Isolated photons in perturbative QCD
  I present a definition of the cross section for the production of an isolated photon plus $n$ jets which only depends upon direct photon production, and it is independent of the parton-to-photon fragmentation contribution. This prescription, based on a modified cone approach which implements the isolation condition in a smooth way, treats in the same way quarks and gluons and can be directly applied to experimental data in hadron-hadron, photon-hadron and $\epem$ collisions. The case of several, isolated photons in the final state can also be dealt with in the very same way. 
S. Frixione (ETH)