Dual parametrization of GPDs versus the double distribution Ansatz

作者：Polyakov M V^*; Semenov Tian Shansky K M

来源：European Physical Journal A, 2009, 40(2): 181-198.

DOI：10.1140/epja/i2008-10759-2

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 Q(2 nu)(x) with nu >= 1 contribute to the leading singular small-x(Bj) behavior of the imaginary part of DVCS amplitude. This makes the small-x(Bj) behavior of ImA(DVCS) independent of the asymptotic behavior of PDFs. Assuming analyticity of Mellin moments of GPDs in the Mellin space we are able to. x 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).

• 出版日期2009-5