From static potentials to high-energy scattering

We develop a loop-loop correlation model for a unified description of static color dipole potentials, confining QCD strings, and hadronic high-energy reactions with special emphasis on saturation effects manifesting S-matrix unitarity at ultra-high energies. The model combines perturbative gluon exchange with the non-perturbative stochastic vacuum model which describes color confinement via flux-tube formation of color fields. We compute the chromo-field distributions of static color dipoles in various SU(N_c) representations and find Casimir scaling in agreement with recent lattice QCD results. We investigate the energy stored in the confining string and use low-energy theorems to show consistency with the static quark-antiquark potential. We generalize Meggiolaro's analytic continuation from parton-parton to dipole-dipole scattering and obtain a Euclidean approach to high-energy scattering that allows us in principle to calculate S-matrix elements in lattice QCD. In this approach we compute high-energy dipole-dipole scattering with the Euclidean loop-loop correlation model. Together with a universal energy dependence and reaction-specific wave functions, the result forms the basis for a unified description of proton-proton, pion-proton, kaon-proton, photon-proton, and photon-photon reactions in good agreement with experimental data for cross sections, slope parameters, and structure functions. The obtained impact parameter profiles for proton-proton and longitudinal photon-proton reactions and the impact parameter dependent gluon distribution of the proton xG(x,Q^2,b) show saturation at ultra-high energies in accordance with unitarity constraints.

Note:

Doctoral Thesis (Advisor: H.G.Dosch, Bogdan Povh)

thesis
gauge field theory: SU(N)
color: dipole
potential: static
correlation function
string model: confinement
parton: scattering
dipole: scattering
approximation: Euclidean
S-matrix: unitarity

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