出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The impact of dynamical fermions on the vacuum structure of QCD is explored. Of particular
interest is the topological charge correlator, hq(x)q(0)i, where negative values at small x reveal a
sign-alternating layered structure to the topological-charge density of the QCD vacuum. We consider
large 28396 lattices from the MILC collaboration, and develop a new gluonic definition of
the topological charge density, founded on a new over-improved stout-link smearing algorithm.
The algorithm reproduces established results from the overlap formalism and is designed to preserve
instantons. We examine the extent to which instanton-like objects are found on the lattice.
Finally, we investigate the effects of dynamical sea-quark degrees of freedom on topology and
find that the magnitudes of the negative dip in the hq(x)q(0)i correlator and the positive hq(0)2i
contact term are both increased with the introduction of dynamical fermion degrees of freedom.
This is in accord with expectations based on charge renormalization and the vanishing of the
topological susceptibility in the chiral limit.
