Abstract
We show that an endpoint overlap model can explain the scaling laws observed in exclusive hadronic reactions at large momentum transfer. The model assumes one of the valence quarks carries most of the hadron momentum. Hadron form factors and fixed angle scattering are related directly to the quark wave function, which can be directly extracted from experimental data. A universal linear endpoint behavior explains the proton electromagnetic form factor, proton-proton fixed angle scattering, and the t-dependence of proton-proton scattering at large s>>t. Endpoint constituent counting rules relate the number of quarks in a hadron to the power-law behavior. All proton reactions surveyed are consistent with three quarks participating. The model is applicable at laboratory energies and does not need assumptions of asymptotically-high energy regime. A rich phenomenology of lepton-hadron scattering and hadron-hadron scattering processes is found in remarkably simple relationships between diverse processes.
Highlights
F1(Q2) agrees well with a decreasing power of Q2 for Q2 5 GeV2 [9]
The independent scattering (I S) model gets its power law partly from the phase space of fast quarks with x ∼ 1/3 to overlap with the wave function in the final state
We have shown that the endpoint-overlap model stands as a comprehensive theory of hadronic reactions at large momentum transfer
Summary
The experimental study of differential cross sections of hard exclusive hadronic reactions at high energy reveals a remarkable pattern: They are described by power laws [1,2,3]. A model explanation exists [4,5,6,7], yet it is not satisfactory [8] at the energies of experimental measurements. We are driven to find a consistent explanation of experimental regularities by re-examining all the facts from a fresh point of view. It is remarkable that with pp → pp fixed-angle cross section d a decreasing power of Q2 ∼ s [10], σ/dt ag√rees well where s is the center of mass energy. There is much to be learned and much that is new when the model is objectively explored
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