Experimental considerations motivated by the diphoton excess at the LHC

Abstract

Abstract: We consider the immediate or near-term experimental opportunities offered by some scenarios that could explain the new diphoton excess at the LHC. If the excess is due to a new particle Xs at 750 GeV, additional new particles are required, providing further signals. If connected with naturalness, the Xs may be produced in top partner decays. Then a t′ t¯ ′ signal, with t′ → tXs and Xs → gg dominantly, might be discovered by reinterpreting 13 TeV SUSY searches in multijet events with low MET and/or a lepton. If Xs is a bound state of quirks, the signal events may be accompanied by an unusual number of soft tracks or soft jets. Other resonances including dilepton and photon+jet as well as dijet may lie at or above this mass, and signatures of hidden glueballs might also be observable. If the “photons” in the excess are actually long-lived particles decaying to photon pairs or to electron pairs, there are opportunities for detecting overlapping photons and/or unusual patterns of apparent photon-conversions in either Xs or 125 GeV Higgs decays. There is also the possibility of events with a hard “photon” recoiling against a narrow isolated HCAL-only “jet”, which, after the jet’s energy is corrected for its electromagnetic origin, would show a peak at 750 GeV.