On timelike and spacelike hard exclusive reactions
  We show to next-to-leading order accuracy in the strong coupling alpha_s how the collinear factorization properties of QCD in the generalized Bjorken regime relate exclusive amplitudes for spacelike and timelike hadronic processes. This yields simple space--to--timelike relations linking the amplitudes for electroproduction of a photon or meson to those for photo- or meso-production of a lepton pair. These relations constitute a new test of the relevance of leading twist analyzes of experimental data. 
D. Mueller, B. Pire, L. Szymanowski, J. Wagner
hep-ph hep-ex nucl-ex nucl-th