Eur. Phys. J. C (2008) 58: 193-215
https://doi.org/10.1140/epjc/s10052-008-0741-0

Regular Article - Theoretical Physics

Sum rules and dualities for generalized parton distributions: is there a holographic principle?

¹ Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, 10002, Zagreb, Croatia
² Institut für Theoretische Physik II, Ruhr-Universität Bochum, 44780, Bochum, Germany
³ Theoretical Physics Division, Rudjer Bošković Institute, P.O. Box 180, 10002, Zagreb, Croatia

^* e-mail: passek@thphys.irb.hr

Received: 7 August 2008
Revised: 22 September 2008
Published online: 9 October 2008

Abstract

To leading order approximation, the physical content of generalized parton distributions (GPDs) that is accessible in deep virtual electroproduction of photons or mesons is contained in their value on the cross-over trajectory. This trajectory separates the t-channel and s-channel dominated GPD regions. The underlying Lorentz covariance implies correspondence between these two regions through their relation to GPDs on the cross-over trajectory. This point of view leads to a family of GPD sum rules which are a quark analogue of finite energy sum rules and it guides us to a new phenomenological GPD concept. As an example, we discuss the constraints from the JLab/Hall A data on the dominant u-quark GPD H. The question arises whether GPDs are governed by some kind of holographic principle.