Abstract
Experimental cross sections for the reaction (γ,) at low energy have been used to deduce the isovector-multipole combination [2(v)+(v)]/qk for the nucleon near threshold. The effects of pion-wave distortion (distorted-wave impulse approximation) and Fermi motion in are addressed in detail. By incorporating additional constraints on certain combinations of the p-wave multipoles as deduced from the Mainz (γ,) data, near-threshold values are obtained for the reduced proton p-wave (γ,) multipoles /qk,/qk, and /qk which are in excellent agreement with the VPI multipoles as given by the said code but disagree with the findings of other authors. Combined with a conservative theoretical estimate of the isoscalar amplitude (s), these results permit a decomposition of (p) into isoscalar and isovector components in the near-threshold region.
- Received 1 April 1994
DOI:https://doi.org/10.1103/PhysRevC.50.2979
©1994 American Physical Society