arXiv subjects
Publications and source records attributed to Paolo Cea.
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.
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.
We investigate the quantum Hall effect in graphene. We argue that in graphene in presence of an external magnetic field there is dynamical generation of mass by a rearrangement of the Dirac sea. We show that the mechanism breaks the lattice valley degeneracy only for the $n=0$ Landau levels and leads to the new observed $ν= \pm 1$ quantum Hall plateaus. We suggest that our result can be tested by means of numerical simulations of planar Quantum Electro Dynamics with dynamical fermions in an external magnetic fields on the lattice.
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 $Γ(H) \simeq 340 {\text{GeV}}$.
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.
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.
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.
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.
We discuss the large scale polarization of the cosmic microwave background induced by the anisotropy of the spatial geometry of our universe. Assuming an eccentricity at decoupling of about $0.64 10^{-2}$, we find an average large scale polarization $ΔT_{pol}/ T_0 = (0.5 - 1.0) 10^{-6}$. We suggest that the fortcoming polarization data at large scales from Planck will be able to discriminate between our proposal and the generally accepted reionization scenario.
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.
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.
The method of analytic continuation from imaginary to real chemical potentials $μ$ 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 $μ$: 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 $μ^2 = 0$, but a very large precision would be needed at imaginary $μ$ to correctly predict the location of the critical line at real $μ$.
We calculate the large scale polarization of the cosmic microwave background induced by the anisotropy of the spatial geometry of our universe. Assuming an eccentricity at decoupling of about $0.64 10^{-2}$, we find $ΔT_{pol}/ T_0 \simeq 0.53 10^{-6}$ quite close to the average level of polarization detected by the Wilkinson Microwave Anisotropy Probe.
P-stars are compact stars made of up and down quarks in $β$-equilibrium with electrons in a chromomagnetic condensate. P-stars are able to account for compact stars as well as stars with radius comparable with canonical neutron stars. We compare p-stars with different available observations. Our results indicate that p-stars are able to reproduce in a natural manner several observations from isolated and binary pulsars.
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.
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.
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.
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.