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Particles and Fields

Eur. Phys. J. C 25, 421-425 (2002)
DOI: 10.1007/s10052-002-0974-2

Two photon width of $\eta_c$

N. Fabiano1 and G. Pancheri2

1  Perugia University and INFN, via Pascoli 06100, Perugia, Italy
2  INFN National Laboratories, P.O. Box 13, 00044, Frascati, Italy

(Received: 25 October 2001 / Revised version: 7 March 2002 Published online: 30 August 2002 )

We discuss the measured partial width of the pseudoscalar charmonium state $\eta_c$ into two photons. Predictions from potential models are examined and compared with experimental values. On including radiative corrections, it is found that present measurements are compatible both with a QCD type potential and with a static Coulomb potential. The latter is then used to give an estimate on the $\eta_b$ decay into two photons. Results for $\eta_c$ are also compared with those from $J/\psi$ data through the NRQCD model.

© Società Italiana di Fisica, Springer-Verlag 2002