PaperPanorama

HEP Lattice·hep-lat

Tue·Oct 16, 2007

14 papers—13 primary·1 cross-listed·reconstructed*

All14Primary13Cross-lists1
  1. 01*

    Topological defects and equation of state of gluon plasma

    M.N. Chernodub🇷🇺 · Katsuya Ishiguro🇯🇵 · Atsushi Nakamura🇯🇵 · Toru Sekido🇯🇵 · Tsuneo Suzuki🇯🇵 · V.I. Zakharov🇮🇹

    We show that the degrees of freedom associated with magnetic monopole- and vortexlike gluonic configurations make a strong contribution to the anomaly of the energy-momentum tensor of Yang-Mills theory in the deconfinement phase immediately above the critical temperature. As is well known in zero-temperature Yang-Mills theory, the monopoles and vortices are constituents of a generic gluonic object in which the two neighbor monopoles are connected together by a segment of vortex string. Our results provide evidence that the monopole-vortex chains in SU(2) gauge theory and their SU(3) counterparts, the monopole-vortex nets, are thermodynamically relevant degrees of freedom in the gluonic plasma.

    hep-lathep-phhep-thPoS(2007)·15 citations
  2. 02*

    The chiral transition on a 24^3x10 lattice with N_f=2 clover sea quarks studied by overlap valence quarks

    V. Weinberg🇩🇪 · E.-M. Ilgenfritz🇩🇪 · K. Koller🇩🇪 · Y. Koma🇩🇪 · Y. Nakamura🇩🇪 · G. Schierholz🇩🇪 · T. Streuer🇺🇸

    Overlap fermions are particularly well suited to study the finite temperature dynamics of the chiral symmetry restoration transition of QCD, which might be just an analytic crossover. Using gauge field configurations on a 24^3x10 lattice with N_f=2 flavours of dynamical Wilson-clover quarks generated by the DIK collaboration, we compute the lowest 50 eigenmodes of the overlap Dirac operator and try to locate the transition by fermionic means. We analyse the spectral density, local chirality and localisation properties of the low-lying modes and illustrate the changing topological and (anti-) selfdual structure of the underlying gauge fields across the transition.

    hep-latPoS(2007)·4 citations
  3. 03*

    Localization of overlap modes and topological charge, vortices and monopoles in SU(3) LGT

    E.-M. Ilgenfritz🇩🇪 · K. Koller🇩🇪 · Y. Koma🇩🇪 · G. Schierholz🇩🇪 · T. Streuer🇺🇸 · V. Weinberg🇩🇪 · M. Quandt🇩🇪

    We present selected recent results of the QCDSF collaboration on the localization and dimensionality of low overlap eigenmodes and of the topological density in the quenched SU(3) vacuum. We discuss the correlations between the topological structure revealed by overlap fermions without filtering and the confining monopole and P-vortex structure obtained in the Indirect Maximal Center Gauge.

    hep-latPoS(2007)·20 citations
  4. 04*

    The Polyakov Loop and the Eigenvalues of the Dirac Operator

    Wolfgang Söldner🇺🇸

    Aiming at the link between confinement and chiral symmetry the Polyakov loop represented as a spectral sum of eigenvalues of the Dirac operator was subject of recent studies. We analyze the volume dependence as well as the continuum behavior of this quantity for quenched QCD using staggered fermions. Furthermore, we present first results using dynamical configurations.

    hep-latPoS(2007)·7 citations
  5. 05*

    Lattice simulation of 2+1 flavors of overlap light quarks

    JLQCD collaboration: S. Hashimoto🇯🇵 · S. Aoki🇯🇵 · H. Fukaya🇯🇵 · T. Kaneko🇯🇵 · H. Matsufuru🇯🇵 · J. Noaki🇯🇵 · T. Onogi🇯🇵 · N. Yamada🇯🇵

    We report on the status of the dynamical overlap QCD simulation project by the JLQCD collaboration. After completing two-flavor QCD simulation on a 16^3x32 lattice at lattice spacing a 0.12 fm, we started a series of runs with 2+1 flavors. In this report, we describe an outline of our algorithms, parameter choices, and some early physics results of this second phase of our project.

    hep-latPoS(2007)·18 citations
  6. 06*

    Electromagnetic form factors of the Delta baryon

    Constantia Alexandrou🇨🇾 · Tomasz Korzec🇨🇾 · Theodoros Leontiou🇨🇾 · John W. Negele🇺🇸 · Antonios Tsapalis🇬🇷

    We develop a methodology that enables us to extract accurately the electromagnetic Delta form factors and their momentum dependence. We test our approach in the quenched approximation as a preparation for a study using dynamical fermions. Our calculation of the four form factors covers pion masses between about 410 MeV and 560 MeV on lattices with a size of 2.9 fm and a lattice spacing 0.09 fm. From the form factors we are able to obtain estimates of the magnetic moment and the charge radius of the Delta, which we compare to existing experimental and theoretical results.Our non-zero result for the electric quadrupole form factor signals a deformation of the Delta, pointing to an oblate charge distribution.

