2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 9, 491-501
DOI 10.1007/s100529900067

Odderon and photon exchange in electroproduction of pseudoscalar mesons

E.R. Berger1 - A. Donnachie2 - H.G. Dosch1 - W. Kilian3 - O. Nachtmann1 - M. Rueter4

1 Institut für Theoretische Physik der Universität Heidelberg, Philosophenweg 16, D-69120 Heidelberg, Germany (e-mail: e.berger, h.g.dosch, o.nachtmann@thphys.uni-heidelberg.de)
2 TH Division, CERN (e-mail: ad@a3.ph.man.ac.uk)
3 Institut für Theoretische Teilchenphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany (e-mail: kilian@particle.physik.uni-karlsruhe.de)
4 School of Physics and Astronomy, Department of High Energy Physics, Tel Aviv University, 69978 Tel Aviv, Israel (e-mail: rueter@post.tau.ac.il)

Received: 2 February 1999 / Revised version: 22 March 1999 / Published online: 28 May 1999

Abstract
We investigate the reaction ${\rm e}\;{\rm p} \rightarrow {\rm e}\;{\rm PS}\;{\rm X}$ where PS denotes a pseudoscalar meson $\pi^0$, $\eta$, $\eta'$, or $\eta_c$ and X either a proton or resonance or continuum state into which the proton can go by diffractive excitation. At high energies photon and odderon exchange contribute to the reaction. The photon exchange contribution is evaluated exactly using data for the total virtual photon-proton absorption cross section. The odderon exchange contribution is calculated in nonperturbative QCD, using functional integral techniques and the model of the stochastic vacuum. For the proton we assume a quark-diquark structure as suggested by the small odderon amplitude in ${\rm pp}$ and $ {\rm p} \bar{{\rm p}}$ forward scattering. We show that odderon exchange leads to a much larger inelastic than elastic PS production cross section. Observation of our reaction at HERA would establish the soft odderon as an exchange object on an equal footing with the soft pomeron and would give us valuable insight into both the nucleon structure and the mechanism of high energy diffractive scattering.


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