Glueballs and k-strings in SU(N) gauge theories: Calculations with improved operators
Journal of High Energy Physics 8:6 (2004) 283-326
Abstract:
We test a variety of blocking and smearing algorithms for constructing glueball and string wave-functionals, and find some with much improved overlaps onto the lightest states. We use these algorithms to obtain improved results on the tensions of k-strings in SU(4), SU(6), and SU(8) gauge theories. We emphasise the major systematic errors that still need to be controlled in calculations of heavier k-strings, and perform calculations in SU(4) on an anisotropic lattice in a bid to minimise one of these. All these results point to the k-string tensions lying part-way between the 'MQCD' and 'Casimir Scaling' conjectures, with the power in 1/N of the leading correction lying ∈ [1,2]. We also obtain some evidence for the presence of quasi-stable strings in calculations that do not use sources, and observe some near-degeneracies between (excited) strings in different representations. We also calculate the lightest glueball masses for N = 2,..., 8, and extrapolate to N = ∞, obtaining results compatible with earlier work. We show that the N = ∞ factorisation of the euclidean correlators that are used in such mass calculations does not make the masses any less calculable at large N. © SISSA/ISAS 2004.Glueballs and the pomeron
NUCL PHYS B-PROC SUP 129-30 (2004) 200-202
Abstract:
We present our latest results on the glueball spectrum of SU(N) gauge theories in 2+1 dimensions for spins ranging from 0 to 6 inclusive, as well as preliminary results for SU(3) in 3+1 dimensions. Simple glueball models and the relation of the even-spin spectrum to the 'Pomeron' are discussed.THE HIGH TEMPERATURE PHASE TRANSITION IN SU(N) GAUGE THEORIES
Journal of High Energy Physics (2004)
Chiral symmetry breaking and topology for all N
Nuclear Physics B - Proceedings Supplements 129-130 (2004) 489-491
Abstract:
We investigate spontaneous chiral symmetry breaking in SU(N) gauge theories at large N using overlap fermions. The exact zero modes and the low-lying modes of the Dirac operator provide the tools to gain insight into the interplay between chiral symmetry breaking and topology. We find that topology indeed drives chiral symmetry breaking at N = 3 as well as at large N. By comparing the results on various volumes and at different lattice spacings we are able to show that our conclusions are not affected by finite volume effects and also hold in the continuum limit. We then address the question whether the topology can be usefully described in terms of instantons. © 2004 Elsevier B.V. All rights reserved.SU (N) gauge theories near Tc
Nuclear Physics B - Proceedings Supplements 129-130 (2004) 569-571