Cracking Down on Fake Photons - A Case of 750 GeV Diphoton Resonance -
  Among various models to explain the $750$ GeV diphoton resonance hinted at the LHC Run 2, a class of models where the resonance decays not into a pair of photons but into a pair of photon-jets is gathering definite attention. In this paper, we study how well we can distinguish the di-photon-jet resonance from the diphoton resonance by examining detector responses to the photon-jets. We find that the sum of $p_T$ of the first $e^+e^-$ pair from the photon conversion provides strong discrimination power. We also discuss determination of the lifetime of the light intermediate particle by measuring the photon conversion points. 
Hajime Fukuda, Masahiro Ibe, Osamu Jinnouchi and Mihoko Nojiri
hep-ph hep-ex