Dr Michael Teper

Abstract:

We investigate how topological zero-modes affect hadron physics in the quenched approximation. We remark that in a finite volume the exact zero-modes render the chiral condensate pathological and explain why this is not observed in lattice calculations. We then provide an argument, supported by a model calculation, to show how the mixed 'zero-modes' produce a density of modes, λ, in the large volume limit that diverges as 1/√λ. This implies that the quark physics of quenched QCD becomes pathological in the continuum limit. We also show how similar arguments lead to a non-standard but regular spectrum in full QCD. © 1995 Elsevier Science B.V. All rights reserved.

Abstract:

We investigate what happens to confinement in lattice gauge fields that have been subjected to cooling. We prove that the local character of cooling is by itself enough to ensure that however many cooling sweeps we perform the cooled configurations will continue to be confining, with the usual string tension, at sufficiently large distances. We support the general theoretical arguments with explicit calculations in some simple models as well as with numerical calculations of Polyakov loop correlations. In addition we show that glueball masses can be extracted from cooled configurations in the same way as the string tension. We also compare the relative efficiencies of calculations of the string tension with and without cooling. We find that cooling, while it is an efficient method, possesses no clear advantage when compared to state-of-the-art methods without cooling. © 1984.

Abstract:

We perform finite temperature simulations of SU (2) lattice gauge fields in two spatial dimensions. We calculate the correlation length and find that it appears to diverge at a critical temperature, indicating a second order phase transition. Our average value for the associated critical exponent is γ = 0.975+0.045-0.035 which is consistent with the value γ = 1 in the D = 2 Ising model. We calculate the critical temperature, Tc, in units of the string tension, σ, and extrapolate to the continuum limit. If we use the theoretically favoured value, γ = 1, in our fits for Tc then we obtain Tc σ = 1.121 ± 0.008. If, instead, we allow γ tobe free then we obtain a somewhat less precise value: Tc σ = 1.118+0.034-0.016. We note that while this value is very different from the corresponding value in four dimensions, most of the difference can be understood on simple dimensional grounds. © 1993.

Abstract:

We investigate confinement in D = 3 SU(2) lattice gauge theory. We confirm the approximately linear character of confinement at large distances. The corresponding continuum string tension is found to be √σ/g2 = 0.3340 ± 0.0025. We also find that the flux is located within a tube and that the width of this flux tube is l0{reversed tilde equals} 1.22/Tc where Tc is the deconfining temperature. The dominant fluctuations of the confining flux tube appear to be simple wavelike oscillations. This is remarkably similar to the expected properties of confinement in four dimensions. © 1993.