Impact of Dynamical Fermions on QCD Vacuum Structure

Understand

We examine how dynamical fermions affect both the UV and infrared structure of the QCD vacuum.

• We consider large $28^3 \times 96$ lattices from the MILC collaboration, using a 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 nontrivial topological objects including instantons.
• At short distances we focus on the topological charge correlator, $<q(x) q(0) >$, where negative values at small $x$ reveal a sign-alternating layered structure to the topological-charge density of the QCD vacuum.