https://doi.org/10.1140/epjc/s2004-01713-9
theoretical physics
The number of colors in the decays 
Physik Department, Technische Universität München, 85747, Garching, Germany
* e-mail: borasoy@ph.tum.de
The decays 
are investigated up to next-to-next-to-leading order in the framework of the combined 1/N
c
and chiral expansions. Without mixing of the pseudoscalar mesons the N
c
independence of the 
and 
decay amplitudes is shown to persist at the one-loop level, although the contribution of the Wess-Zumino-Witten term to the pertinent vertices is not canceled by the N
c
dependent part of a Goldstone-Wilczek term. The decay amplitude of the singlet field, on the other hand, depends strongly on N
c
and yields under the inclusion of mixing also a strong N
c
dependence for the decay. Both the and 
decay are suited to confirm the number of colors to be N
c
= 3.
© Springer-Verlag, 2004
