出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：In calculations of the hyperfine splitting in charmonium, the contributions of the disconnected
diagrams is considered small and is typically ignored. We aim to estimate nonperturbatively
the size of the resulting error, which could potentially affect the high precision calculations of
the charmonium spectrum. Following our work on the effects of the disconnected diagrams in
unquenched QCD presented at Lattice 2007, we study the same problem in the quenched case.
On dynamical ensembles the disconnected charmonium propagators contain light modes which
complicate the extraction of the signal at large distances. In the fully quenched case, where there
are no such light modes, the interpretation of the signal is simplified. We present results from
lattices with a ≈ 0.09 fm and a ≈ 0.063 fm.
