Tamhankar, S (reprint author), Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 USA.
We present the first study of the charmonium spectrum using overlap fermions, on quenched configurations. Simulations are performed on 16(3) x 72 lattices, with Wilson gauge action beta = 6.3345. We demonstrate that we have discretization errors, as indicated by the dispersion relation, at about 5%. We obtain 88(4) MeV for the IS hyperfine splitting using the r(0) scale, and 121(6) MeV using the (1 (P) over bar -1 (S) over bar) scale. This Letter should encourage the pursuit of using the same chiral fermions for both heavy and light quarks on the same lattice. (c) 2006 Elsevier B.V. All rights reserved.