Leonardo Cosmai

Dual superconductivity in the SU(2) pure gauge vacuum: A lattice study.

We investigate the dual superconductivity hypothesis in pure SU(2) lattice gauge theory. We focus on the dual Meissner effect by analyzing the distribution of the color fields due to a static quark-antiquark pair. We find evidence of the dual Meissner effect both in the maximally Abelian gauge and without gauge fixing. We measure the London penetration length. Our results suggest that the London penetration length is a physical gauge-invariant quantity. We put out a simple relation between the penetration length and the square root of the string tension. We find that our estimation is quite close to the extrapolated continuum limit available in the literature. A remarkable consequence of our study is that an effective Abelian theory can account for the long range properties of the SU(2) confining vacuum.

Analytic continuation from imaginary to real chemical potential in two-color QCD

The method of analytic continuation from imaginary to real chemical potential is one of the most powerful tools to circumvent the sign problem in lattice QCD. Here we test this method in a theory, two-color QCD, which is free from the sign problem. We find that the method gives reliable results, within appropriate ranges of the chemical potential, and that a considerable improvement can be achieved if suitable functions are used to interpolate data with imaginary chemical potential.

Abelian chromomagnetic fields and confinement

We study vacuum dynamics of SU(3) lattice gauge theory at finite temperature. The SU(3) vacuum is probed by means of an external constant abelian chromomagnetic field. We find that by increasing the strength of the applied external field the deconfinement temperature decreases towards zero. This means that strong enough abelian chromomagnetic fields destroy confinement of color. We discuss some consequences of this phenomenon on confinement and quark stars.

Analytic continuation of the critical line: Suggestions for QCD

We perform a numerical study of the systematic effects involved in the determination of the critical line at real baryonic chemical potential by analytic continuation from results obtained at imaginary chemical potentials. We present results obtained in theories free of the sign problem, such as two-color QCD with finite baryonic density and three-color QCD with finite isospin chemical potential, and comment on general features which could be relevant also to the continuation of the critical line in real QCD at finite baryonic density.

Flux tubes in the SU(3) vacuum: London penetration depth and coherence length

Within the dual superconductor scenario for the QCD confining vacuum, the chromoelectric field generated by a static

Abelian monopole and vortex condensation in lattice gauge theories

q\overline{q}

Critical line of 2 + 1 flavor QCD: Toward the continuum limit

pair can be fitted by a function derived, by dual analogy, from a simple variational model for the magnitude of the normalized order parameter of an isolated Abrikosov vortex. Previous results for the SU(3) vacuum are revisited, but here the transverse chromoelectric field is measured by means of the connected correlator of two Polyakov loops and, in order to reduce noise, the smearing procedure is used instead of cooling. The penetration and coherence lengths of the flux tube are then extracted from the fit and compared with previous results.

Chromoelectric flux tubes and coherence length in QCD

We study abelian monopole and vortex condensation in lattice pure gauge theories. Condensation is detected by means of a disorder parameter defined in terms of a gauge-invariant effective action introduced using the lattice Schrodinger functional. Dirac monopoles condense in the confined phase of U(1) lattice gauge theory. Abelian monopoles and abelian vortices condense in the confined phase of SU(2) and SU(3) lattice gauge theories.

Critical line from imaginary to real baryonic chemical potentials in two-color QCD

We determine the continuum limit of the curvature of the pseudocritical line of QCD with

The deconfining phase transition in full QCD with two dynamical flavors

{n}_{f}=2+1