750 GeV diphoton resonance from singlets in an exceptional supersymmetric standard model

Abstract

Abstract: 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, (Formula presented.) and two copies of charged inert Higgsinos (Formula presented.) , (Formula presented.) 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 ZN′, D, (Formula presented.) , (Formula presented.) , (Formula presented.) 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.