Q2Dependence of Nuclear Transparency for Exclusiveρ0Production

Exclusive coherent and incoherent electroproduction of the ${\rho }^0$ meson from ${}^{\mathrm{1}}\mathrm{H}$ and ${}^{\mathrm{14}}\mathrm{N}$ targets has been studied at the HERMES experiment as a function of coherence length ($l_c$), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon ($-Q^2$). The ratio of ${}^{\mathrm{14}}\mathrm{N}$ to ${}^{\mathrm{1}}\mathrm{H}$ cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing $l_c$ for coherent (incoherent) ${\rho }^0$ electroproduction. For fixed $l_c$, a rise of nuclear transparency with $Q^2$ is observed for both coherent and incoherent ${\rho }^0$ production, which is in agreement with theoretical calculations of color transparency.