Light quarks, zero modes, and exceptional configurations
- Fermilab, P.O. Box 500, Batavia, Illinois 60510 (United States)
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)
- Department of Physics, University of Virginia, Charlottesville, Virginia 22901 (United States)
In continuum QCD, nontrivial gauge topologies give rise to zero eigenvalues of the massless Dirac operator. In lattice QCD with Wilson fermions, analogs of these zero modes appear as exactly real eigenvalues of the Wilson-Dirac operator, leading to poles in the quark propagator in the vicinity of the critical hopping parameter. It is shown that {open_quotes}exceptional configurations,{close_quotes} which arise in the quenched approximation at small quark mass, are the result of the fluctuation of the position of zero mode poles to subcritical values of hopping parameter on particular gauge configurations. We describe a procedure for correcting these lattice artifacts by first isolating the contribution of zero mode poles to the quark propagator and then shifting the subcritical poles to the critical point. This procedure defines a modified quenched approximation in which accurate calculations can be carried out for arbitrarily small quark masses. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 567116
- Journal Information:
- Physical Review, D, Vol. 57, Issue 3; Other Information: PBD: Feb 1998
- Country of Publication:
- United States
- Language:
- English
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