Particle theory

Abstract:

We use fuzzy Wilson loops on lattices of different spatial size to study the glueball spectrum. Accurate results on 0+ and 2+ states for SU(2) of colour are reported here. © 1987.

Abstract:

We calculate 0+ and 2+ correlation functions using an improved method. On small physical volumes we reproduce the result, m(0+)≈m(2+), recently obtained by other methods. However, we also obtain evidence that for larger physical volumes the 2+ is heavier than the 0+: m(2+) m(0+)≈ 5 3. © 1987.

Abstract:

We present a simple iterative method for obtaining glueball wave functionals of the appropriate physical size as one decreases the lattice spacing. We test the method in SU (2) for 2.1 ≤ β ≤ 2.5 and find a gain in computer time over previous methods, that can be several orders of magnitude. The method appears to make possible reliable, large lattice calculations of excited glueball masses and significantly extends the range of bare couplings where reliable glueball calculations can be performed. © 1987.

Abstract:

We measure the topological charge density of the (Monte Carlo generated) SU(3) vacuum. Our algorithm involves first smoothening the generated configurations in a way that conserves the total charge in the continuum limit. We work in a range of couplings 5.6 ≤ β ≡ 6/g2 ≤ 6.0 and on lattice sizes up to 164. We find that the topological susceptibility scales like the string tension (within errors). This allows us to extract a value in physical units, Xt 1 4 = 191 ± 16 MeV, in good agreement with the Witten-Veneziano mass formula. We also show how Xt is strongly suppressed as the temperature is increased through the deconfining transition, so that the UA(1) symmetry is effectively restored in the deconfined phase. Our results leave open the possibility that Xt is an order parameter for this transition. We carefully monitor finite size effects and perform a variety of calculations - reproducibility, stability under Monte Carlo, distribution of core sizes, etc. - which give us a direct insight into the approach to continuum topology. © 1987.