Eur. Phys. J. A 14, 95-103 (2002)
DOI: 10.1140/epja/iepja1332

Single-spin asymmetry parameter from deeply virtual Compton scattering of hadrons up to twist-3 accuracy

I. Pion case

I.V. Anikin^{1, 2}, D. Binosi^{1, 3}, R. Medrano¹, S. Noguera¹ and V. Vento<sup>1, 3, 4

1</sup>  Departamento de Física Teórica, Universidad de Valencia, E-46100 Burjassot, Spain
²  Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia
³  IFIC-CSIC, E-46071 Valencia, Spain
⁴  School of Physics, Korea Institute for Advanced Study, Seoul 130-012, Korea

Vicente.Vento@uv.es

(Received: 7 November 2001 / Revised version: 6 February 2002 Communicated by A. Schäfer)

Abstract
The study of deeply virtual Compton scattering (DVCS) has shown that electromagnetic gauge invariance requires, to leading order, not only twist-two but additional twist-three contributions. We apply this analysis and, using the Ellis-Furmanski-Petronzio factorization scheme, compute the single- (electron) spin asymmetry arising in the collision of longitudinally polarized electrons with hadrons up to twist-3 accuracy. In order to simplify the kinematics we restrict the actual calculation to pions in the chiral limit. The process is described in terms of the generalized parton distribution functions which we obtain within a bag model framework.

PACS
13.60.Fz - Elastic and Compton scattering.
12.38.Bx - Perturbative calculations.

© Società Italiana di Fisica, Springer-Verlag 2002