Latest results on diffraction at HERA

AGH University of Science and Technology, Faculty of Physics and Applied Computer Science Al. Mickiewicza 30, 30-059 Cracow, Poland

^a e-mail: Mariusz.Przybycien@agh.edu.pl

Published online: 3 August 2018

Abstract

Recent results on diffraction from the H1 and ZEUS experiments at HERA are presented. Measurement of open charm production in diffractive DIS has been performed by the H1 experiment using the event topology, given by ep → eXY, where the system X, containing at least one D^*(2010) meson, is separated from a leading low-mass proton dissociative system Y by a large rapidity gap. The photoproduction of isolated photons is measured using diffractive events recorded by the ZEUS experiment. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges 5 < E^γ_T < 15 GeV and -0:7 < η_γ < 0:9, inclusively and with a jet with transverse-energy and pseudorapidity in the ranges 4 < E^jet_T < 35 GeV and -1:5 < η_jet < 1:8. The exclusive deep inelastic electroproduction and photoproduction of Ψ(2S ) and J=Ψ(1S) mesons has been also studied by ZEUS. The cross-section ratio σ(Ψ(2S))=σ(J=Ψ(1S)) has been measured as a function of Q², W and t. The results are compared to several predictions of QCD-inspired models, providing tests of the models in a region of soft to hard diffraction.