Diphoton resonance and new physics at 1 TeV

The diphoton excess with invariant mass ~750 GeV observed at the 13 TeV LHC run is studied in the extension of the Standard Model with an extra scalar S which decays can be responsible for the excess. Two scenarios of S production are considered: gluon fusion through a loop of heavy isosinglet quark(s) and photon fusion through a loop of heavy isosinglet leptons.