Fri·Sep 21, 2001Friday·September 21, 2001

1. 01*

   Lattice results for the decay constant of heavy-light vector mesons

   C. Bernard🇺🇸 · P. Williams🇺🇸 · S. Datta🇺🇸 · Steven Gottlieb🇺🇸 · C. DeTar🇺🇸 · Urs M. Heller🇺🇸 · C. McNeile🇬🇧 · K. Orginos🇺🇸 · R. Sugar🇺🇸 · D. Toussaint🇺🇸

   We compute the leptonic decay constants of heavy-light vector mesons in the quenched approximation. The reliability of lattice computations for heavy quarks is checked by comparing the ratio of vector to pseudoscalar decay constant with the prediction of Heavy Quark Effective Theory in the limit of infinitely heavy quark mass. Good agreement is found. We then calculate the decay constant ratio for B mesons: $f_{B^{\ast }}/f_B=1.01(0.01){(}_{-0.01}^{+0.04})$. We also quote quenched $f_{B^{\ast }}=177(6)(17)$ MeV.

   hep-latPRD(2002)·20 citations
2. 02*

   Perturbation Calculation of the Axial Anomaly of a Ginsparg-Wilson lattice Dirac operator

   Ting-Wai Chiu🇹🇼 · Tung-Han Hsieh🇹🇼

   A recent proposal suggests that even if a Ginsparg-Wilson lattice Dirac operator does not possess any topological zero modes in topologically-nontrivial gauge backgrounds, it can reproduce correct axial anomaly for sufficiently smooth gauge configurations, provided that it is exponentially-local, doublers-free, and has correct continuum behavior. In this paper, we calculate the axial anomaly of this lattice Dirac operator in weak coupling perturbation theory, and show that it recovers the topological charge density in the continuum limit.

   hep-lathep-phhep-thmath-ph+1PRD(2002)·16 citations
3. 03*

   Thermodynamics of 2 and 3 flavour QCD

   Frithjof Karsch🇩🇪

   We discuss recent results on the thermodynamics of QCD in the presence of light dynamical quark degrees of freedom. In particular, we concentrate on an analysis of the flavour and quark mass dependence of the QCD phase diagram, the equation of state and the transition temperature. Moreover, we present recent results on the heavy quark free energy.

   hep-latAIP Conf.Proc.(2001)·15 citations
4. 04*

   Cluster Percolation and Explicit Symmetry Breaking in Spin Models

   Santo Fortunato (U. of Bielefeld)🇩🇪 · Helmut Satz (U. of Bielefeld)🇩🇪

   Many features of spin models can be interpreted in geometrical terms by means of the properties of well defined clusters of spins. In case of spontaneous symmetry breaking, the phase transition of models like the q-state Potts model, O(n), etc., can be equivalently described as a percolation transition of clusters. We study here the behaviour of such clusters when the presence of an external field H breaks explicitly the global symmetry of the Hamiltonian of the theory. We find that these clusters have still some interesting relationships with thermal features of the model.

   hep-latcond-matNucl.Phys.B Proc.Suppl.(2002)·2 citations
5. 05*

   Families index theory for Overlap lattice Dirac operator. I

   David H. Adams🇦🇺

   The index bundle of the Overlap lattice Dirac operator over the orbit space of lattice gauge fields is introduced and studied. Obstructions to the vanishing of gauge anomalies in the Overlap formulation of lattice chiral gauge theory have a natural description in this context. Our main result is a formula for the topological charge (integrated Chern character) of the index bundle over even-dimensional spheres in the orbit space. It reduces under suitable conditions to the topological charge of the usual (continuum) index bundle in the classical continuum limit (this is announced and sketched here; the details will be given in a forthcoming paper). Thus we see that topology of the index bundle of the Dirac operator over the gauge field orbit space can be captured in a finite-dimensional lattice setting.

   hep-lathep-thmath-phmath.MPNPB(2002)·11 citations
6. 06*

   Lattice Chiral Symmetry and the Wess-Zumino Model

   Kazuo Fujikawa🇯🇵 · Masato Ishibashi (Dept. of Physics, Univ. of Tokyo)🇯🇵

   A lattice regularization of the supersymmetric Wess-Zumino model is studied by using Ginsparg-Wilson operators. We recognize a certain conflict between the lattice chiral symmetry and the Majorana condition for Yukawa couplings, or in Weyl representation a conflict between the lattice chiral symmetry and Yukawa couplings. This conflict is also related, though not directly, to the fact that the kinetic (Kähler) term and the superpotential term are clearly distinguished in the continuum Wess-Zumino model, whereas these two terms are mixed in the Ginsparg-Wilson operators. We illustrate a case where lattice chiral symmetry together with naive Bose-Fermi symmetry is imposed by preserving a SUSY-like symmetry in the free part of the Lagrangian; one-loop level non-renormalization of the superpotential is then maintained for finite lattice spacing, though the finite parts of wave function renormalization deviate from the supersymmetric value. All these properties hold for the general Ginsparg-Wilson algebra independently of the detailed construction of lattice Dirac operators.

   ↳ hep-thhep-lathep-phNPB(2002)·40 citations
7. 07*

   Quantum Field Theory on Noncommutative Spaces

   Richard J. Szabo🇬🇧

   A pedagogical and self-contained introduction to noncommutative quantum field theory is presented, with emphasis on those properties that are intimately tied to string theory and gravity. Topics covered include the Weyl-Wigner correspondence, noncommutative Feynman diagrams, UV/IR mixing, noncommutative Yang-Mills theory on infinite space and on the torus, Morita equivalences of noncommutative gauge theories, twisted reduced models, and an in-depth study of the gauge group of noncommutative Yang-Mills theory. Some of the more mathematical ideas and techniques of noncommutative geometry are also briefly explained.

   ↳ hep-thcond-matgr-qchep-lat+4Phys.Rept.(2003)·1804 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.