arXiv subjects

Werner Kerler

Publications and source records attributed to Werner Kerler.

22 records · Page 2Linked to original sources

arXiv1999

Dirac operator normality and chiral properties on the lattice

Normality in connection with $γ_5$-hermiticity determines the basic chiral properties and rules. The Ginsparg-Wilson (GW) relation is one of the allowed constraints on the spectrum. Interrelations between features of the spectrum, the sum rule for chiral differences of real modes and contributions to the Ward identity are pointed out. The alternative chiral transformation of Lüscher gives the same Ward identity as the usual one, in the global and in the local case. Imposing normality on a general function of the hermitean Wilson-Dirac (HWD) operator, inevitably leads at the same time to the Neuberger operator and to the GW relation. In this context also the case with zero eigenvalues of the HWD operator is handled. The eigenvalue flows of the HWD operator obey a differential equation the characteristic features of the solutions of which are discussed.

hep-lat↗

arXiv1994

Phase structure and monopoles in U(1) gauge theory

We investigate the phase structure of pure compact U(1) lattice gauge theory in 4 dimensions with the Wilson action supplemented by a monopole term. To overcome the suppression of transitions between the phases in the simulations we make the monopole coupling a dynamical variable. We determine the phase diagram and find that the strength of the first order transition decreases with increasing weight of the monopole term, the transition thus ultimately getting of second order. After outlining the appropriate topological characterization of networks of currents lines, we present an analysis of the occurring monopole currents which shows that the phases are related to topological properties.

hep-lat↗

arXiv1994

Simulated-tempering approach to spin-glass simulations

After developing an appropriate iteration procedure for the determination of the parameters, the method of simulated tempering has been successfully applied to the 2D Ising spin glass. The reduction of the slowing down is comparable to that of the multicanonical algorithm. Simulated tempering has, however, the advantages to allow full vectorization of the programs and to provide the canonical ensemble directly.

cond-mat↗

arXiv1994

Cluster mechanisms in the fully frustrated Ising model

The cluster algorithm in the fully frustrated Ising model on the square lattice is essentially different from the ones used in other systems. Thus its better understanding is particularly important for finding new lines of development. Therefore we investigate it in detail. In our simulations of high statistics more appropriate choices of the probability for freezing bonds and of that for flipping spins are seen to lead to better results. In an analysis of the topological properties we derive a set of rules for possible cluster configurations and give a classification by pairs of winding numbers.

cond-mat↗