Dissociation of virtual photons in events with a leading proton at HERA

TL;DR

This paper investigates the dissociation of virtual photons in events with a leading proton at HERA, analyzing cross sections and structure functions across different Q^2 ranges to understand diffractive processes.

Contribution

It provides new measurements of the diffractive structure function F_2^D(3) and performs a NLO QCD fit incorporating recent and previous data, advancing understanding of diffraction in ep collisions.

Findings

Measured cross sections as functions of t, Phi, and Q^2.

Presented the diffractive structure function F_2^D(3).

Performed a NLO QCD fit to the data.

Abstract

The ZEUS detector has been used to study dissociation of virtual photons in events with a leading proton, gamma^* p -> X p, in e^+p collisions at HERA. The data cover photon virtualities in two ranges, 0.03<Q^2<0.60 GeV^2 and 2<Q^2<100 GeV^2, with M_X>1.5 GeV, where M_X is the mass of the hadronic final state, X. Events were required to have a leading proton, detected in the ZEUS leading proton spectrometer, carrying at least 90% of the incoming proton energy. The cross section is presented as a function of t, the squared four-momentum transfer at the proton vertex, Phi, the azimuthal angle between the positron scattering plane and the proton scattering plane, and Q^2. The data are presented in terms of the diffractive structure function, F_2^D(3). A next-to-leading-order QCD fit to the higher-Q^2 data set and to previously published diffractive charm production data is presented.