Nuclear Physics

Researchers from Perugia and Rome have set up a framework to carefully study nuclear effects in SIDIS, through a realistic spin-dependent spectral function which takes care of the final state interaction. This tool will be used now to evaluate SIDIS off transversely polarized 3He to support the experimental activity, in particular at Jlab, aimed to extract parton transverse momentum distributions in the neutron.

Relativity can be naturally implemented into our scheme within a Light Front approach through a LF spin-dependent spectral function. Preliminary results have already been obtained and will be extended also to the evaluation of the European Muon Collaboration effect, a long-standing problem in DIS off nuclei, for which recent data, for the 3He target, are available.

Special attention will be dedicated to the dynamical structure of mesons and nucleons through the study of the Bethe-Salpeter equation in Minkowsky space.

A novel approach for getting true solutions of the 4D Bethe-Salpeter equation directly in Minkowski space will be applied to a relativistic system, composed by a fermion and a boson interacting through the exchange of bosons, as a quark-diquark model for the nucleon. The main ingredient is the Nakanishi integral representation of the Bethe-Salpeter amplitude, embedded in a light-front framework.

The approach has already shown its ability to get both masses and light-cone distributions for bound systems composed by scalars, in ladder approximations. Currently, its extension to two fermion systems and to kernels beyond the ladder approximation is being carried on.

Moreover, solutions for scattering states are becoming available, and this will offer a novel path for estimating the final state effects, when relativistic particles are interacting.

Obtaining genuine and reliable solutions in the physical 4D space opens unprecedented possibilities to evaluate dynamical quantities for relativistic composite systems.