Spinorial flux tubes in SO(N) gauge theories in 2+1 dimensions

We investigate whether one can observe in SO(3) and SO(4) (lattice) gauge theories the presence of spinorial flux tubes, i.e. ones that correspond to the fundamental representation of SU(2); and similarly for SO(6) and SU(4). We do so by calculating the finite volume dependence of the JP=2+ glueball in 2+1 dimensions, using lattice simulations. We show how this provides strong evidence that these SO(N) gauge theories contain states that are composed of pairs of (conjugate) winding spinorial flux tubes, i.e. ones that are in the (anti)fundamental of the corresponding SU(N') gauge theories. Moreover, these two flux tubes can be arbitrarily far apart. This is so despite the fact that the fields that are available in the SO(N) lattice field theories do not appear to allow us to construct operators that project onto single spinorial flux tubes.Comment: 23 pages, 8 figures, reference to recent relevant paper, version to be submitted to journa

Large-N gauge theories: lattice perspectives and conjectures

I summarise what recent lattice calculations tell us about the large-N limit of SU(N) gauge theories in 3+1 dimensions. The focus is on confinement, how close SU(oo) is to SU(3), new stable strings at larger N, deconfinement, topology and theta-vacua. I discuss the effective string theory description, as well as master fields, space-time reduction and non-analyticity.Comment: 18 pages. Based on talks at `Large N QCD', ECT July 2004, `Hadrons and Strings', ECT July 2004, `QCD and String Theory', KITP UCSB Sept 2004. To appear in `Large N QCD' Proceeding

Large Nc physics from the lattice

I summarise what lattice methods can contribute to our understanding of the phenomenology of QCD at large Nc and describe some recent work on the physics of SU(Nc) gauge theories. These non-perturbative calculations show that there is indeed a smooth Nc -> infinity limit and that it is achieved by keeping g.g.Nc fixed, confirming the usual diagrammatic analysis. The lattice calculations support the crucial assumption that the theory remains linearly confining at large Nc. Moreover we see explicitly that Nc=3 is `close to' Nc=infinity for many physical quantities. We comment on the fate of topology and the deconfining transition at large Nc. We find that multiple confining strings are strongly bound. The string tensions, K(k), of these k-strings are close to the M(-theory)QCD-inspired conjecture as well as to `Casimir scaling' with the most accurate recent calculations favouring the former. We point out that closed k-strings provide a natural way for non-perturbative effects to introduce O(1/Nc) corrections into the pure gauge theory, in contradiction to the conventional diagrammatic expectation.Comment: 10 pages. Invited talk, The Phenomenology of Large-Nc QCD, to be published Proceedings of the Institute of Nuclear Theor

Topology in QCD

I review recent (and some not so recent) results on the topological susceptibility (with and without fermions), the eta-prime mass, topology and chiral symmetry breaking, vacuum topological structure, and the possible role of instantons in confinement.Comment: LATTICE99(plenary), 5 page

Glueballs and the Pomeron

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.Comment: LAT03 proceedings (spectrum), 3 pages, 3 figures, talk by H.Meye

Universality, Scaling and Topology with a Modified Lattice Action

We examined the effect of a complete suppression of a lattice artifact, the negative plaquettes, on physical quantities, such as the critical temperature, the string tension, the topological charge, glueball masses, and their ratios.Comment: 3 pages, self unpacking uuencoded PostScript file, contribution to conference LATTICE '9