Since present Monte Carlo algorithms for lattice QCD may become trapped in a fixed topological charge sector, it is important to understand the effect of calculating at fixed topology. In this work,â€¦ (More)

The SU (N f) L âŠ— SU (N f) R chiral symmetry of QCD is of central importance for the nonpertur-bative low-energy dynamics of light quarks and gluons. Lattice field theory provides a theoreticalâ€¦ (More)

Using a loop-cluster algorithm we investigate the spin 1 2 Heisenberg antiferromagnet on a square lattice with exchange coupling J and an additional four-spin interaction of strength Q. We confirmâ€¦ (More)

In the presence of a chemical potential, the physics of level crossings leads to singularities at zero temperature, even when the spatial volume is finite. These singularities are smoothed out at aâ€¦ (More)

We propose a new approach to the fermion sign problem in systems where there is a coupling U such that when it is infinite the fermions are paired into bosons, and there is no fermion permutationâ€¦ (More)

The recently proposed fermion-bag approach is a powerful technique to solve some four-fermion lattice field theories. Because of the existence of a duality between strong and weak couplings, theâ€¦ (More)

We formulate lattice theories in which chiral symmetry is realized nonlinearly on the fermion fields. In this framework the fermion mass term does not break chiral symmetry. This property allows usâ€¦ (More)

We study the anomalous breaking of UA(1) symmetry just above the QCD phase transition for zero and two flavors of quarks, using a staggered fermion, lattice discretization. The properties of the QCDâ€¦ (More)

We construct an efficient MonteÂ Carlo algorithm that overcomes the severe signal-to-noise ratio problems and helps us to accurately compute the conformal dimensions of large-Q fields at theâ€¦ (More)