Fri·Sep 13, 2002Friday·September 13, 2002

1. 01*

   QCD String Spectrum 2002

   K. Jimmy Juge🇨🇭 · Julius Kuti🇺🇸 · Colin Morningstar🇺🇸

   Results from a comprehensive new analysis on the excitation spectrum of the QCD string are presented. A rapid onset of string formation is observed in the spectrum on a length scale of 2 fm, with Dirichlet boundary conditions. The crossover from the short distance spectrum towards string excitations and an observed fine structure in the 1--3 fm range are related to effective string theory. The deficiencies of the Nambu-Goto bosonic string model in describing the observed spectrum are briefly discussed.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·6 citations
2. 02*

   Finite size effects on $M_{\pi }$ in QCD from Chiral Perturbation Theory

   G. Colangelo🇨🇭 · S. Dürr🇩🇪 · R. Sommer🇩🇪

   We present a determination of the shift $M_{\pi }(L)-M_{\pi }$ due to the finite spatial box size $L$ by means of $N_f=2$ Chiral Perturbation Theory and Lüscher's formula. The range of applicability of the chiral prediction is discussed.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·29 citations
3. 03*

   Finite Size Effects in Nucleon Masses in Dynamical QCD

   A. Ali Khan🇩🇪 · T. Bakeyev🇷🇺 · M. Göckeler🇩🇪 · R. Horsley🇬🇧 · A. C. Irving🇬🇧 · D. Pleiter🇩🇪 · P. Rakow🇩🇪 · G. Schierholz🇩🇪 · H. Stüben (QCDSF and UKQCD Collaborations)🇩🇪

   For lattice calculations with light dynamical quarks, finite size effects have become an important aspect. We study finite size effects in nucleon masses on N_f=2 dynamical lattices of 1-2 fm. Predictions for the finite size effects are obtained in one-loop chiral perturbation theory.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·14 citations
4. 04*

   The lattice scale at large beta in quenched QCD

   M. Guagnelli🇮🇹 · R. Petronzio🇮🇹 · N. Tantalo🇮🇹

   In this paper we extend the estimate of the value of the lattice spacing a in units of the r0 scale at values of the bare coupling larger than those available. By using results from the computation of the renormalised coupling in the Schroedinger functional formalism we find that from beta \simeq 7 onward the behaviour predicted by asymptotic freedom at tree loop describes very well the data if a value of (r0 Lambda) slightly lower then the latest available is used. We also show that, by sticking to the current value, an effective four loop term can describe as well the data. The systematic relative error on the lattice spacing induced by the choice of the procedure is between 1% and 3% for 6.92 < beta < 8.5.

   hep-latPLB(2002)·19 citations
5. 05*

   fB from finite size effects in lattice QCD

   M. Guagnelli🇮🇹 · F. Palombi🇮🇹 · R. Petronzio🇮🇹 · N. Tantalo🇮🇹

   We discuss a novel method to calculate fB on the lattice based on the study of the dependence of finite size effects upon the heavy quark mass of flavoured mesons and on a non--perturbative recursive finite size technique. This method avoids the systematic errors related to extrapolations from the static limit or to the tuning of the coefficients of effective Lagrangian and the results admit an extrapolation to the continuum limit. We show the results of a first estimate at finite lattice spacing, but close to the continuum limit, giving fB = 170(11)(5)(22)MeV. We also obtain fBs = 192(9)(5)(24)MeV. The first error is statistical, the second is our estimate of the systematic error from the method and the third the systematic error from the specific approximations adopted in this first exploratory calculation. The method can be generalized to two--scale problems in lattice QCD.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·5 citations
6. 06*

   The QCD equation of state at finite T and \mu

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

   We calculate the pressure (p), the energy density (\epsilon) and the baryon density (n_B) of QCD at finite temperatures (T) and chemical potentials (\mu). The recently proposed overlap improving multi-parameter reweighting technique is used to determine observables at nonvanishing chemical potentials. Our results are obtained by studying n_f=2+1 dynamical staggered quarks with semi-realistic masses on N_t=4 lattices.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·19 citations
7. 07*

   A scalable PC-based parallel computer for lattice QCD

   Z. Fodor🇭🇺 · S.D. Katz🇩🇪 · G. Papp🇭🇺

   A PC-based parallel computer for medium/large scale lattice QCD simulations is suggested. The Eotvos Univ., Inst. Theor. Phys. cluster consists of 137 Intel P4-1.7GHz nodes. Gigabit Ethernet cards are used for nearest neighbor communication in a two-dimensional mesh. The sustained performance for dynamical staggered(wilson) quarks on large lattices is around 70(110) GFlops. The exceptional price/performance ratio is below $1/Mflop.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·1 citation
8. 08*

   Heavy to light vector meson semileptonic decays

   A.Abada🇫🇷 · D.Becirevic🇮🇹 · Ph.Boucaud🇫🇷 · J.M.Flynn🇬🇧 · J.P.Leroy🇫🇷 · V.Lubicz🇮🇹 · F.Mescia🇬🇧

   New (preliminary) results for the form factors relevant for the semileptonic decays of heavy pseudoscalar to a light vector meson are presented. In particular, we discuss the form factors for D --> K* and B --> rho modes.

   hep-lathep-exhep-phNucl.Phys.B Proc.Suppl.(2003)·58 citations
9. 09*

   Chiral Symmetry Restoration and Deconfinement of Light Mesons at Finite Temperature

   Hu Li🇺🇸 · C. M. Shakin🇺🇸

   There has been a great deal of interest in understanding the properties of quantum chromodynamics (QCD) for a finite value of the chemical potential and for finite temperature. Studies have been made of the restoration of chiral symmetry in matter and at finite temperature. The phenomenon of deconfinement is also of great interest, with studies of the temperature dependence of the confining interaction reported recently. In the present work we study the change of the properties of light mesons as the temperature is increased. For this study we make use of a Nambu--Jona-Lasinio (NJL) model that has been generalized to include a covariant model of confinement. The parameters of the confining interaction are made temperature-dependent to take into account what has been learned in lattice simulations of QCD at finite temperature. The constituent quark masses are calculated at finite temperature using the NJL model. A novel feature of our work is the introduction of a temperature dependence of the NJL interaction parameters. (This is a purely phenomenological feature of our model, which we do not attempt to derive from more fundamental considerations.) With the three temperature-dependent aspects of the model mentioned above, we find that the mesons we study are no longer bound when the temperature reaches the critical temperature, $T_c$, which we take to be 170 MeV. We believe that ours is the first model that is able to describe the interplay of chiral symmetry restoration and deconfinement for mesons at finite temperature. The introduction of temperature-dependent coupling constants is a feature of our work whose further consequences should be explored in future work.

   ↳ hep-phhep-lat9 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.