Sudakov effects inpp¯annihilation

We compute the amplitudes for $p\overline{p}\to \gamma \gamma$ and $p\overline{p}\to l\overline{l}$, taking into account the Sudakov suppression resulting from radiation by isolated partons. Results for the two-photon annihilation process and form factor are presented for several candidate proton distribution amplitudes. Results are also presented for the ratio $\frac{\sigma (p\overline{p}\to \gamma \gamma )}{\sigma (p\overline{p}\to e^{+}{e}^{-})}$, which is free of experimental and theoretical normalization uncertainties. Prospects for using these results to constrain the nucleon distribution amplitude are discussed.