Helicity Signatures in Subthreshold rho Production on Nuclei
We report a helicity analysis of subthreshold rho production on 2H and 12C nuclei at low photoproduction energies and large |t|. The results are indicative of a large longitudinal rho polarization (l=1, m=0) and are consistent with a strong helicity-flip mechanism of rho production. The analysis is model-independent and supports the large mass shift reported from the earlier 3He experiments.
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