4,011 research outputs found
Condensation of vortices and disorder parameter in 3d Heisenberg model
The 3d Heisenberg model is studied from a dual point of view. It is shown
that the disordered phase corresponds to condensation of vortices in the
vacuum, and the critical indices are computed from the corresponding disorder
parameter.Comment: LATTICE98(spin
Confinement and monopole condensation: some properties of the disorder parameter
We demonstrate that the disorder parameter to detect dual
superconductivity in the confining phase of QCD is the v.e.v. of a magnetically
charged, Dirac like, gauge invariant operator . We also show that the
abelian projection on the lattice is determined up to terms O(a^2) (a = lattice
spacing).Comment: Lattice2001(confinement) proceeding
Theory of color confinement: state of the art
The existing evidence for dual superconductivity as mechanism of color
confinement is reviewed. We also discuss what is known on the dual excitations,
which produce confinement by condensation, and what are the open problem
Magnetic charge superselection in the deconfined phase of Yang-Mills theory
The vacuum expectation value of an operator carrying magnetic charge is
studied numerically for temperatures above the deconfinement temperature in
SU(2) and SU(3) gauge theory. By analyzing its finite size behaviour, this is
found to be exactly zero in the thermodynamical limit for any T > T_c whenever
the magnetic charge of the operator is different from zero. These results show
that magnetic charge is superselected in the hot phase of quenched QCD.Comment: 4 pages, 6 figures, revtex
A dual view of the 3d Heisenberg model and the abelian projection
The Heisenberg model in 3d is studied from a dual point of view. It is shown
that it can have vortex configurations, carrying a conserved charge(U(1)
symmetry). Vortices condens in the disordered phase. A disorder parameter
\leftangle\mu\rightangle is defined dual to the magnetization \leftangle\vec
n\rightangle, which signals condensation of vortices, i.e. spontaneous
breaking of the dual U(1) symmetry. This study sheds light on the procedure
known as abelian projection in non abelian gauge theories.Comment: LateX, 15 pages, 3 figure
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
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
Gauge-invariant quark-antiquark nonlocal condensates in lattice QCD
We study, by numerical simulations on a lattice, the behaviour of the
gauge-invariant quark-antiquark nonlocal condensates in the QCD vacuum with
dynamical fermions. A determination is also done in the quenched approximation
and the results are compared with the full-QCD case. The fermionic correlation
length is extracted and compared with the analogous gluonic quantity.Comment: 14 pages, LaTeX file, + 6 PS figure
A test of first order scaling in Nf=2 QCD
We complete our analysis of Nf=2 QCD based on the lattice staggered fermion
formulation. Using a series of Monte Carlo simulations at fixed (amq*Ls^yh) one
is able to test the universality class with given critical exponent yh. This
strategy has been used to test the O(4) universality class and it has been
presented at the previous Lattice conferences. No agreement was found with
simulations in the mass range amq=[0.01335,0.15] using lattices with Ls=16 up
to 32 and Lt=4. With the same strategy, we now investigate the possibility of a
first order transition using a new set of Monte Carlo data corresponding to
yh=3 in the same mass and volume range as the one used for O(4). A substantial
agreement is observed both in the specific heat scaling and in the scaling of
the chiral condensate, while the chiral susceptibilities still presents visible
deviation from scaling in the mass range explored.Comment: 5 pages, 6 figures, Presented at the XXV International Symposium on
Lattice Field Theory, July 30 - August 4 2007, Regensburg, German
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