Abstract
The search for heavy Higgs bosons at the LHC represents an intense experimental program, carried out by the ATLAS and CMS collaborations, which includes the hunt for invisible Higgs decays and dark matter candidates. No significant deviations from the SM backgrounds have been observed in any of these searches, imposing significant constraints on the parameter space of different new physics models with an extended Higgs sector. Here we discuss an alternative search strategy for heavy Higgs bosons decaying invisibly at the LHC, focusing on the pair production of a heavy scalar H together with a pseudoscalar A, through the production mode qq¯→Z⁎→HA. We identify as the most promising signal the final state made up of 4b+ETmiss, coming from the heavy scalar decay mode H→hh→bb¯bb¯, with h being the discovered SM-like Higgs boson with mh=125GeV, together with the invisible channel of the pseudoscalar. We work within the context of simplified MSSM scenarios that contain quite heavy sfermions of most types with O(10)TeV masses, while the stops are heavy enough to reproduce the 125 GeV mass for the lightest SM-like Higgs boson. By contrast, the gauginos/higgsinos and the heavy MSSM Higgs bosons have masses near the EW scale. Our search strategies, for a LHC center-of-mass energy of s=14TeV, allow us to obtain statistical significances of the signal over the SM backgrounds with values up to ∼1.6σ and ∼3σ, for total integrated luminosities of 300fb−1 and 1000fb−1, respectively.
Highlights
The discovery at the LHC of a SM-like Higgs boson [1,2], with the most recent measurement of its mass set at mhSM = 125.09 ± 0.21 ±0.11 GeV [3], has been a major confirmation of the standard model of particle physics (SM)
The lightest Higgs boson h is usually identified with the discovered SM-like Higgs boson of 125 GeV and there is an intense experimental program, performed by the ATLAS and CMS collaborations, in order to search for the remaining heavy Higgs bosons at the LHC, that depends on the different Higgs decay channels considered
This same final state has been recently analyzed by CMS [100] within the context of gauge-mediated SUSY breaking, considering the electroweak production of two higgsinos that decay into the lightest Higgs boson h and the lightest supersymmetric particle (LSP) goldstino G
Summary
Without the vector boson fusion and bremsstrahlung modes, which are absent for the pseudoscalar, the other possible production mechanisms are the associated with a light Higgs and with a pair of quarks The former is dynamically suppressed within the MSSM whereas the latter has a cross section at the edge of accessibility at HL-LHC. This low-tanβ regime [78], recently noticed in [76,77] and highlighted in [54–58,79,80], gives rise to a rich Higgs phenomenology since the decay rates of the heavy Higgs bosons are not dominated by the decay channels into bottomquark and τ -lepton pairs, as occurs for moderate and large values of tan β This situation opens the possibility of heavy Higgs boson searches through interesting channels, as H → W +W −, H → ZZ, H → hh, A → hZ, the decay modes into top-quark pairs H, A → tt, and the invisible decays H, A → χχ.
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