Abstract. We introduce generalized quark and gluon distributions in the deuteron, which can be measured in exclusive processes like deeply virtual Compton scattering and meson electroproduction. We discuss the basic properties of these distributions, and point out how they probe the interplay of nucleon and parton degrees of freedom in the deuteron wave function.Introduction. The partonic structure of the deuteron has been explored in terms of the parton distributions accessible in deep inelastic scattering [1], and in terms of the form factors measured in elastic lepton-deuteron processes [2,3]. It is natural to ask what can be learned from generalized parton distributions (GPDs), introduced not long ago in [4,5]. For the nucleon case it has been shown that these quantities contain unique information about the dynamics of quarks and gluons in QCD bound states, beyond what can be unraveled from ordinary parton distributions and form factors. Here we extend these studies to the case of the deuteron, with the aim of providing the theoretical framework to analyze and interpret present and future measurements with deuteron targets. We restrict ourselves to parton distributions of twist two, and to the parton helicity conserving sector, which is relevant in most phenomenological applications. Quark and gluon helicity flip GPDs can be treated with the same methods.

We investigate the exclusive photoproduction of a heavy timelike photon which decays into a lepton pair, gamma p -> l+ l- p. This can be seen as the analog of deeply virtual Compton scattering, and we argue that the two processes are complementary for studying generalized parton distributions in the nucleon. In an unpolarized experiment the angular distribution of the leptons readily provides access to the real part of the Compton amplitude. We estimate the possible size of this effect in kinematics where the Compton process should be dominated by quark exchange.Comment: 31 pages, 17 figure

Total and differential cross sections for high energy and small momentum transfer elastic hadron-hadron scattering are studied in QCD using a functional integral approach. The hadronic amplitudes are governed by vacuum expectation values of lightlike Wegner-Wilson loops, for which a matrix cumulant expansion is derived. The cumulants are evaluated within the framework of the Minkowskian version of the model of the stochastic vacuum. Using the second cumulant, we calculate elastic differential cross sections for hadron-hadron scattering. The agreement with experimental data is good.

We study the exclusive reactions π − p → ℓ + ℓ − n and π + n → ℓ + ℓ − p in view of possible future experiments with high-intensity pion beams. For large invariant mass of the lepton pair ℓ + ℓ − and small squared momentum transfer to the nucleon these are hard-scattering processes providing access to generalized parton distributions. We estimate the cross section for these reactions, explore their connection with the pion form factor, and discuss the role they can play in improving our understanding of the relevant reaction mechanisms. 1

We calculate high-energy photoproduction of the tensor meson f 2 (1270) by odderon and photon exchange in the reaction γ + p → f 2 (1270) + X, where X is either the nucleon or the sum of the N(1520) and N(1535) baryon resonances. Odderon exchange dominates except at very small transverse momentum, and we find a cross section of about 20 nb at a centre-of-mass energy of 20 GeV. This result is compared with what is currently known experimentally about f 2 photoproduction. We conclude that odderon exchange is not ruled out by present data. On the contrary, an odderon-induced cross section of the above magnitude may help to explain a puzzling result observed by the E687 experiment. 1