Mon·Oct 31, 2005Monday·October 31, 2005

1. 01*

   Topology conserving gauge action and the overlap-Dirac operator

   H.Fukaya🇯🇵 · S.Hashimoto🇯🇵 · T.Hirohashi🇯🇵 · K.Ogawa🇯🇵 · T.Onogi🇯🇵

   We apply the topology conserving gauge action proposed by Luescher to the four-dimensional lattice QCD simulation in the quenched approximation. With this gauge action the topological charge is stabilized along the hybrid Monte Carlo updates compared to the standard Wilson gauge action. The quark potential and renormalized coupling constant are in good agreement with the results obtained with the Wilson gauge action. We also investigate the low-lying eigenvalue distribution of the hermitian Wilson-Dirac operator, which is relevant for the construction of the overlap-Dirac operator.

   hep-latPRD(2006)·34 citations
2. 02*

   Topology with Dynamical Overlap Fermions

   G. I. Egri🇭🇺 · Z. Fodor🇩🇪 · S. D. Katz🇭🇺 · K.K. Szabo🇩🇪

   We perform dynamical QCD simulations with $n_f=2$ overlap fermions by hybrid Monte-Carlo method on $6^4$ to $8^3\times 16$ lattices. We study the problem of topological sector changing. A new method is proposed which works without topological sector changes. We use this new method to determine the topological susceptibility at various quark masses.

   hep-latJHEP(2006)·47 citations
3. 03*

   The Sign Problem is the Solution

   J.C. Osborn🇺🇸 · K. Splittorff🇩🇰 · J.J.M. Verbaarschot🇺🇸

   The unquenched spectral density of the Dirac operator at $\mu \ne 0$ is complex and has oscillations with a period inversely proportional to the volume and an amplitude that grows exponentially with the volume. Here we show how the oscillations lead to the discontinuity of the chiral condensate.

   hep-lat6 citations
4. 04*

   Chiral properties of dynamical Wilson fermions

   Roland Hoffmann🇩🇪

   We consider two-flavor QCD in the lattice regularization with improved Wilson fermions. In this formulation chiral symmetry is explicitly broken at order a and hence the isovector axial currents require improvement as well as a finite renormalization if they are to satisfy continuum Ward--Takahashi identities up to small lattice corrections of O(a^2). Algorithmic difficulties at coarse lattice spacings, where HMC suffers from a distorted Dirac spectrum, are discussed. This is shown to be a cutoff effect, which disappears rapidly as the lattice spacing is decreased. An alternative algorithm, the polynomial hybrid Monte Carlo algorithm, is found to perform significantly better in the presence of exceptionally small eigenvalues. Extending previously used methods both the improvement and the renormalization of the axial current are implemented non--perturbatively in terms of correlation functions formulated in the framework of the Schroedinger functional. In both cases this is achieved by enforcing continuum Ward identities at finite lattice spacing. Together, this restores the isovector chiral symmetry to quadratic order in the lattice spacing. With little additional effort the normalization factor of the local vector current is also obtained.

   hep-lat4 citations
5. 05*

   Exact-propagator instantaneous Bethe-Salpeter equation for quark-antiquark bound states

   Z.-F. Li · Wolfgang Lucha🇦🇹 · F. F. Schoberl🇦🇹

   Recently, an instantaneous approximation to the Bethe-Salpeter formalism for the analysis of bound states in quantum field theory has been proposed which retains, in contrast to the Salpeter equation, as far as possible the exact propagators of the bound-state constituents, extracted nonperturbatively from Dyson-Schwinger equations or lattice gauge theory. The implications of this improvement for the solutions of this bound-state equation, that is, the spectrum of the mass eigenvalues of its bound states and the corresponding wave functions, when considering the quark propagators arising in quantum chromodynamics are explored.

   ↳ hep-phhep-latnucl-thMod.Phys.Lett.A(2006)·13 citations
6. 06*

   A study of the gauge invariant, nonlocal mass operator $Tr\int d^{4}x{F}_{\mu \nu }(D^2{)}^{-1}{F}_{\mu \nu }$ in Yang-Mills theories

   M.A.L. Capri🇧🇷 · D. Dudal🇧🇪 · J.A. Gracey🇬🇧 · V.E.R. Lemes🇧🇷 · R.F. Sobreiro🇧🇷 · S.P. Sorella🇧🇷 · H. Verschelde🇧🇪

   The nonlocal mass operator $Tr\int d^{4}x{F}_{\mu \nu }(D^2{)}^{-1}{F}_{\mu \nu }$ is considered in Yang-Mills theories in Euclidean space-time. It is shown that the operator $Tr\int d^{4}x{F}_{\mu \nu }(D^2{)}^{-1}{F}_{\mu \nu }$ can be cast in local form through the introduction of a set of additional fields. A local and polynomial action is thus identified. Its multiplicative renormalizability is proven by means of the algebraic renormalization in the class of linear covariant gauges. The anomalous dimensions of the fields and of the mass operator are computed at one loop order. A few remarks on the possible role of this operator for the issue of the gauge invariance of the dimension two condensates are outlined.

   ↳ hep-thhep-lathep-phPRD(2005)·61 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.