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Can one see the number of colors in eta, eta-prime --> pi^+ pi^- gamma?

B. Borasoy·E. Lipartia
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Abstract

We investigate the decays eta, eta-prime --> pi^+ pi^- gamma up to next-to-leading order in the framework of the combined 1/N_c and chiral expansions. Counter terms of unnatural parity at next-to-leading order with unknown couplings are important to acommodate the results both to the experimental decay width and the photon spectrum. The presence of these coefficients does not allow for a determination of the number of colors from these decays.

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B. Borasoy, E. Lipartia. 2004-10-10. Can one see the number of colors in eta, eta-prime --> pi^+ pi^- gamma?. https://doi.org/10.1103/physrevd.71.014027

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