Abstract
In U(1) extensions of the Minimal Supersymmetric extension of the Standard Model there is a simple mechanism that leads to a heavy Z' boson with a mass which is substantially larger than the supersymmetry breaking scale. This mechanism may also result in a pseudoscalar state that is light enough for decays of the 125 GeV Standard Model-like Higgs boson into a pair of such pseudoscalars to be kinematically allowed. We study these decays within E6 inspired supersymmetric models with an exact custodial symmetry that forbids tree-level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. We argue that the branching ratio of the lightest Higgs boson decays into a pair of the light pseudoscalar states may not be negligibly small.
Highlights
The simplest renormalisable superpotential of the SUSY model of the type discussed above can be written as WS = σφSS
In U(1) extensions of the Minimal Supersymmetric extension of the Standard Model there is a simple mechanism that leads to a heavy Z boson with a mass which is substantially larger than the supersymmetry breaking scale
In this paper we considered the non-standard decays of the SM-like Higgs state within U(1) extensions of the MSSM in which the extra U(1) gauge symmetry is broken by two VEVs of the SM singlet fields S and S with opposite U(1) charges
Summary
We briefly review the E6 inspired SUSY models with exact custodial Z2H symmetry [15], which we use to demonstrate how light pseudoscalar states can appear in SUSY models with an extra U(1) gauge symmetry. This is possible because matter parity is a discrete subgroup of U(1)ψ and U(1)χ With such a breakdown into U(1)N × Z2M the right-handed neutrino mass can be generated without breaking the remaining gauge symmetry and all exotic states which originate from the 27i representations of E6 as well as ordinary quark and lepton states survive down to low energies. On the other hand if the lightest exotic particles have masses below 5 GeV their couplings to the SM-like Higgs state are small so that problems with non-standard Higgs decays can be avoided As their couplings to the gauge bosons, quarks and leptons are very small this results in a cold dark matter density that is much larger than its measured value because the corresponding annihilation cross section tends to be small. In this case the mass of the second lightest CP-even Higgs state is set by the Z boson mass, while the heaviest CP-even, CP-odd and charged states are almost degenerate and lie beyond the multi-TeV range
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