2,894 research outputs found
Continuum limit and universality of the Columbia plot
No full textResults on the thermal transition of QCD with 3 degenerate flavors, in the lower-left corner of the Columbia plot, are puzzling. The transition is expected to be first-order for massless quarks, and to remain so for a range of quark masses until it turns second-order at a critical quark mass. But this critical quark mass and resulting "pion" mass disagree violently between Wilson and staggered fermions at finite lattice spacing, and decrease sharply with the lattice spacing, for staggered fermions at least. To clarify this puzzle and eliminate potential systematic effects from rooting, we study the 4-flavor theory with staggered fermions, on lattices with 4 to 10 time-slices. Our results are qualitatively similar to the 3-flavor case, so that rooting is not an issue. However, dramatic cutoff effects are visible, even on our finest lattices. Universality implies that cutoff effects for Wilson fermions are even more dramatic. In order to obtain a first-order thermal transition in the continuum theory, extremely light quarks are needed
More on electric and magnetic fluxes in SU(2)
No full textAlso published in: arXiv:hep-lat/0212019v1, 12 Dec 2002: 1-3The free energies of static charges and center monopoles are given by their fluxes. While electric fluxes show the universal behaviour of the deconfinement transition, the monopole free energies vanish in the thermodynamic limit at all temperatures and are thus irrelevant for the transition. Magnetic fluxes may, however, be used to measure the topological susceptibility without cooling.Lorenz von Smekal with Philippe de Forcrand and Oliver Jah
The interaction between center monopoles in SU(2) Yang-Mills
No full textWe study the potential between a static center monopole and antimonopole in
4d SU(2) Yang-Mills theory. Using a new numerical method, we show that the 't
Hooft loop is a dual order parameter with respect to the Wilson loop, for the
deconfinement phase transition. We observe a 3d Ising-like critical behaviour
for the dual string tension related to the spatial 't Hooft loop as a function
of the temperature
A study of the 't Hooft loop in SU(2) Yang-Mills theory
No full textWe study the behaviour of the spatial and temporal 't Hooft loop at zero and
finite temperature in the 4D SU(2) Yang-Mills theory, using a new numerical
method. In the deconfined phase , the spatial 't Hooft loop exhibits a
dual string tension, which vanishes at with 3D Ising-like critical
exponent
Deconfinement phase transition in one-flavor QCD
No full textWe present a study of the deconfinement phase transition of one-flavor QCD using the multiboson algorithm. The mass of the Wilson fermions relevant for this study is moderately large and the non-Hermitian multiboson method is a superior simulation algorithm. Finite-size scaling is studied on lattices of size (Formula presented) (Formula presented), and (Formula presented). The behaviors of the peak of the Polyakov loop susceptibility, the deconfinement ratio, and the distribution of the norm of the Polyakov loop are all characteristic of a first-order phase transition for heavy quarks. As the quark mass decreases, the first-order transition gets weaker and turns into a crossover. To investigate finite-size scaling on larger spatial lattices we use an effective action in the same universality class as QCD. This effective action is constructed by replacing the fermionic determinant with the Polyakov loop identified as the most relevant (Formula presented)-symmetry-breaking term. Higher-order effects are incorporated in an effective (Formula presented)-breaking field h, which couples to the Polyakov loop. Finite-size scaling determines the value of h where the first-order transition ends. Our analysis at the end point (Formula presented) indicates that the effective model and thus QCD are consistent with the universality class of the three-dimensional Ising model. Matching the field strength at the end point (Formula presented) to the (Formula presented) values used in the dynamical quark simulations we estimate the end point (Formula presented) of the first-order phase transition. We find (Formula presented) which corresponds to a quark mass of about 1.4 GeV. © 1999 The American Physical Society
Histoire de la Deuxième Guerre Mondiale (1992-1997) (09). Philippe Burrin (1) - face A
No full textSéminaire organisé et enregistré par l'IHTP (Paris), entre 1992 et 1997 ; sous la direction de Jean-Pierre Azéma et Dominique Veillon. Communication de Philippe Burrin
Histoire de la Deuxième Guerre Mondiale (1992-1997) (09). Philippe Burrin (1) - face B
No full textSéminaire organisé et enregistré par l'IHTP (Paris), entre 1992 et 1997 ; sous la direction de Jean-Pierre Azéma et Dominique Veillon. Communication de Philippe Burrin
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