Background.
Although the properties of quarkonia are easy to estimate using
potential models, they are interesting for lattice QCD for just that
reason. Before the advent of good unquenched calculations, potential
models enabled one to estimate the effects of the quenched
approximation. Such quantities as αs and the heavy quark
masses could therefore be obtained with reasonable precision before
analogous quantities could be obtained from light quark
physics. Unquenched calculations will yield these quan- tities with
accuracies limited only by perturbation theory. In current
unquenched calculations, they serve several additional important
purposes. First, because they are well-understood with potential
models, one can expect particular quarkonium proper- ties to be very
sensitive to certain correction operators. For example, the
splitting of the χc states is expected to be very
sensitive to the O(v4) correction ψσ·
∇ × Eψ. Therefore, quarkonium calculations are
important test beds for improved actions. Second, quarkonium decays
test methods analogous to those of phenomenological crucial
heavy-light meson decays: leptonic decays of quarkonia are similar
to leptonic decays of heavy-lights, and electromagnetic transitions
of quarkonia are similar to semileptonic decays of
heavy-lights. Thus, a successful quarkonia program bolsters
confidence in the heavy-light program, and hence, lattice CKM
determinations. CLEO-c will improve dramatically the accuracy of
these charmonium decays over the next couple of years, making our
calculations of quarkonium properties timely in their own right.
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Abstract to the 2010 proposal.
This proposal is part of a coordinated effort to calculate
some of the most important quantities relevant for standard model
phenomenology. We propose a study of the masses of heavy quarkonium
states below open flavor threshold. Quarkonia are ideal for testing
improved heavy-quark actions, and verifying that their uncertainties
are well understood. In addition to providing new and precise
determinations of heavy-quark masses, comparison with existing and
upcoming experimental results will add an important test of lattice
QCD, aid in the interpretation of problematic excited quarkonium
states, and assist in the discovery of hybrid quarkonium states,
both exotic and nonexotic.
Results from previous support.
- Update on onium masses with three flavors of dynamical quarks. S. A. Gottlieb et al., PoS LAT2006:175, 2006.
- Update on doubly heavy meson spectroscopy. T. Burch, (2008, unpublished).
- Effects of the disconnected flavor singlet corrections on the hyperfine splitting in charmonium. C. DeTar and L. Levkova, POS LAT2007, 116 (2008)
- Contributions of charm anihilation to the hyperfine splitting. L. Levkova and C. DeTar, PoS LAT2008, 133 (2008).
- Quarkonium
mass splittings with Fermilab heavy quarks and 2+1 flavors of improved
staggered sea quarks. T. Burch et al, PoS LAT2009 (2010, to be published).
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Quarkonium mass splittings in three-flavor lattice QCD . T. Burch et
al., Phys. Rev. D81, 034508 (2010).
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