Search for doubly charged Higgs boson production in multi-lepton final states using 139 fb-1 of proton-proton collisions at SQUARE ROOTs = 13 TeV with the ATLAS detector
Abstract
A search for pair production of doubly charged
Higgs bosons (H+-+-), each decaying into a pair of prompt, isolated, and 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 an integrated luminosity of 139 fb-1 recorded by the ATLAS detector during Run 2 of the Large Hadron
Collider (LHC). This analysis focuses on same-charge leptonic decays, H+-+- RIGHTWARDS ARROW
+-
+- where ,
= e,μ, τ, in two-, three-, and four-lepton channels, but only considers final states which include electrons or muons. No evidence of a signal is observed. Corresponding upper limits on the production cross-section of a doubly charged Higgs boson are derived, as a function of its mass m(H+-+-
), at 95% confidence level. Assuming that the branching ratios to each of the possible leptonic final states are equal, B(H+-+- RIGHTWARDS ARROW e+-e+-
) =
B(H+-+- RIGHTWARDS ARROW e+-
μ
+-
) = B(H+-+- RIGHTWARDS ARROW μ
+-
μ
+-
) = B(H+-+- RIGHTWARDS ARROW e+-
τ
+-
) = B(H+-+- RIGHTWARDS ARROW μ
+-
τ
+-
) = B(H+-+- RIGHTWARDS ARROW τ
+-
τ
+-
) = 1/6, the observed (expected) lower limit on the mass of a doubly charged Higgs boson is 1080GeV(1065 GeV) within the leftright symmetric type-II seesaw model, which is the strongest limit to date produced by the ATLAS Collaboration. Additionally, this paper provides the first direct test of the Zee-
Babu neutrino mass model at the LHC, yielding an observed
(expected) lower limit of m(H+-+-
) = 900 GeV (880 GeV).