Abstract :
A method is described for calculating the Generalized Parton Distributions (GPDs) of spin 1/2 hadrons made of composite constituents, in an Impulse Approximation framework. GPDs are obtained from the convolution between the light cone non-diagonal momentum distribution of the hadron and the GPD of the constituent. DIS structure functions and electromagnetic form factors are consistently recovered with the proposed formalism. Results are presented for the nucleon and for the 3He nucleus. For a nucleon assumed to be made of composite constituent quarks, the proposed scheme permits to study the so-called Efremov-Radyushkin-Brodsky-Lepage (ERBL) region, difficult to access in model calculations. Results are presented for both helicity-independent and helicity-dependent GPDs. For 3He, the calculation has been performed by evaluating a non-diagonal spectral function within the AV18 interaction. It turns out that a measurement of GPDs for 3He could shed new light on the short-range nuclear structure at the quark level.
