  One of the challenges of collider physics is to unambiguously associate
detector based objects with the corresponding elementary physics objects. A
particular example is the association of calorimeter-based objects such as
"jets", identified with a standard (IR-safe) jet algorithm, with the underlying
physics objects, which may be QCD-jets (arising from a scattered parton),
electrons, photons and, as discussed here, photon-jets (a group of collinear
photons). This separation is especially interesting in the context of Higgs
searches, where the signal includes both di-photon (in the Standard Model) and
di-photon-jet decays (in a variety of Beyond the Standard Model scenarios),
while QCD provides an ever-present background. Here we describe the
implementation of techniques from the rapidly evolving area of jet-substructure
studies to not only enhance the more familiar photon-QCD separation, but also
separately distinguish photon-jets, i.e., separate usual jets into three
categories: single photons, photon-jets and QCD. The efficacy of these
techniques for separation is illustrated through studies of simulated data.
