Determination of the Real Part of theρ-Nucleon Forward Scattering Amplitude and the RelativeρωProduction Phase

Abstract
The real part of the ρ-nucleon forward scattering amplitude has been obtained by a measurement of the photoproduction of asymmetric electron-positron pairs from a carbon target. A determination of the relative ρω production phase is also made. At a mean incident photon energy of 4 GeV the ratio of the real to the imaginary part of the ρ-nucleon amplitude is found to be - 0.28 ± 0.12.