1,720,997 research outputs found
Nf = 1 QCD in external magnetic fields: staggered fermions
No full textAbstract: We investigate Nf = 1 QCD in external magnetic fields on the lattice. The background field is introduced by means of the so-called Schrödinger functional. We adopt standard staggered fermions with constant bare mass am = 0.025 and magnetic fields with constant magnetic flux up to a2eH ≃ 2.3562. We find that the the deconfinement and chiral symmetry restoration temperatures do not depend on the strength of the applied magnetic field. Our method allow us to easily study the effects of the external magnetic fields on the QCD thermodynamics. We determine the influences of applied magnetic fields to the free energy, pressure, and equation of state of strongly interacting matter
Critical line of 2+1 flavor QCD: Toward the continuum limit
Full text linkWe determine the continuum limit of the curvature of the pseudocritical line of QCD with nf=2+1 staggered fermions at nonzero temperature and quark density. We perform Monte Carlo simulations at imaginary baryon chemical potentials with Highly Improved Staggered Quarks (HISQ), adopting the HISQ/tree action discretization as implemented in the code by the MILC Collaboration. Couplings are adjusted so as to move on a line of constant physics, as determined in Ref. [1], with the strange quark mass ms fixed at its physical value and a light-to-strange mass ratio ml/ms=1/20. The chemical potential is set at the same value for the three quark species, μl=μs≡μ. We attempt an extrapolation to the continuum using the results on lattices with temporal size up to Lt=12. Our estimate for the continuum value of the curvature κ at zero baryon density, κ=0.020(4), is compared with recent lattice results and with experimental determinations of the freeze-out curve
PROBING CONFINEMENT WITH CHROMOMAGNETIC FIELDS
No full textUsing the lattice Schrödinger 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
Curvature of the pseudocritical line in (2+1)-flavor QCD with HISQ fermions
No full textWe study QCD with (2+1)-HISQ fermions at nonzero temperature and nonzero imaginary baryon chemical potential. Monte Carlo simulations are performed using the MILC code along the line of constant physics with a light to strange mass ratio of ml/ms =1/20 on lattices up to 483 X 12 to check for finite cutoff effects. We determine the curvature of the pseudocritical line extrapolated to the continuum limit
INDICATIONS ON THE HIGGS BOSON MASS FROM LATTICE SIMULATIONS
No full textThe 'triviality' of Φ44 has been traditionally interpreted within perturbation theory where the prediction for the Higgs boson mass depends on the magnitude of the ultraviolet cutoff A. This approach crucially assumes that the vacuum field and its quantum fluctuations rescale in the same way. The results of the present lattice simulation, confirming previous numerical indications, show that this assumption is not true. As a consequence, large values of the Higgs mass mH can coexist with the limit Λ → ∞. As an example, by extrapolating to the Standard Model our results obtained in the Ising limit of the one-component theory, one can obtain a value as large as mH = 760 ± 21 GeV, independently of Λ. © 2004 Published by Elsevier B.V
Anatomy of SU(3) flux tubes at finite temperature
No full textAn attempt to adapt the study of color flux tubes to the case of finite temperature has been made. The field is measured both through the correlator of two Polyakov loops, one of which connected to a plaquette, and through a connected correlator of Wilson loop and plaquette in the spatial sublattice. Still the profile of the flux tube resembles the transverse field distribution around an isolated vortex in an ordinary superconductor. The temperature dependence of all the parameters characterizing the flux tube is investigated
Flux tubes in the QCD vacuum
Full text linkThe hypothesis that the QCD vacuum can be modeled as a dual superconductor is a powerful tool to describe the distribution of the color field generated by a quark-antiquark static pair and, as such, can provide useful clues for the understanding of confinement. In this work we investigate, by lattice Monte Carlo simulations of the SU(3) pure gauge theory and of (2+1)-flavor QCD with physical mass settings, some properties of the chromoelectric flux tube at zero temperature and their dependence on the physical distance between the static sources. We draw some conclusions about the validity domain of the dual superconductor picture
Flux tubes at finite temperature
Full text linkAbstract: The chromoelectric field generated by a static quark-antiquark pair, with its peculiar tube-like shape, can be nicely described, at zero temperature, within the dual superconductor scenario for the QCD confining vacuum. In this work we investigate, by lattice Monte Carlo simulations of the SU (3) pure gauge theory, the fate of chromoelectric flux tubes across the deconfinement transition. We find that, if the distance between the static sources is kept fixed at about 0.76fm≃1.6/σ and the temperature is increased towards and above the deconfinement temperature Tc, the amplitude of the field inside the flux tube gets smaller, while the shape of the flux tube does not vary appreciably across deconfinement. This scenario with flux-tube “evaporation” above Tchas no correspondence in ordinary (type-II) superconductivity, where instead the transition to the phase with normal conductivity is characterized by a divergent fattening of flux tubes as the transition temperature is approached from below. We present also some evidence about the existence of flux-tube structures in the magnetic sector of the theory in the deconfined phase
Monopole Condensation in full QCD using the Schroedinger Functional
No full textWe use a lattice thermal partition functional to study Abelian monopole
condensation in full QCD with staggered fermions. We present
preliminary results on and lattices
QCD flux tubes across the deconfinement phase transition
No full textWe study the behavior across the deconfinement phase transition of the chro-moelectric flux tube generated by a static quark and a static antiquark for several distances between them. We present preliminary results for distances up to 1.33 fm and temperatures up to 1.5Tc
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