The deconfinement transition in SU(N) gauge theories
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 545:1-2 (2002) 197-206
Abstract:
We investigate the properties of the deconfinement transition in SU(4) and SU(6) gauge theories. We find that it is a 'normal' first order transition in both cases, from which we conclude that the transition is first order in the N → ∞ limit. Comparing our preliminary estimates of the continuum values of Tc/√σ with existing values for SU(2) and SU(3) demonstrates a weak dependence on N for all values of N. © 2002 Published by Elsevier Science B.V.Topology and confinement in SU(N) gauge theories
Nuclear Physics B - Proceedings Supplements 106-107 (2002) 685-687
Abstract:
The large N limit of SU(N) gauge theories in 3+1 dimensions is investigated on the lattice by extrapolating results obtained for 2 ≤ N ≤ 5. A numerical determination of the masses of the lowest-lying glueball states and of the topological susceptibility in the limit N → ∞ is provided. Ratios of the tensions of stable κ-strings over the tension of the fundamental string are investigated in various regimes and the results are compared with expectations based on several scenarios - in particular MQCD and Casimir scaling. While not conclusive at zero temperature in D=3+1, in the other cases investigated our data seem to favour the latter.Effects of nonperturbatively improved dynamical fermions in QCD at fixed lattice spacing
Physical Review D 65:5 (2002)
Abstract:
We present results for the static interquark potential, lightest glueballs, light hadron spectrum, and topological susceptibility using a nonperturbatively improved action on a 163×32 lattice at a set of values of the bare gauge coupling and bare dynamical quark mass chosen to keep the lattice size fixed in physical units (∼1.7 fm). By comparing these measurements with a matched quenched ensemble, we study the effects due to two degenerate flavors of dynamical quarks. With the greater control over residual lattice spacing effects which these methods afford, we find some evidence of charge screening and some minor effects on the light hadron spectrum over the range of quark masses studied (MPS/Mv ≥ 0.58, where PS denotes pseudoscalar and V denotes vector). More substantial differences between quenched and unquenched simulations are observed in measurements of topological quantities. ©2002 The American Physical Society.Glueball spectrum in O(a)-improved lattice QCD
Physical Review D 65:3 (2002)
Abstract:
We calculate the light "glueball" mass spectrum in N f=2 lattice QCD using a fermion action that is nonperturbatively O(a) improved. We work at lattice spacings a∼0.1 fm and with quark masses that range down to about one-half the strange quark mass. We find the statistical errors to be moderate and under control on relatively small ensembles. We compare our mass spectrum to that of quenched QCD at the same value of a. While the tensor mass is the same (within errors), the scalar mass is significantly smaller in the dynamical lattice theory, by a factor of ∼0.84±0.03. We discuss what the observed mq dependence of this suppression tells us about the dynamics of glueballs in QCD. We also calculate the masses of flux tubes that wind around the spatial torus, and extract the string tension from these. As we decrease the quark mass we see a small but growing vacuum expectation value for the corresponding flux tube operators. This provides clear evidence for "string breaking" and for the (expected) breaking of the associated gauge center symmetry by sea quarks. © 2002 The American Physical Society.SU(N) gauge theories in 2 + 1 dimensions: Further results
Physical Review D 66:9 (2002)