Abstract
We report a helicity analysis of subthreshold production on , and at low photoproduction energies. The results are indicative of a large longitudinal polarization and are consistent with a strong helicity-flip production mechanism. This signature is used to extract in-medium invariant mass distributions for all three nuclei in a manner which is less model dependent than previous measurements. The results are compared to kinematic and phenomenological models of the spectral function. The and data distributions support the role of excitation in shaping the in-medium invariant mass distribution, while the distributions are consistent with quasi-free production. The data support an in-medium modification of the invariant mass distribution.
16 More- Received 21 July 2003
DOI:https://doi.org/10.1103/PhysRevC.68.065202
©2003 American Physical Society