{document}, τντ or AW±. No signal is observed. Model-independent limits on the charged Higgs-boson production cross section are derived by combining these results with previous searches at lower energies. Under the assumption \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\mathrm{BR} (\mathrm{H}^{\pm} \to \tau\nu_{\tau}) + \mathrm{BR} (\mathrm{H}^{\pm} \to \mathrm{q} \bar{\mathrm{q}}) = 1$\end{document}, motivated by general 2HDM type II models, excluded areas on the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$[m_{\mathrm{H}^{\pm}} , \mathrm{BR} (\mathrm {H}^{\pm} \to \tau\nu_{\tau})]$\end{document} plane are presented and charged Higgs bosons are excluded up to a mass of 76.3 GeV at 95 % confidence level, independent of the branching ratio BR(H±→τντ). A scan of the 2HDM type I model parameter space is performed and limits on the Higgs-boson masses \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$m_{\mathrm{H}^{\pm}}$\end{document} and mA are presented for different choices of tanβ.

A 96 GeV Higgs boson in the N2HDM

“…1 The rejected parameter points are concentrated in the region tan β < 1, where the coupling of the charged Higgs to top quarks is enhanced [41]. Bounds from searches for charged Higgs bosons at LEP [51][52][53][54][55][56][57] are irrelevant for our analysis, because constrains from flavor physics observables usually exclude very light H ± kinematically in the reach of LEP. Direct searches for additional neutral Higgs bosons can exclude some of the parameter points, mainly when the heavy Higgs boson h 3 or the CP-odd Higgs boson A are rather light.…”

On lepton flavor universality in top quark decays

“…If the higher dimension operators are generated at tree level, the matching implies the presence of new EM charged particles. Existing LEP bounds [21][22][23] then require Λ 100 GeV. While this confirms the EFT treatment of the B decays as adequate, the same is not necessarily true for the top decays.…”

Heavy charged scalars from $$ c\overline{s} $$ fusion: a generic search strategy applied to a 3HDM with U(1) × U(1) family symmetry

“…Conversely, a light charged Higgs boson (m H ± m t ) that decays to τν [15,19], cs [20,21] or cb [22] has also been searched for at the LHC. Previously, at LEP, pair production of H ± was considered where H ± subsequently decays to a W ± A pair [23,24] (where A is a scalar with mass m A > 12 GeV and predominantly decays to bb pairs).…”