Sergio Scopetta

Quark model analysis of the Sivers function

We develop a formalism to evaluate the Sivers function. The approach is well suited for calculations which use constituent quark models to describe the structure of the nucleon. A nonrelativistic reduction of the scheme is performed and applied to the Isgur-Karl model of hadron structure. The results obtained are consistent with a sizable Sivers effect and the signs for the u and d flavor contributions turn out to be opposite. This pattern is in agreement with the one found analyzing, in the same model, the impact parameter dependent generalized parton distributions. The Burkardt sum rule turns out to be fulfilled to a large extent. We estimate the QCD evolution of our results from the momentum scale of the model to the experimental one and obtain reasonable agreement with the available data.

Towards a unified picture of constituent and current quarks

Using a simple picture of the constituent quark as a composite system of point-like partons, we construct the parton distributions by a convolution between constituent quark momentum distributions and constituent quark structure functions. We evaluate the latter at a low hadronic scale with updated phenomenological information, and we build the momentum distributions using well-known quark models. The resulting parton distributions and structure functions are evolved to the experimental scale and good agreement with the available DIS data is achieved. When compared with a similar calculation using non-composite constituent quarks, the accord with experiment of the present calculation becomes impressive. We therefore conclude that DIS data are consistent with a low energy scenario dominated by composite, mainly non-relativistic constituents of the nucleon.Abstract Using a simple picture of the constituent quark as a composite system of point-like partons, we construct the parton distributions by a convolution between constituent quark momentum distributions and constituent quark structure functions. We evaluate the latter at a low hadronic scale with updated phenomenological information, and we build the momentum distributions using well-known quark models. The resulting parton distributions and structure functions are evolved to the experimental scale and good agreement with the available DIS data is achieved. When compared with a similar calculation using non-composite constituent quarks, the accord with experiment of the present calculation becomes impressive. We therefore conclude that DIS data are consistent with a low energy scenario dominated by composite, mainly non-relativistic constituents of the nucleon.

Neutron structure function F(2)**n (x) from deep inelastic electron scattering off few nucleon systems

The possibility of a reliable extraction of the neutron deep inelastic structure function,

Double parton correlations and constituent quark models: a light front approach to the valence sector

F_2^n(x)

Model calculations of the Sivers function satisfying the Burkardt Sum Rule

, for

Analyzing the Boer-Mulders function within different quark models

x < 0.85

Generalized parton distributions and composite constituent quarks

from joint measurements of deep inelastic structure functions of deuteron,

A QUARK MODEL ANALYSIS OF THE TRANSVERSITY DISTRIBUTION

^{3}He

On the extraction of the neutron spin structure functions and the Gerasimov-Drell-Hearn integral from the process He→3(e→,e′) in the resonance region

and

Generalized parton distributions of He-3

^{3}H