https://doi.org/10.1140/epja/i2008-10759-2
Regular Article - Theoretical Physics
Dual parametrization of GPDs versus the double distribution Ansatz
1
Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780, Bochum, Germany
2
Petersburg Nuclear Physics Institute, 188350, Gatchina, St. Petersburg, Russia
3
St. Petersburg State University, 198504, St. Petersburg, Petrodvoretz, Russia
* e-mail: semenovk@tp2.ruhr-uni-bochum.de
Received:
26
November
2008
Revised:
4
March
2009
Accepted:
19
March
2009
Published online:
18
April
2009
We establish a link between the dual parametrization of GPDs and a popular parametrization based on the double distribution Ansatz, which is in prevalent use in phenomenological applications. We compute several first forward-like functions that express the double distribution Ansatz for GPDs in the framework of the dual parametrization and show that these forward-like functions make the dominant contribution into the GPD quintessence function. We also argue that the forward-like functions 
with 
1 contribute to the leading singular small-xBj behavior of the imaginary part of DVCS amplitude. This makes the small-xBj behavior of 
independent of the asymptotic behavior of PDFs. Assuming analyticity of Mellin moments of GPDs in the Mellin space we are able to fix the value of the D -form factor in terms of the GPD quintessence function N(x, t) and the forward-like function Q
0(x, t) .
PACS: 13.60.Fz Elastic and Compton scattering – / 11.55.Hx Sum rules –
© SIF, Springer-Verlag Berlin Heidelberg, 2009
