1997/02/04 by C. Adloff, C. Adloff et al. · 72 citations
Chemistry · Physics and Astronomy · #Chemistry #Diffraction #Dissociation (chemistry) #Graph #HERA #Hadron #High-Energy Particle Collisions Research #Invariant mass #Nuclear physics #Optics #Particle physics #Particle physics theoretical and experimental studies #Photon #Photon energy #Physics #Pomeron #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Rapidity #Scattering #Scattering cross-section #Vertex (graph theory) #hep-ex
paper · pdf · doi:10.1007/s002880050385
published in Zeitschrift für Physik C 74(2), 221-235 (Springer Nature) · 29 pages, latex, 6 Figures
arxiv created 1997/02/04 · openalex publication_date 1997/04/23 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
A study is presented of the process gamma p -->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 Wgp = 187 GeV and Wgp = 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 alphapom(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 gamma p --> Xp with mx2 / Wgp2 < 0.05 is measured to be 22.2 ± 0.6 (stat.) ± 2.6 (syst.) ± 1.7 (model) % of the total gamma p cross section at Wgp = 187 GeV.