Dresden 2000 – wissenschaftliches Programm

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T: Teilchenphysik

T 501: QCD 5

T 501.7: Vortrag

Donnerstag, 23. März 2000, 11:45–12:00, H\,01

Diffractive Dijet Electroproduction at HERA — •F.-P. Schilling — Univ. Heidelberg, Physikalisches Institut

Deep-inelastic scattering (DIS) events at HERA containing large rapidity gaps have dominantly been ascribed to a diffractive or pomeron exchange mechanism. Diffractive DIS events which contain a dijet system are particularly sensitive to the underlying QCD dynamics of the process, because they directly probe the gluonic structure of the diffractive exchange. New results, obtained with the H1 Detector at HERA, are presented for the production of high p_T jet pairs as components of the dissociating photon system X in the diffractive DIS process ep → eXY, where the Y system is dominantly a proton and x_IP and |t| are small. The dijet cross sections, as well as the properties of the part of the hadronic final state which does not belong to the dijet system, are well described by a resolved pomeron model with gluon dominated pomeron parton distributions, obtained from a QCD analysis of F₂^D(3)(β, Q², x_IP). The data are also compared to models for diffractive DIS based either on ordinary DIS with additional final state soft colour interactions or on the exchange of two perturbative gluons between the proton and the qq and qqg Fock states of the virtual photon. The "semiclassical approach" and the "saturation model" for diffractive DIS are also confronted with the data.