High-energy elementary amplitudes from quenched and full QCD
arXiv:hep-ph/0307067 · doi:10.1016/j.physletb.2003.07.021
Abstract
Making use of the Stochastic Vacuum Model and the gluon gauge-invariant two-point correlation function, determined by numerical simulation on the lattice in both quenched approximation and full QCD, we calculate the elementary (quark-quark) scattering amplitudes in the momentum transfer space and at asymptotic energies. Our main conclusions are the following: (1) the amplitudes decrease monotonically as the momentum transfer increases; (2) the decreasing is faster when going from quenched approximation to full QCD (with decreasing quark masses) and this effect is associated with the increase of the correlation lengths; (3) dynamical fermions generate two components in the amplitude at small momentum transfer and the transition between them occurs at momentum transfer near 1 GeV. We also obtain analytical parametrizations for the elementary amplitudes, that are suitable for phenomenological uses, and discuss the effects of extrapolations from the physical regions investigated in the lattice.
6 pages, 4 figures, aps-revtex4, to be published in Physics Letters B