Some views on monopoles and confinement

Aspects of the monopole condensation picture of confinement are discussed. First, the nature of the monopole singularities in the abelian projection approach is analysed. Their apparent gauge dependence is shown to have a natural interpretation in terms of 't~Hooft-Polyakov-like monopoles in euclidean SU(2) gauge theory. Next, the results and predictions of a realization of confinement through condensation of such monopoles are summarized and compared with numerical data.Comment: Talk at the International RCNP Workshop on COLOR CONFINEMENT AND HADRONS --- CONFINEMENT 95 (March 22--24, 1995, RCNP Osaka, Japan), to appear in the proceedings. 9 pages latex, 1 PostScript figure in uufiles format, uses epsf.te

RTNN: The new parallel machine in Zaragoza

I report on the development of RTNN, a parallel computer designed as a 4^4 hypercube of 256 T9000 transputer nodes, each with 8 MB memory. The peak performance of the machine is expected to be 2.5 Gflops.Comment: 10 pages PostScript, including 5 figures. Write-up (June 1995) of talk at the International Workshop ``QCD on Massively Parallel Computers'', Yamagata, Japan, 16-18 March 1995. To appear in the Proceedings, Suppl. Progr. Theor. Phys. (Kyoto

Lattice Computation of a Magnetic Monopole Mass

A single magnetic monopole in pure SU(2) gauge theory is simulated on the lattice and its mass is computed in the full quantum theory. The results are relevant for our proposed realization of the dual superconductor hypothesis of confinement.Comment: 3 pages PostScript, to appear in the Proceedings of IMACS93 (St. Louis, USA, Oct. 1993). Registration numbers ITFA-93-38 (Amsterdam), DFTUZ/93/21 (Zaragoza

A class of chiral fermion models

We study the relation between the Roma and Zaragoza proposals for chiral fermions on the lattice. The fermion action in the Roma approach is shown to be equivalent to one of the Zaragoza type. This result is used to perform a mean-field study of the phase diagram for chiral Yukawa models based on the Roma action. The phase diagram is compared with the one based on the Zaragoza model with the most local choice for the fermion interactions.Comment: Version to appear in Nucl. Phys. B. Some general discussion added to the Introduction and Conclusion sections. Now 33 pages Latex; style files and (unchanged) PostScript figures again attached in uufiles forma

Three topics in the Schwinger model

1. We compare Monte Carlo results with analytic predictions for the fermion condensate, in the massive one-flavour Schwinger model. 2. We illustrate on the Schwinger model how to facilitate transitions between topological sectors by a simple reweighting method. 3. We discuss exact, non-perturbative improvement of the gauge sector.Comment: Three-page contribution to Lat '97 by A.J. van der Sijs. Colourful typo (IR -> UV) correcte