Dr Michael Teper

Abstract:

We study the continuum limit of the length spectrum of magnetic monopole structures found after various Abelian projections of pure gauge SU(2), including the maximally Abelian gauge. We comment on Gribov copies, and measurements of the string tension.

Abstract:

We show that SU (Nc) gauge theories in 2+1 dimensions are close to Nc = ∞ for Nc ≥ 2. The dimensionful coupling, g2, is proportional to 1/Nc, at large Nc, confirming the usual diagram-based expectation. Preliminary calculations in 3+1 dimensions indicate that the same is true there.

Abstract:

We calculate the masses of the low-lying states with quantum numbers JPC = 0++,1-- in the Higgs and confinement regions of the three-dimensional SU(2) Higgs model, which plays an important rôle in the description of the thermodynamic properties of the standard model at finite temperatures. We extract the masses from correlation functions of gauge-invariant operators which are calculated by means of a lattice Monte Carlo simulation. The projection properties of our lattice operators onto the lowest states are greatly improved by the use of smearing techniques. We also consider cross correlations between various operators with the same quantum numbers. From these the mass eigenstates are determined by means of a variational calculation. In the symmetric phase, we find that some of the ground-state masses are about 30% lighter than those reported from previous simulations. We also obtain the masses of the first few excited states in the symmetric phase. Remarkable among these is the occurrence of a 0++ state composed almost entirely of gauge degrees of freedom. The mass of this state, as well as that of its first excitations, is nearly identical to the corresponding glueball states in three-dimensional SU(2) pure gauge theory, indicating an approximate decoupling of the pure gauge sector from the Higgs sector of the model. We perform a detailed study of finite-size effects and extrapolate the lattice mass spectrum to the continuum.

Abstract:

We study the Abelian projection of SU(2) instantons in the maximally Abelian gauge. We find that in this gauge an isolated instanton produces a closed monopole loop within its core and the size of this loop increases with the core size. We show that this result is robust against the introduction of small quantum fluctuations. We investigate the effects of neighbouring (anti-) instantons upon each other and show how overlapping (anti-) instantons can generate larger monopole loops. We find, however, that in fields that are typical of the fully quantised vacuum only some of the large monopole loops that are important for confinement have a topological origin. We comment on what this may imply for the rôle of instantons in confinement and chiral symmetry breaking.

Abstract:

We calculate on the lattice the interface tension in the SU(2) pure gauge theory in d = 2+1 at high temperature. The result is compared to the perturbative prediction. The agreement confirms applicability of the perturbation theory in this case. © 1995 Elsevier Science B.V. All rights reserved.