BFKL resummation effects in gamma^* gamma^* --> rho rho
Résumé
We calculate the leading order BFKL amplitude for the exclusive diffractive process $\gamma^*_L (Q_1^2) \gamma^*_L(Q_2^2) \to \rho_L^0 \rho_L^0$ in the forward direction, which can be studied in future high energy e+e- linear colliders. The resummation effects are very large compared to the fixed-order calculation. We also estimate the next-to-leading logarithmic corrections to the amplitude by using a specific resummation of higher order effects and find a substantial growth with energy, but smaller than at the leading order.