Unexpected impact of D waves in low-energy neutral pion photoproduction from the proton and the extraction of multipoles
Author(s)Fernandez Ramirez, Cesar; Bernstein, Aron M; Donnelly, T William
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Contributions of D waves to physical observables for neutral pion photoproduction from the proton in the near-threshold region are studied and means to isolate them are proposed. Various approaches to describe the multipoles are employed-a phenomenological one, a unitary one, and heavy baryon chiral perturbation theory. The results of these approaches are compared and found to yield essentially the same answers. D waves are seen to enter together with S waves in a way that any means which attempt to obtain the E0+ multipole accurately must rely on knowledge of D waves and that consequently the latter cannot be dismissed in analyses of low-energy pion photoproduction. It is shown that D waves have a significant impact on double-polarization observables that can be measured. This importance of D waves is due to the soft nature of the S wave and is a direct consequence of chiral symmetry and the Nambu-Goldstone nature of the pion. F-wave contributions are shown to be negligible in the near-threshold region.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physical Review C
American Physical Society (APS)
Fernández-Ramírez, C., A. M. Bernstein, and T. W. Donnelly. “Unexpected Impact ofDwaves in Low-Energy Neutral Pion Photoproduction from the Proton and the Extraction of Multipoles.” Physical Review C 80, no. 6 (December 4, 2009).
Final published version