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Publication
Search for doubly charged Higgs boson production in multi-lepton final states with the ATLAS detector using proton–proton collisions at $\sqrt{s}=13\,\text {TeV}$
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Abstract(s)
A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 $\text {fb}^{-1}$ of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at the LHC. This analysis focuses on the decays $H^{\pm \pm }\rightarrow e^{\pm }e^{\pm }$ , $H^{\pm \pm }\rightarrow e^{\pm }\mu ^{\pm }$ and $H^{\pm \pm }\rightarrow \mu ^{\pm }\mu ^{\pm }$ , fitting the dilepton mass spectra in several exclusive signal regions. No significant evidence of a signal is observed and corresponding limits on the production cross-section and consequently a lower limit on $m(H^{\pm \pm })$ are derived at 95% confidence level. With $\ell ^{\pm }\ell ^{\pm }=e^{\pm }e^{\pm }/\mu ^{\pm }\mu ^{\pm }/e^{\pm }\mu ^{\pm }$ , the observed lower limit on the mass of a doubly charged Higgs boson only coupling to left-handed leptons varies from 770 to 870 GeV (850 GeV expected) for $B(H^{\pm \pm }\rightarrow \ell ^{\pm }\ell ^{\pm })=100\%$ and both the expected and observed mass limits are above 450 GeV for $B(H^{\pm \pm }\rightarrow \ell ^{\pm }\ell ^{\pm })=10\%$ and any combination of partial branching ratios.