Helicity amplitudes in pion photoproduction
Asymptotic QCD predicts that, as energy increases, the differential cross section for pion photoproduction should depend on the energy squared s as s{sup {minus}7}. In addition, the helicity of the nucleon should be conserved. The differential cross section at 90{degrees} center-of-mass angle for each of the four pion-production channels is in reasonable agreement with this energy dependence for energies above s= 1.4 GeV{sup 2}. The question of helicity conservation can be investigated by looking at the four helicity amplitudes that describe the reaction. These amplitudes are calculated by a partial-wave analysis of data for differential cross sections and polarization measurements. The current VPI partial-wave analysis, for energies s< 4.3 GeV{sup 2} shows no evidence that the amplitudes vanish.
- OSTI ID:
- 374711
- Report Number(s):
- CONF-9304297--
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 2 Vol. 40; ISSN 0003-0503; ISSN BAPSA6
- Country of Publication:
- United States
- Language:
- English
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