3He structure and generalized parton distribution

Abstract

Nuclear Generalized Parton Distributions (GPDs), a unique tool to access several crucial features of nuclear structure, could be measured in the coherent channel of hard exclusive processes, such as deep electroproduction of photons and mesons off nuclear targets. Here, a realistic microscopic calculation of the unpolarized quark GPD H_q^3 of the ^3He nucleus is described. In Impulse Approximation, H_q^3 is shown to be given by a convolution between the GPD of the internal nucleon and the non-diagonal spectral function, describing properly Fermi motion and binding effects. The obtained formula has the correct limits. Nuclear effects, evaluated by a modern realistic potential, are found to be larger than in the forward case. In particular, they increase with increasing the momentum transfer and the asymmetry of the process. Besides, it is found that the nuclear GPD cannot be factorized into a Δ^2-dependent and a Δ^2-independent term, as suggested in prescriptions proposed for finite nuclei. The dependence of the obtained GPDs on different realistic potentials used in the calculation shows that these quantities are sensitive to the details of nuclear structure at short distances.