Eur. Phys. J. A 16, 527-535 (2003)
DOI: 10.1140/epja/i2002-10120-y

Generalized Parton Distributions in Constituent Quark Models

S. Scopetta¹ and V. Vento<sup>2, 3

1</sup>  Dipartimento di Fisica, Università degli Studi di Perugia and INFN, sezione di Perugia, via A. Pascoli, 06100 Perugia, Italy
²  Departament de Fisica Teòrica and Institut de Física Corpuscular, Universitat de València - Consejo Superior de Investigaciones Científicas, 46100 Burjassot (València), Spain
³  School of Physics, Korea Institute for Advanced Study, Seoul 130-012, Korea

sergio.scopetta@pg.infn.it
vicente.vento@uv.es

(Received: 31 January 2002 / Revised: 10 October 2002 / Published online: 18 March 2003)

Abstract
An approach is proposed to calculate Generalized Parton Distributions (GPDs) in a Constituent Quark Model (CQM) scenario. These off-diagonal distributions are obtained from momentum space wave functions to be evaluated in a given non-relativistic or relativized CQM. The general relations linking the twist-two GPDs to the form factors and to the leading-twist quark densities are consistently recovered from our expressions. Results for the leading twist, unpolarized GPD, H, in a simple harmonic-oscillator model, as well as in the Isgur and Karl model, are shown to have the general behavior found in previous estimates. NLO evolution of the obtained distributions, from the low-momentum scale of the model up to the experimental one, is also shown. Further applications of the proposed formalism are addressed.

PACS
12.39.-x - Phenomenological quark models.
13.40.Gp - Electromagnetic form factors.
13.60.Hb - Total and inclusive cross sections (including deep-inelastic processes).

© Società Italiana di Fisica, Springer-Verlag 2003