Thu·Oct 6, 2005Thursday·October 6, 2005

1. 01*

   More evidence of localization in the low-lying Dirac spectrum

   C. Bernard🇺🇸 · Ph. de Forcrand🇨🇭 · Steven Gottlieb🇺🇸 · U.M. Heller🇺🇸 · J.E. Hetrick🇺🇸 · O. Jahn🇺🇸 · L. Levkova🇺🇸 · F. Maresca🇺🇸 · D.B. Renner🇺🇸 · R. Sugar🇺🇸 · D. Toussaint🇺🇸

   We have extended our computation of the inverse participation ratio of low-lying (asqtad) Dirac eigenvectors in quenched SU(3). The scaling dimension of the confining manifold is clearer and very near 3. We have also computed the 2-point correlator which further characterizes the localization.

   hep-latPoS(2006)·22 citations
2. 02*

   Remarks on the Maximum Entropy Method applied to finite temperature lattice QCD

   Takashi Umeda🇺🇸 · Hideo Matsufuru🇯🇵

   We make remarks on the Maximum Entropy Method (MEM) for studies of the spectral function of hadronic correlators in finite temperature lattice QCD. We discuss the virtues and subtlety of MEM in the cases that one does not have enough number of data points such as at finite temperature. Taking these points into account, we suggest several tests which one should examine to keep the reliability for the results, and also apply them using mock and lattice QCD data.

   hep-latPoS(2006)·4 citations
3. 03*

   Cho-Faddeev-Niemi decomposition of lattice Yang-Mills theory and evidence of a novel magnetic condensation

   Akihiro Shibata🇯🇵 · Kei-Ichi Kondo🇯🇵 · Seikou Kato🇯🇵 · Takeharu Murakami🇯🇵 · Toru Shinohara🇯🇵

   We present the first implementation of the Cho--Faddeev--Niemi ecomposition of the SU(2) Yang-Mills field on a lattice. Our construction retains the color symmetry (global SU(2) gauge invariance) even after a new type of Maximally Abelian gauge, as explicitly demonstrated by numerical simulations.

   hep-latPoS(2006)·1 citation
4. 04*

   Towards an algebraic approach to the discretisation of fermions

   Vivien de Beauce🇯🇵

   A discretisation scheme for differential geometry is applied to the problem of constructing lattice actions, the naive and staggered action are thus derived. It is found that after specifying an ansatz for the space of fields, the corresponding lattice action is obtained. The gauging procedure, and the applicability of the method to twisted super-symmetry on a lattice is outlined. Some comments on the QED axial anomaly are made, for the theory in which the lattice projection operator is not inserted.

   hep-latPoS(2006)·4 citations
5. 05*

   Optimization of Lattice QCD codes for the AMD Opteron processor

   Miho Koma (DESY / RCNP Osaka Univ.)🇩🇪

   We report our experience of the optimization of the lattice QCD codes for the new Opteron cluster at DESY Hamburg, including benchmarks. Details of the optimization using SSE/SSE2 instructions and the effective use of prefetch instructions are discussed.

   hep-latNucl.Instrum.Meth.A(2006)·0 citations
6. 06*

   Supersymmetric Yang-Mills quantum mechanics in various dimensions

   Jacek Wosiek🇵🇱 · Massimo Campostrini🇮🇹

   Supersymmetric Yang-Mills quantum mechanics (SYMQM) results from the dimensional reduction of the Yang-Mills field theory in $D$ space-time dimensions to a single point in the $D-1$ dimensional space. It can be also viewed as the effective quantum mechanics of zero momentum modes of the original theory. These systems were first considered in 80's as simple models with supersymmetry. Independently, zero-volume field theories (especially pure Yang-Mills) were employed as the starting point of the small volume expansion, which is an important theoretical tool complementary to early lattice calculations. Later the models attracted a new wave of interest after the hypothesis of the equivalence, between the $D=10,SU(\infty )$ SYMQM and a M-theory of D0 branes. In this talk some new results obtained for the D=4 system with SU(2) gauge symmetry will be presented.

