Vortices versus monopoles in color confinement

We construct the creation operator of a vortex for SU(2) pure gauge theory using the methods developed for monopoles. We interpret its vacuum expectation value as a disorder parameter for the deconfinement phase transition and find that it behaves in the vacuum in a similar way to monopoles. Results are extrapolated to the thermodynamical limit using finite-size scaling.Comment: Talk presented at Lattice2000 (Topology and Vacuum), 4 page

The abelian projection revisited

Abelian projection is reanalysed in the frame of the SU(N) Higgs model. The extension to QCD is discussed. It is shown that dual superconductivity of the vacuum is an intrinsic property independent of the choice of the abelian projection.Comment: 3 pages, 1 figure, Lattice2003(topology

Semi-analytic calculation of the monopole order parameter in QCD

The monopole order parameter of QCD is computed in terms of gauge invariant field strength correlators. Both quantities are partially known from numerical simulations on the lattice. A new insight results on the structure of the confining vacuum.Comment: Talk presented at QCD06, Montpellier 3-7 July 2006. To appear in the proceeding

't Hooft tensor for generic gauge group

We study monopoles in gauge theories with generic gauge group. Magnetic charges are in one-to-one correspondence with the second homotopy classes at spatial infinity (${\Pi}_2$), which are therefore identified by the 't Hooft tensor. We determine the 't Hooft tensor in the general case. These issues are relevant to the understanding of Color Confinement.Comment: 5 pages. Contribution to the Conference QCD08, Montpellier 7-12 July 2008 To appear in the proceeding

Chiral transition and deconfinement in N_f = 2 QCD

The transition is studied by means of a disorder parameter detecting condensation of magnetic monopoles in the vacuum. The deconfining transition is found to coincide with the chiral transition and the susceptibility \rho, related to the disorder parameter, is consistent with a first order phase transition.Comment: 3 pages, 2 figures. Poster presented at Lattice2004(topology), Fermilab, June 21-26, 200

Dual Superconductivity and Chiral Symmetry in Full QCD

A disorder parameter detecting dual superconductivity of the vacuum is measured across the chiral phase transition in full QCD with two flavours of dynamical staggered fermions. The observed behaviour is similar to the quenched case.Comment: Lattice2001(confinement) proceedings, 3 pages, 2 eps figure

Dual superconducting properties of the QCD vacuum

A consistent description of the confining QCD vacuum as a dual superconductor requires a determination of fundamental parameters such as the superconductor correlation length $\xi$ and the field penetration depth $\lambda$, which determine whether the superconductor is of type I or type II. We illustrate preliminary results of a lattice determination of $\xi$ for the case of pure Yang-Mills with two colors, obtained by measuring the temporal correlator of a disorder parameter detecting dual superconductivity.Comment: 4 pages, 2 figures, talk presented at QCD05 (Montpellier) 4-9 July 200

Confinement in QCD

The guiding lines of lattice investigations on colour confinement are reviewed, together with recent results.Comment: 7 pages,3 figures, Plenary talk at PANIC'99,10-16 June 1999,Uppsal

A Possible Universal Treatment of the Field Strength Correlator in the Abelian-Projected SU(2)-Theory

An integral relation between two functions parametrizing the bilocal field strength correlator within the Stochastic Vacuum Model is obtained in the effective Abelian-projected SU(2)-theory. This relation is independent of the concrete properties of the ensemble of vortex loops, which are present in the theory under study. By virtue of the lattice result stating that the infrared asymptotic behaviours of these functions should have the same functional form, the obtained relation enables one to find these behaviours, as well as the infrared asymptotics of the bilocal correlator of densities of the vortex loops. Those turn out to be exponentials, decreasing at the inverse mass of the dual vector boson, times certain polynomials in the inverse integer powers of the distance. This result agrees with the general predictions and the existing lattice data better than the results of previous calculations, where these powers were found to be half-integer ones.Comment: 9 pages, LaTeX2e, no figures, new discussions of the obtained results are added, to appear in Phys. Lett.

Monopole condensation in the ground state of gauge theories: a disorder parameter

We construct a disorder parameter for dual superconductivity of the ground state of $U(1)$ gauge theory.Comment: 3 pages, contribution to the Lattice '94 conference, shell archive containing uuencoded LATEX file + 2 figure