We present a calculation of the charmonium spectrum with three flavors of dynamical staggered quarks from gauge configurations that were generated by the MILC collaboration. We use the Fermilab action for the valence charm quarks. Our calculation of the spin-averaged 1P--1S and 2S--1S splittings yields a determination of the strong coupling, with \ams(MZ)=0.119(4).
@article{arxiv.hep-lat/0210051,
title = {Charmonium with three flavors of dynamical quarks},
author = {Massimo Di Pierro and Aida X. El-Khadra and Steven Gottlieb and Andreas S. Kronfeld and Paul B. Mackenzie and Damian P. Menscher and Mehmet B. Oktay and James N. Simone},
journal= {arXiv preprint arXiv:hep-lat/0210051},
year = {2009}
}