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arXiv · hep-ph/0410191

Helicity-dependent generalized parton distributions and composite constituent quarks

Sergio Scopetta·Vicente Vento
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Abstract

An approach, recently proposed to calculate the nucleon generalized parton distributions (GPDs) in a constituent quark model (CQM) scenario, in which the constituent quarks are taken as complex systems, is used to obtain helicity-dependent GPDs. They are obtained from the wave functions of the non relativistic CQM of Isgur and Karl, convoluted with the helicity-dependent GPDs of the constituent quarks themselves. The latter are modelled by using the polarized structure functions of the constituent quark, the double distribution representation of GPDs, and a phenomenological constituent quark form factor. The present approach permits to access a kinematical range corresponding to both the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi and the Efremov-Radyushkin-Brodsky-Lepage regions, for small values of the momentum transfer and of the skewedness parameter. In this kinematical region, the present calculation represents a prerequisite for the evaluation of cross sections relevant to deeply virtual Compton scattering. In particular, we have calculated the leading twist helicity-dependent GPD \tilde H and, from our expressions, its general relations with the non relativistic definition of the axial form factor and with the leading twist polarized quark density are consistently recovered.

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Sergio Scopetta, Vicente Vento. 2004-12-28. Helicity-dependent generalized parton distributions and composite constituent quarks. https://doi.org/10.1103/physrevd.71.014014

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