   hep-latPoS(2006)·1 citation
7. 07*

   Meson correlation functions at high temperatures

   S. Wissel🇩🇪 · S. Datta🇺🇸 · F. Karsch🇺🇸 · E. Laermann🇩🇪 · S. Shcheredin🇩🇪

   We present preliminary results for the correlation- and spectral functions of different meson channels on the lattice. The main focus lies on gaining control over cut-off as well as on the finite-volume effects. Extrapolations of screening masses above the deconfining temperature are guided by the result of the free ($T=\infty$) case on the lattice and in the continuum. We study the quenched non-perturbatively improved Wilson-clover fermion as well as the hypercube fermion action which might show less cut-off effects.

   hep-latPoS(2006)·27 citations
8. 08*

   Bound state spectrum in the finite volume

   Shoichi Sasaki (RIKEN BNL)🇺🇸 · Takeshi Yamazaki (RIKEN BNL)🇺🇸

   The signature of bound state formation on the lattice is of particular interest in this talk. In the finite volume, where all states have discrete energies, it is rather hard to distinguish between a bound state and a scattering state if the bound state were close to threshold, i.e., like a "loosely bound state". To study bound states in the finite volume, we calculate the positronium spectroscopy in the Higgs phase of U(1) gauge dynamics, where the photon is massive and then massive photons give rise to the short-ranged interparticle force. We try to identify bound state formation on the basis of the Luscher's finite size method, which suggests specific volume dependences of the energy gap/shift from the threshold energy for either bound states or scattering states.

   hep-latPoS(2006)·4 citations
9. 09*

   On the determination of low-energy constants for $\Delta S=1$ transitions

   L. Giusti🇨🇭 · P. Hernandez🇪🇸 · M. Laine🇩🇪 · C. Pena🇨🇭 · J. Wennekers🇩🇪 · H. Wittig🇩🇪

   We present our preliminary results for three-point correlation functions involving the operators entering the $\Delta S=1$ effective Hamiltonian with an active charm quark, obtained using overlap fermions in the quenched approximation. This is the first computation carried out for valence quark masses small enough so as to permit a matching to Quenched Chiral Perturbation Theory in the $ϵ$-regime. The commonly observed large statistical fluctuations are tamed by means of low-mode averaging techniques, combined with restrictions to individual topological sectors. We also discuss the matching of the resulting hadronic matrix elements to the effective low-energy constants for $\Delta S=1$ transitions. This involves (a) finite-volume corrections which can be evaluated at NLO in Quenched Chiral Perturbation Theory, and (b) the short-distance renormalization of the relevant four-quark operators in discretizations based on the overlap operator. We discuss perturbative estimates for the renormalization factors and possible strategies for their non-perturbative evaluation. Our results can be used to isolate the long-distance contributions to the $\Delta I=1/2$ rule, coming from physics effects around the intrinsic QCD scale.

   hep-latPoS(2006)·8 citations
10. 10*

    Non-Perturbative Quark-Antiquark Production From a Constant Chromo-Electric Field via the Schwinger Mechanism

    Gouranga C. Nayak (SUNY, Stony Brook)🇺🇸

    We obtain an exact result for the non-perturbative quark (antiquark) production rate and its p_T distribution from a constant SU(3) chromo-electric field E^a with arbitary color index $a$ by directly evaluating the path integral. Unlike the WKB tunneling result, which depends only on one gauge invariant quantity |E|, the strength of the chromo-electric field, we find that the exact result for the p_T distribution for quark (antiquark) production rate depends on two independent Casimir (gauge) invariants, E^aE^a and [d_{abc}E^aE^bE^c]^2.

    ↳ hep-phhep-lathep-thnucl-thPRD(2005)·108 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.