Glueballs and k-strings in SU(N) gauge theories: calculations with improved operators
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 in[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 = infty, obtaining results compatible with earlier work. We show that the N = infty factorisation of the euclidean correlators that are used in such mass calculations does not make the masses any less calculable at large N.
- Publication:
-
Journal of High Energy Physics
- Pub Date:
- June 2004
- DOI:
- 10.1088/1126-6708/2004/06/012
- arXiv:
- arXiv:hep-lat/0404008
- Bibcode:
- 2004JHEP...06..012L
- Keywords:
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- 1/N Expansion Confinement Lattice Gauge Field Theories;
- High Energy Physics - Lattice
- E-Print:
- 49 pages, 15 figures