Probing chiral-odd GPD's in diffractive electroproduction of two vector mesons

Abstract

We consider the electroproduction of two vector mesons with a large rapidity gap between them on a nucleon target in the process ${\gamma }^{\ast }N\to {\rho }_1{\rho }_2{N}^{\prime }$. We calculate the Born term for this process within the collinear factorization framework. The resulting scattering amplitude may be represented as a convolution of an impact factor describing the ${\gamma }^{\ast }\to {\rho }_1$ transition and an amplitude describing the $N\to {\rho }_2{N}^{\prime }$ transition. The latter amplitude is analogous to deeply virtual electroproduction of a meson, the virtual photon being replaced by two gluon (Pomeron) exchange . The long distance part of this amplitude is described by Generalized Parton Distributions (GPD) and meson light-cone distributions. The selection of a transversely polarized vector meson ${\rho }_2$ provides the first feasible selective access to chiral-odd GPD.

Comments: 12 pages LATEX, 2 .eps figures, revised version to appear in Phys Lett B. References and minor clarifications added, typos corrected