出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Experimentally the charmoniumhyperfine splitting is MJ=y Mhc
=117 MeV and current lattice
results are generally below this value. The difference could be due to the effects of the disconnected
flavor singlet diagrams which have not been included in these calculations. Previous
attempts to determine the disconnected flavor singlet corrections have led just to rough estimates
in the range of 20 MeV. We present preliminary results for these corrections calculated on fine
(a 0:09 fm) Asqtad 2+1 flavor lattices provided by the MILC Collaboration.
