Monophoton events with light Higgs bosons in the secluded UMSSM

Abstract

We explore the Higgs boson implications of a class of supersymmetric models, which extends the MSSM gauge group by a U(1)' symmetry, which is broken at low energy scales by vacuum expectation values of four MSSM singlet fields. These singlets also form a secluded sector, and one of them is allowed to interact with the MSSM Higgs fields directly. After the U(1)' and electroweak symmetry breaking, the low scale spectra include six CP -even and four CP-odd Higgs bosons, whose masses can lie from 80 GeV to 2-3 TeV. We find that the heavy CP-even Higgs bosons can be probed through their decays into a pair of SM gauge bosons currently up to about m(hi) similar or equal to 1.5 TeV, while their probe can be extended to about mh(i) similar or equal to 2.5 TeV in the near future. The most interesting feature of the low scale spectra in the class of secluded U(1)' models is to include two light CP -odd Higgs bosons whose masses are bounded at about 250 GeV by the current collider and DM experiments, when the LSP neutralino is mostly formed by the MSSM singlets. These light CP -odd Higgs bosons should be formed by the MSSM singlet scalars to be consistent with the current constraints. Despite their singlet nature, they can be traced through their associated production with photons. In our work, we consider their productions at the collider experiments together with photons, and we realize that these light Higgs bosons can potentially be probed during Run-3 experiments of LHC when they are lighter than about 100 GeV. We also show that Run-4 and HL-LHC experiments will be able to probe these light scalars up to about 250 GeV.