125995373
The topological susceptibility with dynamical overlap fermions
117786356
Exotic baryons on the lattice
16594164
Low-lying fermion modes: Dynamical versus quenched
Abstract We compare the low-lying eigenmodes of the O(a) improved Wilson-Dirac operator on quenched and dynamical configurations and investigate methods of probing the topological properties of gauge configurations.
119392327
Improving the chiral properties of lattice fermions
The chiral properties of lattice fermions can be improved by altering either their fermion-gauge coupling or the pure gauge part of the action (or both). 
Using both perturbation theory and nonperturbative simulation, we compare a simple alteration of the gauge action (which encompasses the Wilson, Symanzik, Iwasaki, and DBW2 actions), and HYP-blocked links in the fermion action. Perturbative tests include calculations of the potential, flavor-changing quark scattering amplitudes, and matching factors for currents. Non-perturbative tests include the potential, measurements of flavor symmetry breaking for staggered fermions, the behavior of topological objects, and properties of overlap actions. Our results display the bad properties of these actions as well as their good ones.
117909068
High temperature quark localization by Polyakov loops
We study the low eigenmodes of the overlap and staggered Dirac operator at high temperature. We show that the recently found localized quark modes obeying Poisson statistics are connected to physical gauge field objects with their size and density scaling in the continuum limit. The localized modes are also strongly correlated with large fluctuations of the Polyakov loop. Based on that we construct a random matrix model of the low Dirac modes inspired by dimensional reduction. Our model reproduces the Poisson to random matrix transition seen in the lattice Dirac spectrum.
12447919
Absence of correlations in the QCD dirac spectrum at high temperature.
I propose a simple model of the distribution of the small eigenvalues of the QCD Dirac operator well above the finite temperature phase transition where chiral symmetry is restored and the spectral density at zero vanishes. Assuming the absence of correlations between different regions of the low-lying spectrum I derive analytic formulas for the distribution of the first two eigenvalues. I find good agreement with data obtained using the overlap Dirac operator in quenched SU(2) lattice simulations. This suggests that if chiral symmetry is restored spectral correlations are not important and all the statistical properties of the spectrum are encoded in the spectral density.
119496311
Overlapping Instantons
Overlapping instantons have an action density profile that significantly deviates from the simple addition of the density profiles of single instantons. This turns out to have important consequences for identifying the proper instanton content of a given configuration. Most dramatic is the case where the instantons are parallel in group space, leading to the effect of hiding large instantons. Sufficiently large instantons can have important contributions to a confining interaction.
207778110
Optimizing the Chiral Properties of Lattice Fermions
53865786
Monopoles and instantons in SU(2) lattice gauge theory
Abstract We investigate the monopole-instanton correlation in SU(2) lattice gauge theory using a renormalisation group inspired smoothing technique. We look at the properties of monopole clusters and their correlation with instantons. Since the action of the smoothed configurations is dominated by instantons we compare the smoothed Monte Carlo lattices to artificially reconstructed configurations with the same instanton content but no other fluctuations. Both parallel and randomly rotated (in group space) instanton ensembles are considered.
15283773
Structure of the QCD Vacuum as Seen by Lattice Simulations
This talk is a review of our studies of instantons and their properties as seen in our lattice simulations of SU(2) gauge theory. We have measured the topological susceptibility and the size distribution of instantons in t.he QCD vacuum. We have also investigated the properties of quarks moving in instanton background field configurations, where the sizes and locations of the instantons are taken from simulations of the full gauge theory. By themselves, these multi-instanton configurations do not confine quarks, but they induce chiral symmetry breaking.
16599272
Instantons and exceptional configurations with the clover action
We study exceptional modes of both the Wilson and the clover action in order to understand why quenched clover spectroscopy suffers so severely from exceptional configurations. We show that a large clover coefficient can make the exceptional modes extremely localized and thus very sensitive to short distance fluctuations. We contrast this with the case of the Wilson action where exceptional modes correspond to large instantons. These modes are broadly extended and suffer much less from discretization errors.