The Role of the Coherence Length in Exclusive Electroproduction of Vector Mesons off Nuclei

Abstract

The variation of the coherence length $l_c=2\nu /(Q^2+m_V^2)$ in virtual photoproduction of vector mesons off nuclei as a function of the photon energy $\nu$ or virtuality $Q^2$ results in dramatic changes in the values of the nuclear transparency. Color transparency effects can be easily mixed up with the effects of the coherence length in incoherent photoproduction on nuclei.

Comments: 5 pages, latex file and 6 uuencoded figures; Invited talk given by B. Kopeliovich at the ELFE Workshop, Cambridge, 22-29 July, 1995