par Adloff, Catherine;Clerbaux, Barbara ;Favart, Laurent ;Marage, Pierre ; [et al.]
Référence Zeitschrift für Physik. C, Particles and fields, 74, page (221-235)
Publication Publié, 1997
Article révisé par les pairs
Résumé : A study is presented of the process γp → XY, where there is a large rapidity gap between the systems X and Y. Measurements are made of the differential cross section as a function of the invariant mass Mx of the system produced at the photon vertex. Results are presented at centre of mass energies of (W) = 187 GeV and 〈W〉 = 231 GeV, both where the proton dominantly remains intact and, for the first time, where it dissociates. Both the centre of mass energy and the Mx2 dependence of HERA data and those from a fixed target experiment may simultaneously be described in a triple-Regge model. The low mass photon dissociation process is found to be dominated by diffraction, though a sizable subleading contribution is present at larger masses. The pomeron intercept is extracted and found to be αP(0) = 1.068 ± 0.016 (stat.) ± 0.022 (syst.) ± 0.041 (model), in good agreement with values obtained from total and elastic hadronic and photoproduction cross sections. The diffractive contribution to the process γp → Xp with Mx2/W2 < 0.05 is measured to be 22.2 ± 0.6 (stat.) ± 2.6 (syst.) ± 1.7 (model) % of the total γp cross section at 〈W〉 = 187 GeV. © Springer-Verlag 1997.