The longitudinal asymmetry of the (e, e′ p) missing momentum distribution as a signal of color transparency

We use multiple scattering theory to evaluate the Q2 dependence of the forward-backward asymmetry, Az, of the missing momentum distribution in quasielastic A(e, e′, p) scattering, which is expected to be affected by color transparency. The novel features of our analysis are a consistent treatment of the structure of the ejectile state formed after absorption of the virtual photon by the struck proton and a careful evaluation of the background asymmetry induced by the nonvanishing real part of the proton-nucleon scattering amplitude. We find that the absolute magnitude of Az is dominated by this background at the Q2ʹs attainable at the Continuous Electron Beam Accelerator Facility. However, the Q2 dependence of the asymmetry is sensitive to the onset of color transparency, whose observation in high precision experiments appears to be feasible, particularly using light targets such as 12C or 16O.