UNRAVELING VIOLATIONS OF PARTON-HADRON DUALITY IN ep SCATTERING

Recent studies of the Q dependence of ep scattering in the large x region and in the Q range: 1 ≤ Q ≤ 30 Gev, 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. At lower values of W , 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 dependence of the data: at low W , non-partonic components given by color neutral clusters dominate the cross section and the Q dependence is governed by their mass spectrum, predicted within the preconfiment property of QCD; at large W 2 the structure function is determined by a convolution of the cluster mass spectrum with the parton distributions.