München 1997 – wissenschaftliches Programm
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T: Teilchenphysik
T 311: Postdeadlinesitzung
T 311.6: Vortrag
Mittwoch, 19. März 1997, 17:15–17:30, 217
Multihadronic Final States in Diffractive DIS at HERA — •J.M. Hernández, F. Barreiro, and L. Labarga — Universidad Autónoma de Madrid. Dpto. Física Teórica. E-28049 Madrid
We perform a global shape analysis of the multihadronic final states observed in deep inelastic scattering (DIS) events with a forward large rapitiy gap. These diffractive processes are generally believed to proceed via the exchange of a colour-singlet object with the vacuum quantum numbers call the pomeron. In order to get a deeper understanding of pomeron induced reactions in DIS, we study shape variables in the γ*−pomeron c.m. system and investigate their dependence on MX, the c.m. energy in this frame. This is in analogy with the by now classical studies of shape variables in e+e− annihilation as a function of √s which eventually led to the discovery of three jet events as a consequence of gluon bremstrahlung. We find that the broadening effects in the diffractive DIS final states are stronger than those observed in e+e−, and therefore an additional mechanism to hard gluon bremstrahlung is needed. We, together with J.Vermaseren, propose a model in which unlike in the Ingelman and Schlein approach, a partonic structure is not ascribed to the pomeron. Instead, the coupling of the pomeron to quarks or gluons is taken pointlike. This model, owing to the pointlike coupling of the pomeron to gluons gives a reasonable description of the ZEUS data.