Unraveling Violations of Parton-Hadron Duality in ep Scattering

Abstract

Recent studies of the Q^2 dependence of ep scattering in the large x region and in the Q^2 range: 1 < Q^2 <leq 30 Gev^2, confirm the validity of the phenomenon of quark-hadron duality - the similarity of the deep inelastic (parton) and resonance (hadron) spectra - for values of the invariant mass, W^2 > 2.4 GeV^2 At lower values of W^2, duality is found to be significantly violated by an amount that cannot be parametrized in terms of the first few terms of a series of power corrections. We present a dynamical model that explains the Q^2 dependence of the data: at low W^2, non-partonic components given by color neutral clusters dominate the cross section and the Q^2 dependence is governed by their mass spectrum, predicted within the preconfiment property of Q CD; at large W^2 the structure function is determined by a convolution of the cluster mass spectrum with the parton distributions.