    hep-lathep-phnucl-thPoS(2007)·29 citations
  7. 07*

    Exploring the QCD vacuum - (some) recent developments in confinement and topology

    Falk Bruckmann🇩🇪

    I start by giving a brief overview over new developments in the area of confinement and topology. As an example for the interrelations between topological objects, instantons at finite temperature are discussed. Then I focus on new insights into the structure of the QCD vacuum obtained through filtering methods, in particular those based on decompositions w.r.t. fermionic eigenmodes.

    hep-lathep-phhep-thPoS(2007)·9 citations
  10. 10*

    Study of the topological vacuum structure of SU(2) gluodynamics at T > 0 with overlap fermions and improved action

    V.G.Bornyakov🇷🇺 · E.V.Luschevskaya🇷🇺 · S.M.Morozov🇷🇺 · M.I.Polikarpov🇷🇺 · E.M.Ilgenfritz🇩🇪 · M.Muller-Preussker🇩🇪

    We study SU(2) gluodynamics at finite temperature near the deconfining phase transition. We create the lattice ensembles using the tadpole improved Luscher-Weisz action. The overlap Dirac operator is used to determine the following three aspects of vacuum structure: (i) The topological susceptibility is evaluated at various temperatures across the phase transition, (ii) the overlap fermion spectral density is determined and found to depend on the Polyakov loop above the phase transition and (iii) the corresponding localization properties of low lying eigenmodes are investigated.

    hep-latPoS(2007)·6 citations
  11. 11*

    Non-perturbative renormalisation of four-fermion operators in N_f=2 QCD

    P. Dimopoulos🇮🇹 · G. Herdoiza🇮🇹 · F. Palombi🇨🇭 · M. Papinutto🇨🇭 · C. Pena🇪🇸 · A. Vladikas🇮🇹 · H. Wittig🇩🇪

    We present results for the non-perturbative renormalisation of four-fermion operators with two flavours of dynamical quarks. We consider both fully relativistic left current-left current operators, and a full basis for operators with static heavy quarks. The renormalisation group running of the operators to high energy scales is computed in the continuum limit for a family of Schroedinger Functional renormalisation schemes, via standard finite size scaling techniques. The total renormalisation factors relating renormalisation group invariant to bare operators are computed for a choice of lattice regularisations.

    hep-latPoS(2007)·5 citations
  12. 12*

    First quenched results for the matrix elements of the B_{B_s} mixing parameter in the static limit from tmQCD

    F.Palombi🇨🇭 · M.Papinutto🇨🇭 · C.Pena🇪🇸 · H.Wittig🇩🇪

    We report on a non-perturbative study of the scale-dependent renormalization factors of a multiplicatively renormalizable basis of Delta B=2 parity-odd four-fermion operators in quenched lattice QCD. We also present some preliminary results of the matrix elements related to the mixing parameter of the B_s-meson. In our lattice formulation, the heavy quark is treated in the static approximation, while the strange one belongs to a doublet of twisted mass fermions at full twist, i.e. with twist angle alpha=pi/2. In this framework, the parity-even Delta B=2 four-fermion operators responsible for the mixing are rotated onto a linear combination of parity-odd operators in the above-mentioned basis. Their physical matrix elements between static B_s-mesons are extracted from lattice correlators with Schroedinger functional boundary conditions. We observe a suppression of excited state contributions to the B_{B_s} mixing parameter and speculate about possible explanations.

    hep-latPoS(2007)·1 citation
  13. 13*

    A determination of the B_s^0 and B_d^0 mixing parameters in 2+1 lattice QCD

    R. Todd Evans🇺🇸 · Elvira Gamiz🇺🇸 · Aida X. El-Khadra🇺🇸 · Massimo Di Pierro🇺🇸

    We report on the advances in our unquenched calculation of the matrix elements relevant for the analysis of B^0-\bar B^0 mixing using the Asqtad (light quark) and Fermilab (heavy quark) actions. We have calculated the hadronic parameters for the mass and width differences in the neutral B meson system. Preliminary results are presented for f_{B_q}^2 B_q as well as for the ratio \xi^2=f_{B_s}^2 B_{B_s}/f_{B_d}^2 B_{B_d}.

    hep-latPoS(2007)·13 citations
  14. 14*

    PNJL model with a Van der Monde term

    Sanjay K. Ghosh🇮🇳 · Tamal K. Mukherjee🇮🇳 · Munshi G. Mustafa🇮🇳 · Rajarshi Ray🇮🇳

    We extend the Polyakov-Nambu-Jona-Lasinio (PNJL) model for two degenerate flavours by including the effect of the SU(3) measure with a Van der Monde (VdM) term. This ensures that the Polyakov loop always remains in the domain [0,1]. The pressure, energy density, specific heat, speed of sound and conformal measure show small or negligible effects from this term. However various quark number and isospin susceptibilities are all found to approach their respective ideal gas limits around 2 . We compare our methods with other similar approaches in PNJL model and also present a quantitative comparison with Lattice QCD data.

    ↳ hep-phhep-latnucl-thPRD(2008)·115 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.