On the determination of double diffraction dissociation cross section at HERA

Abstract

The excitation of the proton into undetected multiparticle states (double diffraction dissociation) is an important background to single diffractive deep-inelastic processes ep →We present estimates of the admixture of the double diffraction dissociation events in all diffractive events. We find that in the J/Ψ photoproduction, electroproduction of the ρ 0 at large Q 2 and diffraction dissociation of real and virtual photons into high mass states X the contamination of the double diffraction dissociation can be as large as ∼ 30%, thus affecting substantially the experimental tests of the pomeron exchange in deep inelastic scattering at HERA. We discuss a possibility of tagging the double diffraction dissociation by neutrons observed in the forward neutron calorimeter. We present evaluations of the spectra of neutrons and efficiency of neutron tagging based on the experimental data for diffractive processes in the proton-proton collisions.

Exclusive leptoproduction of $\rho^0$ mesons from hydrogen at intermediate virtual photon energies

“…[22]. Taking into account other estimates of the ratio of double diffractive to single diffractive ρ 0 production also at lower Wvalues [24], which are smaller in general, a total systematic uncertainty of about 3% (relative to the measured cross section) has been assigned to the DD contribution. The small size of the DD contribution is related to the good energy resolution of the HERMES experiment (σ ∆E ≈ 0.25 GeV -see Fig.…”

Diffractive vector meson production

“…One can argue [114] that the relative importance of the elastic and proton-dissociative reaction is precisely the same as in proton-nucleus and proton-proton scattering described in Section 3.1.5. At small t within the diffraction cone the protondissociative production will be smaller than the elastic production but still the biggest background contribution to the elastic vector meson production.…”

“…The variation of the diffraction slope (35) from elastic scattering to single (SD) to double (DD) diffraction excitation exhibits certain universal features [93,94,114]. An excellent guidance is provided by a comparison of elastic proton-nucleus, pA → pA, to quasielastic, pA → p ′ A * , scattering.…”

Reggeons in Diffractive Interactions in Deep Inelastic Scattering at Hera

“…For small values of x I P relevant here only the πN contribution is of interest 15 . The analysis of the πN contribution to the structure function (1) is performed in 12 using the Deck mechanism 16 .…”