Publications (35)1.08 Total impact
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ABSTRACT: The transverse profile of the chromoelectric flux tubes in SU(2) and SU(3)
pure gauge theories is analyzed by a simple variational ansatz using a strict
analogy with ordinary superconductivity. Our method allows to extract the
penetration length and the coherence length of the flux tube.
08/2012;
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ABSTRACT: We investigate planar quantum electrodynamics (QED) with two degenerate
staggered fermions in an external magnetic field on the lattice. We argue that
in external magnetic fields there is dynamical generation of mass for
two-dimensional massless Dirac fermions in the weak-coupling region. We
extrapolate our lattice results to the quantum Hall effect in graphene.
04/2012;
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ABSTRACT: We analyze the distribution of the chromoelectric field generated by a static
quark-antiquark pair in the SU(3) vacuum. We find that the transverse profile
of the flux tube resembles the dual version of the Abrikosov vortex field
distribution and give an estimate of the London penetration length in the
confined vacuum.
09/2011;
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ABSTRACT: We investigate planar Quantum ElectroDynamics (QED) with two degenerate
staggered fermions in an external magnetic field on the lattice. Our
preliminary results indicate that in external magnetic fields there is
dynamical generation of mass for two-dimensional massless Dirac fermions in the
weak coupling region. We comment on possible implications to the quantum Hall
effect in graphene.
09/2011;
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ABSTRACT: We analyze the distribution of the chromoelectric field generated by a static
quark-antiquark pair in the SU(3) vacuum and revisit previous results for
SU(2). We find that the transverse profile of the flux tube resembles the dual
version of the Abrikosov vortex field distribution. We give an estimate of the
London penetration length of the chromoelectric field in the confined vacuum.
We also speculate on the value of the ratio between the penetration lengths for
SU(2) and SU(3) gauge theories.
11/2010;
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ABSTRACT: We revisit the determination of the pseudo-critical line of QCD with four degenerate quarks at non-zero temperature and baryon density by the method of analytic continuation. We determine the pseudo-critical couplings at imaginary chemical potentials by high-statistics Monte Carlo simulations and reveal deviations from the simple quadratic dependence on the chemical potential visible in earlier works on the same subject. Finally, we discuss the implications of our findings for the shape of the pseudo-critical line at real chemical potential, comparing different possible extrapolations. Comment: 8 pages, 8 figures, 2 tables
04/2010;
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ABSTRACT: We perform a numerical study of the systematic effects involved in the determination of the critical line at real baryon chemical potential by analytic continuation from results obtained at imaginary chemical potentials. We present results obtained in a theory free of the sign problem, 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 baryon density. Comment: 7 pages, 3 figures, Contribution to The XXVII International Symposium on Lattice Field Theory, Beijing, July 25-31, 2009
01/2010;
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ABSTRACT: We discuss the triviality and spontaneous symmetry breaking scenario where
the Higgs boson without self-interaction coexists with spontaneous symmetry
breaking. We argue that non perturbative lattice investigations support this
scenario. Moreover, from lattice simulations we predict that the Higgs boson is
rather heavy. We estimate the Higgs boson mass $m_H = 754 \pm 20
{\text{(stat)}} \pm 20 {\text{(syst)}} {\text{GeV}}$ and the Higgs total width
$\Gamma(H) \simeq 340 {\text{GeV}}$.
11/2009;
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ABSTRACT: 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. Comment: 12 pages, 13 figures, 7 tables (revised version accepted by Phys. Rev. D80, 034501(2009))
05/2009;
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ABSTRACT: The method of analytic continuation from imaginary to real chemical potentials $\mu$ is one of the few available techniques to study QCD at finite temperature and baryon density. One of its most appealing applications is the determination of the critical line for small $\mu$: we perform a direct test of the validity of the method in this case by studying two-color QCD, where the sign problem is absent. The (pseudo)critical line is found to be analytic around $\mu^2 = 0$, but a very large precision would be needed at imaginary $\mu$ to correctly predict the location of the critical line at real $\mu$.
01/2008;
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ABSTRACT: We determine the pseudo-critical line in the temperature - chemical potential plane of 2-color QCD by direct Monte Carlo simulations and by analytic continuation from imaginary chemical potential.
