paper

String models of glueballs and the spectrum of SU(N) gauge theories in 2+1 dimensions

arXiv:hep-ph/0012287 · doi:10.1103/PhysRevD.66.036006

Abstract

The spectrum of glueballs in 2+1 dimensions is calculated within an extended class of Isgur-Paton flux tube models and is compared to lattice calculations of the low-lying SU(N) glueball mass spectra. Our modifications of the model include a string curvature term and different ways of dealing with the flux tube width. We find that the generic model is remarkably successful at reproducing the positive charge conjugation, C=+, sector of the spectrum. The only large (and robust) discrepancy involves the 0-+ state. This raises the interesting possibility that the lattice spin identification is mistaken and that this state is in fact 4-+. In addition, the Isgur-Paton model does not incorporate any mechanism for splitting C=+ from C=- (in contrast to the case in 3+1 dimensions), while the `observed' spectrum shows a substantial splitting. We explore several modifications of the model in an attempt to incorporate this physics in a natural way. At the qualitative level we find that this constrains our choice to a picture in which the C=+/- splitting is driven by mixing with new states built on closed loops of adjoint flux. However a detailed numerical comparison suggests that a model incorporating an additional direct mixing between loops of opposite orientation is likely to work better; and that, in any case, a non-zero curvature term will be required. We also point out that a characteristic of any string model of glueballs is that the SU(N=infinity) mass spectrum will consist of multiple towers of states that are scaled up copies of each other. To test this will require a lattice mass spectrum that extends to somewhat larger masses than currently available.

29 pages. Compressed version for publication. See V.1 for useful extra details

References in corpus (18)

Cited by in corpus (25)