18 research outputs found
Confining properties of 2-color QCD at finite density
We study the confining properties of QCD with two colors across the finite
density phase transition. A disorder parameter detecting dual superconductivity
of the QCD vacuum is used as a probe for the confinement/deconfinement phase
transition.Comment: 7 pages, 3 figures, talk presented at Lattice 2006 (High Temperature
and Density
Magnetic monopoles in high temperature QCD
We study the density and spatial distribution of thermal Abelian monopoles in
the deconfined phase of SU(2) pure gauge theory: they display non-trivial
interactions with a well defined continuum limit. The Maximal Abelian Gauge
(MAG) has been chosen to perform the Abelian projection. Questions related to
the choice of the Abelian projection, as well as possible directions for future
studies, are discussed.Comment: 5 pages, 2 figures, contribution to the 8th Conference on Quark
Confinement and the Hadron Spectrum, September 1-6, 2008, Mainz, German
Thermal monopoles and selfdual dyons in the Quark-Gluon Plasma
We perform a numerical study of the excess of non-abelian gauge invariant
gluonic action around thermal abelian monopoles which populate the deconfined
phase of Yang-Mills theories. Our results show that the excess of magnetic
action is close to that of the electric one, so that thermal abelian monopoles
may be associated with physical objects carrying both electric and magnetic
charge, i.e. dyons. Thus, the quark gluon plasma is likely to be populated by
selfdual dyons, which may manifest themselves in the heavy-ion collisions via
the chiral magnetic effect. Thermodynamically, thermal monopoles provide a
negative contribution to the pressure of the system.Comment: 9 pages, 4 figures, RevTeX 4.
On the phase diagram of the Higgs SU(2) model
The Higgs SU(2) model with fixed Higgs length is usually believed to have two
different phases at high gauge coupling (\beta), separated by a line of first
order transitions but not distinuguished by any typical symmetry associated
with a local order parameter, as first proved by Fradkin and Shenker. We show
that in regions of the parameter space where it is usually supposed to be a
first order phase transition only a smooth crossover is in fact present.Comment: 6 pages, 6 figures. Talk presented at The XXVI International
Symposium on Lattice Field Theory, July 14 - 19, 2008 - Williamsburg,
Virginia, US
Confining Properties of Two-color QCD at Finite Density
We study the confining properties of QCD with two colors across the finite density phase transition. A disorder parameter detecting dual superconductivity of the QCD vacuum is used as a probe for the confinement/deconfinement phase transition
Dual superconductivity and vacuum properties in Yang--Mills theories
We address, within the dual superconductivity model for color confinement,
the question whether the Yang-Mills vacuum behaves as a superconductor of type
I or type II. In order to do that we compare, for the theory with gauge group
SU(2), the determination of the field penetration depth with that of
the superconductor correlation length . The latter is obtained by
measuring the temporal correlator of a disorder parameter developed by the Pisa
group to detect dual superconductivity. The comparison places the vacuum close
to the border between type I and type II and marginally on the type II side. We
also check our results against the study of directly measurable effects such as
the interaction between two parallel flux tubes, obtaining consistent
indications for a weak repulsive behaviour. Future strategies to improve our
investigation are discussed.Comment: 23 pages, 15 figures. Simulations on finer lattices and with
different monopole charges added. Final version to be published in Nuclear
Physics
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 and the field penetration depth , which
determine whether the superconductor is of type I or type II. We illustrate
preliminary results of a lattice determination of 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
Magnetic Component of Quark-Gluon Plasma
We describe recent developments of the "magnetic scenario" of sQGP. We show
that at there is a dense plasma of monopoles, capable of
supporting metastable flux tubes. Their existence allows to quantitatively
explained the non-trivial -dependence of the static potential
energy calculated on the lattice. By molecular dynamics simulation we derived
transport properties (shear viscosity and diffusion constant) and showed that
the best liquid is given by most symmetric plasma, with 50%-50% of electric and
magnetic charges. The results are close to those of the ``perfect liquid''
observed at RHIC.Comment: Contribution to the 20th International Conference on Nucleus Nucleus
Collisions (Quark Matter 2008
Quark-Gluon Plasma - New Frontiers
As implied by organizers, this talk is not a conference summary but rather an
outline of progress/challenges/``frontiers'' of the theory. Some fundamental
questions addressed are:
Why is sQGP such a good liquid? Do we understand (de)confinement and what do
we know about ``magnetic'' objects creating it? Can we understand the AdS/CFT
predictions, from the gauge theory side? Can they be tested experimentally? Can
AdS/CFT duality help us understand rapid equilibration/entropy production? Can
we work out a complete dynamical ``gravity dual'' to heavy ion collisions?Comment: final talk at Quark Matter 2008, Jaipur, India, Feb.200
Magnetic monopoles in the high temperature phase of Yang-Mills theories.
We investigate the properties of thermal Abelian magnetic monopoles in the high temperature phase of YangâMills theories, following a recent proposal for their identification on lattice configurations. The study is done for SU(2) pure gauge theory, for temperatures going up to about 10 times the deconfining temperature and using the Maximal Abelian gauge to perform the Abelian projection. We find that the monopole density has a well defined continuum limit. Its temperature dependence disagrees with a free particle gas prediction and is instead well described by a T^3/(log(T /Î))^a behaviour in all the explored range, with α ⌠2 and Π⌠100 MeV. Also the study of spatial correlations of thermal monopoles shows the presence of non-trivial interactions among them. Finally, we discuss the gauge dependence of our results, showing that it is significant and that, even within the Maximal Abelian gauge, Gribov copy effects are
important