Thu·Oct 27, 2005Thursday·October 27, 2005

1. 01*

   Light-Quark FLIC Fermion Simulations of the $1^{-+}$ Exotic Meson

   J.N. Hedditch🇦🇺 · W. Kamleh🇦🇺 · B.G. Lasscock🇦🇺 · D.B. Leinweber🇦🇺 · A.G. Williams🇦🇺 · J.M. Zanotti🇩🇪

   We investigate the mass of the $1^{-+}$ exotic meson, created with hybrid interpolating fields. Access to light quark masses approaching 25 MeV is facilitated by the use of the Fat-Link Irrelevant Clover (FLIC) fermion action, and large ($20^3\times 40$) lattices. Our results indicate that the $1^{-+}$ exotic exhibits significant curvature close to the chiral limit, and yield a $1^{-+}$ mass in agreement with the ${\pi }_1(1600)$ candidate and exclusive of the ${\pi }_1(1400)$.

   hep-latPoS(2006)·0 citations
2. 02*

   Quantization of empty space

   M.A. Zubkov🇷🇺

   We suggest to use "minimal" choice of quantum gravity theory, that is the quantum field theory, in which space-time is seen as Riemannian space and metric (or vierbein field) is the dynamical variable. We then suggest to use the simplest acceptable action, that is the squared curvature action. The correspondent model is renormalizable, has the correct classical limit without matter and can be explored using Euclidian path integral formalism. In order to get nonperturbative results one has to put this model on the lattice. While doing so serious problems with measure over dynamical variables are encountered, which were not solved until present. We suggest to solve them using the representation of Riemannian space as a limiting case of Riemann - Cartan space, where the Poincare group connection plays the role of dynamical variable. We construct manifestly gauge invariant discretization of Riemann - Cartan space. Lattice realization of Poincare gauge transformation naturally acts on the dynamical variables of the constructed discretization. There exists local measure invariant under this gauge transformation, which could be used as a basic element of lattice path integral methods. The correspondent lattice model appears to be useful for numerical simulations.

   hep-lat0 citations
3. 03*

   Supercurrent Flow in NJL_{2+1} at High Baryon Density

   Simon Hands🇬🇧 · Avtar Singh Sehra🇬🇧

   We present results of numerical simulations of the 2+1d Nambu -- Jona-Lasinio model with non-zero baryon chemical potential mu and spatially-varying complex diquark source strength j. By choosing arg(j) to vary smoothly through 2 pi across the spatial extent of the lattice, a baryon number current is induced which in the high density phase remains non-vanishing as |j|->0; we are hence able to extract a quantity characteristic of a superfluid known as the helicity modulus. We also study supercurrent flow at non-zero temperature and estimate the critical temperature at which the normal phase is restored, which is consistent with the conventional picture for thin-film superfluids in which the transition is viewed in terms of vortex -- anti-vortex unbinding.

   hep-latcond-mat.supr-connucl-thPLB(2006)·3 citations
4. 04*

   Simulations in Early Universe Theory

   Jan Smit🇳🇱

   We give an impression of the type of results that have been obtained with numerical lattice simulations of field theory in the early universe.

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

   On the effective string spectrum of the tridimensional Z(2) gauge model

   Michele Caselle🇮🇹 · Martin Hasenbusch🇮🇹 · Marco Panero🇮🇪

   We study the Z(2) lattice gauge theory in three dimensions, and present high precision estimates for the first few energy levels of the string spectrum. These results are obtained from new numerical data for the two-point Polyakov loop correlation function, which is measured in the 3d Ising spin system using duality. This allows us to perform a stringent comparison with the predictions of effective string models. We find a remarkable agreement between the numerical estimates and the Nambu-Goto predictions for the energy gaps at intermediate and large distances. The precision of our data allows to distinguish clearly between the predictions of the full Nambu-Goto action and the simple free string model up to an interquark distance $r\approx 10/\sqrt{\sigma }$. At the same time, our results also confirm the breakdown of the effective picture at short distances, supporting the hypothesis that terms which are not taken into account in the usual Nambu-Goto string formulation yield a non-trivial shift to the energy levels. Furthermore, we discuss the theoretical implications of these results.

   hep-lathep-phhep-thJHEP(2006)·25 citations
6. 06*

   Biased Metropolis-Heat-Bath Algorithm for Fundamental-Adjoint SU(2) Lattice Gauge Theory

   Alexei Bazavov🇺🇸 · Bernd A. Berg🇺🇸 · Urs M. Heller🇺🇸

   For SU(2) lattice gauge theory with the fundamental-adjoint action an efficient heat-bath algorithm is not known so that one had to rely on Metropolis simulations supplemented by overrelaxation. Implementing a novel biased Metropolis-heat-bath algorithm for this model, we find improvement factors in the range 1.45 to 2.06 over conventionally optimized Metropolis simulations. If one optimizes further with respect to additional overrelaxation sweeps, the improvement factors are found in the range 1.3 to 1.8.

   hep-latPRD(2005)·13 citations
7. 07*

   Spectral properties of the Landau gauge Faddeev-Popov operator in lattice gluodynamics

   A. Sternbeck🇩🇪 · E.-M. Ilgenfritz🇩🇪 · M. Mueller-Preussker🇩🇪

   Recently we reported on the infrared behavior of the Landau gauge gluon and ghost dressing functions in SU(3) Wilson lattice gluodynamics with special emphasis on the Gribov problem. Here we add an investigation of the spectral properties of the Faddeev-Popov operator at $\beta$=5.8 and 6.2 for lattice sizes 12^4, 16^4 and 24^4. The larger the volume the more of its eigenvalues are found accumulated close to zero. Using the eigenmodes for the spectral representation it turns out that for our smallest lattice O(200) eigenmodes are sufficient to saturate the ghost propagator at lowest momentum. We associate exceptionally large values of the ghost propagator to extraordinary contributions of low-lying eigenmodes.

   hep-latPRD(2006)·52 citations
8. 08*

   Equation of state for agents on graphs

   A. Majka🇵🇱 · W. Wislicki🇵🇱

   Choice models for populations of agents on graphs are studied in terms of statistical thermodynamics. Equations of state are derived and discussed for different connectivity schemes, utility approximations, and temperature and volume regimes. Analogies to ideal classical and quantum gases are found and features specific for network systems are discussed.

   ↳ cond-mat.stat-mechhep-latEur.Phys.J.B(2005)·0 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.