11/2007;
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ABSTRACT: We present some up-to-date results on QCD phase transition in a chromomagnetic constant background field and in an abelian monopole background field. Our results indicate that the QCD critical temperature is not modified by a monopole background field, whilst it is modified by a constant chromomagnetic field. We improve our earlier estimate of the QCD critical parameters in a chromomagnetic background field by performing lattice simulations with weaker fields.
11/2007;
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ABSTRACT: We investigate the phase transition in full QCD with two flavors of staggered fermions in presence of a constant abelian chromomagnetic field. We find that the critical temperature depends on the strength of the chromomagnetic field and that the deconfined phase extends to very low temperatures for strong enough fields. As in the case of zero external field, a single transition is detected, within statistical uncertainties, where both deconfinement and chiral symmetry restoration take place. We also find that the chiral condensate increases with the strength of the chromomagnetic field.
08/2007;
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ABSTRACT: 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, 2-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. Comment: 28 pages, 16 figures, references added, minor changes in Sections 3.3 and 4. Final version to appear in JHEP
12/2006;
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ABSTRACT: We investigate the deconfining phase transition in full QCD with two flavors of staggered fermions in presence of a constant abelian chromomagnetic field. We find that the deconfinement temperature decreases and eventually goes to zero by increasing the strength of the chromomagnetic field. Moreover our results suggest that the chiral transition coincides with the deconfinement transition and therefore even the chiral critical temperature depends on the applied chromomagnetic field. We also find that the chiral condensate increases with the strength of the chromomagnetic field.
11/2006;
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ABSTRACT: The QCD vacuum can be studied using external fields. We report here results respectively obtained probing the lattice QCD vacuum by means of an abelian monopole field and of an abelian chromomagnetic field
03/2006;
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ABSTRACT: We compare vacuum dynamics of abelian versus non abelian lattice gauge theories in presence of external fields. We find that the deconfinement temperature of non abelian theories depends on the strength of a constant abelian chromomagnetic field end eventually goes to zero. On the contrary such an effect is not shared by abelian theories. We argue on the relevance of this result to understand the QCD vacuum. Comment: Poster presented at Lattice2005 (Topology and Confinement), Dublin, July 25-30, 2005; 6 pages, 3 figures, uses PoS.cls; to appear in Proceedings of Science
10/2005;
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ABSTRACT: We investigate the vacuum dynamics of U(1), SU(2), and SU(3) lattice gauge theories in presence of external (chromo)magnetic fields, both in (3+1) and (2+1) dimensions. We find that the critical coupling for the phase transition in compact U(1) gauge theory is independent of the strength of an external magnetic field. On the other hand we find that, both in (3+1) and (2+1) dimensions, the deconfinement temperature for SU(2) and SU(3) gauge systems in a constant abelian chromomagnetic field decreases when the strength of the applied field increases. We conclude that the dependence of the deconfinement temperature on the strength of an external constant chromomagnetic field is a peculiar feature of non abelian gauge theories and could be useful to get insight into color confinement. Comment: 26 pages, 14 figures
05/2005;
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ABSTRACT: We investigate the deconfining phase transition in SU(3) pure gauge theory and in full QCD with two flavors of staggered fermions. The phase transition is detected by measuring the free energy in presence of an abelian monopole background field. In the pure gauge case our finite size scaling analysis is in agreement with the well known presence of a weak first order phase transition. In the case of 2 flavors full QCD we find, using the standard pure gauge and staggered fermion actions, that the phase transition is consistent with weak first order, contrary to the expectation of a crossover for not too large quark masses and in agreement with results obtained by the Pisa group. Comment: 23 pages, 11 figures, 4 tables (minor typos corrected, references updated, accepted for publication on JHEP)
01/2004;
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ABSTRACT: Using the lattice Schr\"odinger functional we study vacuum dynamics of SU(3) gauge theory at finite temperature. The 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 implies that strong enough Abelian chromomagnetic fields destroy confinement of color. Comment: Lattice2002(topology). 3 pages, 3 figures
09/2002;
Institutions
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2008–2010
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Università degli Studi di Bari Aldo Moro
Bari,
Apulia,
Italy
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1994–1995
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INFN - Istituto Nazionale di Fisica Nucleare
Legnaro,
Veneto,
Italy
