Nuclear Transparency in Exclusive ρ0 Production at HERMES

Abstract

Exclusive coherent and incoherent electroproduction of the ρ0 meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (lc), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four‐momentum of the virtual photon (−Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing coherence length for coherent (incoherent) ρ0 electroproduction. For fixed coherence length, a rise of nuclear transparency with Q2 is observed for both coherent and incoherent ρ0 production, which is in agreement with theoretical calculations of color transparency. © 2004 American Institute of Physics