We derive expressions for pion photoproduction amplitudes in the 1/N c 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/Nc2) is impressive.
|Original language||English (US)|
|Number of pages||12|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Apr 1 2005|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)