a Relativistic Potential Model of Proton Scattering Spin Observables.
A model has been constructed of the interaction between protons and applied to the calculation of spin -dependent elastic scattering parameters over a range of beam momenta from 3 to 24 GeV/c. The interaction uses a one boson exchange potential, augmented by a zero-range core, and a zero-range imaginary potential to account for inelastic channels. The quark structure of the proton is taken into account by means of transition form factors modifying the meson exchange potentials. These form factors were derived from the assumption that massless quarks are bound into protons by a linear confining potential which incorporates chiral symmetry. The scattering equation was a new continuum form of the instantaneous Bethe-Salpeter Equation, which contains some of the effects of negative energy intermediate states. The model provides excellent agreement with experimental measurements of the unpolarized differential cross-section, and reproduces the qualitative features of the transverse asymmetry and spin correlation. The absorptive potential is found to dominate the real potential by two orders of magnitude at 24 GeV/c. The lowest partial waves were found to be almost completely absorbed. This suggests that perturbative quantum chromodynamics does not apply to elastic scattering at the length scales examined here, since absorptive effects prevent the quarks from approaching to appropriately small separations.
- Pub Date:
- Physics: Nuclear; Physics: Elementary Particles and High Energy