====== TTP01-28 Duality in Semi-Exclusive Processes ======
 
 
   <hidden TTP01-28  Duality in Semi-Exclusive Processes > Semi-exclusive processes like $\gamma p \to \pi^+ Y$ are closely analogous to
 DIS, $ep \to eX$, in the limit where the momentum transfer $|t|$ to the pion
 and the mass of the inclusive system $Y$ are large but still much smaller
 than the total CM energy. We apply Bloom-Gilman duality
 to this semi-exclusive process. The energy dependence of the $\gamma p \to
 \pi^+ n$ cross section given by semi-local duality agrees with data for
 moderate values of $|t|$, but its normalization is underestimated by about
 two orders of magnitude. This indicates that rather high momentum transfers
 are required for the validity of PQCD in the hard subprocess $\gamma u \to
 \pi^+ d$. In the case of Compton scattering $\gamma p \to \gamma p$ the
 analogous discrepancy is about one order of magnitude. In electroproduction
 the virtuality of the incoming photon can be used to directly measure the
 hardness of the subprocess.
 </hidden>
|**Patrik Eden, Paul Hoyer and Alexander Khodjamirian**  | 
|**  JHEP  0110:040 1-7 2001  **  |
| {{preprints:2001:ttp01-28.pdf|PDF}} {{preprints:2001:ttp01-28.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/0110297|arXiv]]   |
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