$\gamma^* \gamma^*$ Scattering via Secondary Reggeon Exchange in QCD
  We summarize the results on the high energy behavior of quark-antiquark exchange in $\gamma^* \gamma^*$ elastic scattering. The ladder diagrams, summed in the double logarithmic approximation, provide a perturbative QCD model for secondary reggeon exchange. 
Jochen Bartels and Michael Lublinsky