Abstract
The tensor-pomeron model is applied to low-x deep-inelastic lepton-nucleon scattering and photoproduction. We consider c.m. energies in the range 6 - 318 GeV and Q^2 < 50 GeV^2. In addition to the soft tensor pomeron, which has proven quite successful for the description of soft hadronic high-energy reactions, we include a hard tensor pomeron. We also include f_2-reggeon exchange which turns out to be particularly relevant for real-photon-proton scattering at c.m. energies in the range up to 30 GeV. The combination of these exchanges permits a description of the absorption cross sections of real and virtual photons on the proton in the same framework. In particular, a detailed comparison of this two-tensor-pomeron model with the latest HERA data for x < 0.01 is made. Our model gives a very good description of the transition from the small-Q^2 regime where the real or virtual photon behaves hadron-like to the large-Q^2 regime where hard scattering dominates. Our fit allows us, for instance, a determination of the intercepts of the hard pomeron as 1.3008(+73,-84), of the soft pomeron as 1.0935(+76,-64), and of the f_2 reggeon. We find that in photoproduction the hard pomeron does not contribute within the errors of the fit. We show that assuming a vector instead of a tensor character for the pomeron leads to the conclusion that it must decouple in real photoproduction.
Highlights
In this article we will be concerned with the structure functions of deep inelastic electron- and positron-proton scattering (DIS)
We show that assuming a vector instead of a tensor character for the Pomeron leads to the conclusion that it must decouple in real photoproduction and in the DIS structure functions
II we review the kinematics of DIS and some general relations for the DIS structure functions
Summary
In this article we will be concerned with the structure functions of deep inelastic electron- and positron-proton scattering (DIS). The exchange of a tensor Pomeron involves for the virtual photon γÃ-Pomeron coupling two functions which are in essence related to the γÃ-proton cross sections σT and σL, respectively. It is a special aim of our investigations to fit with our model simultaneously σT and σL. From fits to the structure functions of DIS, going down in Q2 to photoproduction ðQ2 1⁄4 0Þ, we shall be able to extract the properties of P0 and P1 and their couplings to virtual photons. In Appendixes D, E, and F we give details of our fit procedure and of the fit results
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