name

Christopher Robert Stewart

refid

16931

email

kipper@yorku.ca

title

Unquenched Charmonium with Lattice NRQCD

collaboration

Roman Koniuk

abstract

We present the results from a series of lattice simulations of the charmonium system using a
highly-improved NRQCD action, both in the quenched approximation, and with n_f = 2 light
dynamical quarks. The spectra show some evidence for quenching effects of roughly 10% in
the S- and P-hyperfine spin splittings, considerably smaller than other systematic errors such as
the choice of tadpole correction factor and radiative corrections. We conclude
that quenching is just one of a collection of important effects that require attention in
precision heavy-quark simulations.

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