Dr Michael Teper

Abstract:

We compute glueball masses for even spins ranging from 0 to 6, in the D = 2 + 1 SU(2) lattice gauge theory. We do so over a wide range of lattice spacings, and this allows a well-controlled extrapolation to the continuum limit. When the resulting spectrum is presented in the form of a Chew-Frautschi plot we find that we can draw a straight Regge trajectory going through the lightest glueballs of spin 0, 2, 4 and 6. The slope of this trajectory is small and turns out to lie between the predictions of the adjoint-string and flux-tube glueball models. The intercept we find, α0∼-1, is much lower than is needed for this leading trajectory to play a 'Pomeron-like' role of the kind it is often believed to play in D = 3 + 1. We elaborate the Regge theory of high-energy scattering in 2 space dimensions, and we conclude, from the observed low intercept, that high-energy glueball scattering is not dominated by the leading Regge pole exchange, but rather by a more complex singularity structure in the region 0≤Reλ≤1/2 of the complex angular momentum λ plane. We show that these conclusions do not change if we go to larger groups, SU(N>2), and indeed to SU(∞), and we contrast all this with our very preliminary calculations in the D = 3 + 1 SU(3) gauge theory. © 2003 Elsevier B.V. All rights reserved.

Abstract:

We discuss the principles underlying higher spin glueball calculations on the lattice. For that purpose, we develop numerical techniques to rotate Wilson loops by arbitrary angles in lattice gauge theories close to the continuum. As a first application, we compute the glueball spectrum of the SU(2) gauge theory in 2+1 dimensions for both parities and for spins ranging from 0 up to 4 inclusive. We measure glueball angular wave functions directly, decomposing them in Fourier modes and extrapolating the Fourier coefficients to the continuum. This allows a reliable labelling of the continuum states and gives insight into the way rotation symmetry is recovered. As one of our results, we demonstrate that the D=2+1 SU(2) glueball conventionally labelled as J P =0 - is in fact 4 - and that the lightest "J=1" state has, in fact, spin 3. © 2003 Elsevier Science B.V. All rights reserved.

Abstract:

We report on our ongoing investigation of the deconfining phase transition in SU(4) and SU(6) gauge theories. We calculate the critical couplings while taking care to avoid the influence of a nearby bulk phase transition. We determine the latent heat of the phase transition and investigate the order and the strength of the transition at large Nc. We also report on our determination of the critical temperature expressed in units of the string tension in the large. Nc limit.