now leading to an enhanced role for the harder components of the $\gamma^*$-wavefunction and a resulting stronger energy dependence of the cross section.

Rapidity gaps between jets at Fermilab and HERA
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Suppose one measures two jets having comparable but opposite transverse momentum along with the requirement that there be a rapidity gap between two jets. One might hope that this would be a good process to measure the hard (BFKL) pomeron as illustated in Fig.6\[36\]. There are, however, at least two worries with using this process to measure the hard pomeron. (i) The pomeron contribution to the hard quark-antiquark scattering is\[37\].

$${d^{\sigma}\over dt} = (\alpha C_F)^4\  {\pi^3\over 4 t^2} {exp[2(\alpha_P-1)
\Delta Y]\over [{7\over 2} \alpha N_c\zeta(3) \Delta Y]^3}\eqno(4.1)$$

with $\Delta Y$ the rapidity between the two jets. Here $\alpha_P-1=
{4\alpha N_c\over \pi} \ell n 2$ is the BFKL pomeron intercept. The presence of the factor $(\Delta Y)^3$ in the denominator in (4.1) strongly reduces the effective growth of the cross section with $\Delta Y$ making the emergence of the hard pomeron more difficult at moderate values of $\Delta Y.$ (ii) Perhaps more serious yet is the fact that the cross section for producing two jets with a gap between 