750 GeV Diphoton Resonance from Singlets in an Exceptional Supersymmetric Standard Model

Original · EN

The 750-760 GeV diphoton resonance may be identified as one or two scalars and/or one or two pseudoscalars contained in the two singlet superfields S₁,₂ arising from the three 27-dimensional representations of E₆. The three 27s also contain three copies of colour-triplet charge ∓ 1/3 vector-like fermions D,D and two copies of charged inert Higgsinos H⁺,H⁻ to which the singlets S₁,₂ may couple. We propose a variant of the E₆SSM where the third singlet S₃ breaks a gauged U(1)ₙ above the TeV scale, predicting Z'ₙ, D,D, H⁺,H⁻ at LHC Run 2, leaving the two lighter singlets S₁,₂ with masses around 750 GeV. We calculate the branching ratios and cross-sections for the two scalar and two pseudoscalar states associated with the S₁,₂ singlets, including possible degeneracies and maximal mixing, subject to the constraint that their couplings remain perturbative up to the unification scale.