Subprocess Size in Hard Exclusive Scattering
نویسندگان
چکیده
The interaction region of hard exclusive hadron scattering can have a large transverse size due to endpoint contributions, where one parton carries most of the hadron momentum. The endpoint region is enhanced and can dominate in processes involving multiple scattering and quark helicity flip. The endpoint Fock states have perturbatively short lifetimes, hence are not Sudakov suppressed and scatter softly in the target. Endpoint contributions can explain the apparent absence of color transparency in fixed angle exclusive scattering and the dimensional scaling of transverse ρ photoproduction at high momentum transfer, which requires quark helicity flip.
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