Deeply virtual Compton scattering in the tensor-pomeron approach

Piotr Lebiedowicz; Otto Nachtmann; Antoni Szczurek

doi:10.1016/j.physletb.2022.137497

paper

Deeply virtual Compton scattering in the tensor-pomeron approach

arXiv:2208.12693 · doi:10.1016/j.physletb.2022.137497

Abstract

The two-tensor-pomeron model proposed previously to describe low $x$ DIS data is applied to real and virtual Compton scattering on a proton. The model includes two tensor pomerons, a soft and a hard one, and tensor reggeons. We include contributions of both transverse and longitudinal virtual photons. We show that this model gives a very good description of experimental data at small Bjorken $x$ on deeply virtual Compton scattering (DVCS) from HERA. The reggeon exchange term is particularly relevant for describing the real-photon-proton scattering measured at lower $γ p$ energies at FNAL. We present two fits which differ somewhat in the strength of the hard pomeron contribution. In both fits we find that the interference between soft- and hard-pomeron exchange plays an important role. We find that in DVCS the soft-pomeron contribution is considerable up to $Q^{2} \sim 20$ GeV $^{2}$ . Our model allows to study the transition from the small- $Q^{2}$ regime, including the photoproduction ( $Q^{2} = 0$ ) limit, to the large- $Q^{2}$ regime, the DIS limit. We also discuss the ratio of cross sections for longitudinally and transversely polarized virtual photons in $γ^{*} p \to γ p$ as a function of $∣ t ∣$ and $Q^{2}$ . The ratio $R ~ (Q^{2}, W^{2}, t) = (d σ_{L} / d t) / (d σ_{T} / d t)$ strongly increases with $t$ . Our findings may be checked in future lepton-nucleon scattering experiments in the low- $x$ regime, for instance, at a future Electron-Ion Collider at the BNL (EIC), and, if LHeC is realized, at the LHC.

arXiv comment20 pages, 7 figures

Deeply virtual Compton scattering in the tensor-pomeron approach

Abstract

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