is much larger at HERA as is natural for a point-like $\gamma^*.$ It would be interesting to have a HERA analysis similar to that of  DØ  to see if the energy dependence of the gap fraction is weaker, closer to x-independent, than at Fermilab. With respect to the DØdata the energy dependence of the gap fraction may be reflecting exactly the same phenomenon as observed in the energy dependence of the single diffraction cross section discussed in Sec.2.2. While the inclusive two-jet cross section increases at higher energies, because of the growth in the parton densities, the energy dependence of the gap cross section is likely to be much weaker because of the increasing blackness of central proton-antiproton collisions as already seen in the single diffractive cross section.

BFKL searches
=============

The hard (BFKL) pomeron or, equivalently, BFKL evolution shows up simply only in single transverse momentum hard scale processes. Thus in hadron-hadron collisions or in deep inelastic scattering where a soft scale, the size of the hadron (proton), is present a special class of events must be taken in order to isolate BFKL dynamics. Since this is generally very difficult to do experimentally it is perhaps useful to remind 