Minijets, soft gluon resummation and photon cross-sections
  We compare the high energy behaviour of hadronic photon-photon cross-sections in different models. We find that the photon-photon cross-section appears to rise faster than the purely hadronic ones (proton-proton and proton-antiproton). 
R.M. Godbole, A. Grau, G. Pancheri and Y.N. Srivastava