We present results from a series of NRQCD simulations of the charmonium system, both in the quenched approximation and with n_f = 2 dynamical quarks. The spectra show evidence for quenching effects of ~10% in the S- and P-hyperfine splittings. We compare this with other systematic effects. Improving the NRQCD evolution equation altered the S-hyperfine by as much as 20 MeV, and we estimate radiative corrections may be as large as 40%.
Cite
@article{arxiv.hep-lat/0010015,
title = {Unquenched Charmonium with NRQCD - Lattice 2000},
author = {Chris Stewart and Roman Koniuk},
journal= {arXiv preprint arXiv:hep-lat/0010015},
year = {2009}
}