Particle theory

Abstract:

We calculate glueball masses and the string tension on lattices as large as 204 and at couplings as small as β= 6 g2=6.2. To be able to do so we construct wave-functionals that maintain a good overlap with the long-distance physics as the lattice spacing is made small. Our calculations strongly indicate that the lightest glueball is the 0++ and that the next highest levels are a nearly degenerate 2++ and 0-+ at roughly 1.6m[0++]. In addition there is a 1+- just below 2m[0++]. The mass of the scalar is about 3.5 times the square root of the string tension. We find that this ratio is consistent with being independent of β for β≥5.9 (in contrast to its strong variation at lower β) and that this appears tobe so at a statistically significant level. The ratio of the 2++ and 0++ glueball masses is also consistent with being independent of β. © 1988.

Abstract:

We extend previous calculations of the zero-temperature topological susceptibility, χt, to larger lattices (up to 204) and smaller lattice spacings (up to β=6.2). Using a new technique we are able to achieve a precise control of finite size corrections. We confirm, with much greater systematic and statistical precision, that the dimensionless ratio χt/K2 is independent of β for β≥5.7. This enables us to extract χt in physical units and we find χt=(179±4 MeV)4 - statistical error only - which is in striking agreement with the Witten-Veneziano calculation. We also investigate the previously observed fact that χt is suppressed as the temperature is raised through the deconfining transition. We find that χt is in fact discontinuous at the phase transition and that its temperature dependence is otherwise weak as long as it remains in a single well-defined phase. © 1988.

Abstract:

We describe methods for constructing lattice operators that maintain their overlap onto the desired long distance physics as the lattice spacing is decreased. © 1988.