Pion Photoproduction Amplitude Relations in the 1 / N c Expansion
نویسندگان
چکیده
Abstract We derive expressions for pion photoproduction amplitudes in the 1/Nc expansion of QCD, and obtain linear relations directly from this expansion that relate electromagnetic multipole amplitudes at all energies. The leading-order relations in 1/Nc compare favorably with available data, while the next-to-leading order relations seem to provide only a small improvement. However, when resonance parameters are compared directly, the agreement at O(1/Nc) or O(1/N 2 c ) is impressive.
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