Coherent vector meson electroproduction off the deuteron

QCD predicts Color Transparency (CT), which refers to nuclear medium becoming transparent to a small color neutral object produced in high momentum transfer reactions, due to reduced strong interaction. Despite several studies at BNL, SLAC, FNAL, DESY and Jefferson Lab, a definitive signal for CT still remains elusive. In this paper, we present the results of a new study at Jefferson Lab motivated by theoretical calculations that suggest fully exclusive measurement of coherent vector meson electroproduction off the deuteron is a favorable channel for studying CT. Vector meson production has a large cross section at high energies, and the deuteron is the best understood and simplest nuclear system. Exclusivity allows the production and propagation to be controlled separately by controlling $Q^2$, $l_f$ (formation length), $l_c$ (coherence length) and $t$. This control is important as the rapid expansion of small objects increases their interaction probability and masks CT. The CT signal appears in a ratio of cross sections at high $-t$ (where rescattering is significant) to low $-t$ (where single nucleon reactions dominate).