Aspects of QCD Vacuum Structure - High Energy Physics - LatticeReport as inadecuate

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Abstract: The impact of dynamical fermions on the vacuum structure of QCD is explored.Of particular interest is the topological charge correlator, $$,where negative values at small $x$ reveal a sign-alternating layered structureto the topological-charge density of the QCD vacuum. We consider large $28^3\times 96$ lattices from the MILC collaboration, and develop a new gluonicdefinition of the topological charge density, founded on a new over-improvedstout-link smearing algorithm. The algorithm reproduces established resultsfrom the overlap formalism and is designed to preserve instantons. We examinethe extent to which instanton-like objects are found on the lattice. Finally,we investigate the effects of dynamical sea-quark degrees of freedom ontopology and find that the magnitudes of the negative dip in the $$correlator and the positive $$ contact term are both increased with theintroduction of dynamical fermion degrees of freedom. This is in accord withexpectations based on charge renormalization and the vanishing of thetopological susceptibility in the chiral limit.

Author: Peter J. Moran, Derek B. Leinweber


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