Particle theory

Abstract:

We investigate the crumpling transition on crystalline random surfaces with extrinsic curvature on lattices up to $64^2$. Our data are consistent with a second order phase transition and we find correlation length critical exponent $\nu=0.89\pm 0.07$. The specific heat exponent, $\alpha=0.2\pm 0.15$, is in much better agreement with hyperscaling than hitherto. The long distance behaviour of tangent-tangent correlation functions confirms that the so-called Hausdorff dimension is $d_H=\infty$ throughout the crumpled phase.

Abstract:

The U(1) Villain model is simulated in three and four dimensions. We locate monopoles using both the conventional DeGrand-Toussaint prescription and the exact prescription as provided by the model itself. The two monopole gases thus obtained are compared, in particular with respect to their confining and percolation properties. In this way we investigate to how strong a coupling the conventional definition of lattice monopoles remains reliable. We show that in the interesting range of "intermediate" couplings (β0.3) the difference between the two monopole gases can be very well reproduced by a random distribution of dipoles (which possesses trivial long-distance properties). This suggests that the DeGrand-Toussaint prescription can indeed be meaningfully used in studies of, for example, the U(1) phase transition and the monopole mechanism for non-Abelian confinement. © 1993 The American Physical Society.

Abstract:

The HTMCGC collaboration has been simulating lattice QCD with two light staggered quarks with masses mq = 0.0125 and also mq = 0.00625 on a 163 × 8 lattice. We have been studying the behaviour of the transition from hadronic matter to a quark-gluon plasma and the properties of that plasma. We have been measuring entropy densities, Debye and hadronic screening lengths, the spacial string tension and topological susceptibility in addition to the standard order parameters. The HEMCGC collaboration has simulated lattice QCD with two light staggered quarks, mq = 0.025 and mq = 0.010 on a 163 × 32 lattice. We have measured the glueball spectrum and topological susceptibilities for these runs. © 1993.