Hochenergiestreuung im Nichtperturbativen Vakuum der Quantenchromodynamik [High-energy scattering in the nonperturbative vacuum of Quantum Chromodynamics]

Abstract

We consider scattering in nonperturbative Quantum Chromodynamics (QCD) for large invariant centre of mass energy $\surd s$. Our analysis is based upon the Stochastic Vacuum Model~(SVM) of Dosch and Simonov and on the nonperturbative $s \to \infty$-asymptotic formula of Nachtmann for the scattering of two Wegner Wilson loops. We argue, that its validity can be expanded to large but finite values of~$s$ by {\sl not} substituting the initial near light-like loops for their exact light-like limits. Thus, the $T$-amplitude depends on $s$ beyond the kinematical factor. This $s$-dependence is explicitly calculated. We conclude performing the analytical continuation to Euclidean spacetime and in that way make accessible high-energy scattering to Euclidean theories such as QCD lattice gauge theory. Based upon the $s \to \infty$-asymptotic formula, we further calculate exclusive photo- and leptoproduction of a vectormeson at the proton: $\ga^{(*)}p \to V p$}, -- for $V \equiv \rho(770), \omega(782), \phi(1020), J/\psi(3097)$ and $\rh(1450), \rh(1700)$. Essential entities are the photon light-cone wave function of light-cone perturbation theory (LCPT) universalised to vanishing virtualities $Q$ and wave functions for the vectormesons modelled accordingly. We verify the SVM-specific mechanism of formation of interacting gluonic strings between the quark constituents.