Tue·Sep 2, 2003Tuesday·September 2, 2003

1. 01*

   Charmonia above the Deconfinement Phase Transition

   M. Asakawa🇯🇵 · T. Hatsuda🇯🇵

   Analyzing correlation functions of charmonia at finite temperature ($T$) on $32^3\times (32-96)$ anisotropic lattices by the maximum entropy method (MEM), we find that $J/\psi$ and ${\eta }_c$ survive as distinct resonances in the plasma even up to $T\simeq 1.6T_c$ and that they eventually dissociate between $1.6T_c$ and $1.9T_c$ ($T_c$ is the critical temperature of deconfinement). This suggests that the deconfined plasma is non-perturbative enough to hold heavy-quark bound states. The importance of having sufficient number of temporal data points in the MEM analysis is also emphasized.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·10 citations
2. 02*

   Indications for Criticality at Zero Curvature in a 4d Regge Model of Euclidean Quantum Gravity

   Wolfgang Beirl🇺🇸 · Bernd A. Berg🇺🇸

   We re-examine the approach to four-dimensional Euclidean quantum gravity based on the Regge calculus. A cut-off on the link lengths is introduced and consequently the gravitational coupling and the cosmological constant become independent parameters. We determine the zero curvature, $<R>=0$, line in the coupling constant plane by numerical simulations. When crossing this line we find a strong, probably first order, phase transition line with indications of a second order endpoint. Beyond the endpoint the transition through the $<R>=0$ line appears to be a crossover. Previous investigations, using the Regge or the Dynamical Triangulation approach, dealt with a limit in which the first order transition prevails.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·0 citations
3. 03*

   Glueball masses in 4d U(1) lattice gauge theory using the multi-level algorithm

   Pushan Majumdar🇩🇪 · Yoshiaki Koma🇩🇪 · Miho Koma🇩🇪

   We take a new look at plaquette-plaquette correlators in 4d compact U(1) lattice gauge theory which are separated in time, both in the confined and the deconfined phases. From the behaviour of these correlators we extract glueball masses in the scalar as well as the axial-vector channels. Also in the deconfined phase, the non-zero momentum axial-vector correlator gives us information about the photon which appears as a massless particle in the spectrum. Using the Luescher - Weisz multi-level algorithm, we are able to go to large time separations which were not possible previously.

   hep-lathep-thNPB(2004)·22 citations
4. 04*

   Magnetic charge superselection in the deconfined phase of Yang-Mills theory

   M. D'Elia🇮🇹 · A. Di Giacomo🇮🇹 · B. Lucini🇬🇧

   The vacuum expectation value of an operator carrying magnetic charge is studied numerically for temperatures above the deconfinement temperature in SU(2) and SU(3) gauge theory. By analyzing its finite size behaviour, this is found to be exactly zero in the thermodynamical limit for any T > T_c whenever the magnetic charge of the operator is different from zero. These results show that magnetic charge is superselected in the hot phase of quenched QCD.

   hep-latPRD(2004)·11 citations
5. 05*

   External field dependence of the correlation lengths in the three-dimensional O(4) model

   J. Engels🇩🇪 · L. Fromme🇩🇪 · M. Seniuch🇩🇪

   We investigate numerically the transverse and longitudinal correlation lengths of the three-dimensional O(4) model as a function of the external field H. In the low-temperature phase we verify explicitly the H^{-1/2}-dependence of the transverse correlation length, which is expected due to the Goldstone modes of the model. On the critical line we find the universal amplitude ratio xi^c_T / xi^c_L = 1.99(1). From our data we derive the universal scaling function for the transverse correlation length. The H-dependencies of the correlation lengths in the high temperature phase are discussed and shown to be in accord with the scaling functions.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·1 citation
6. 06*

   Instantons and constituent monopoles

   Falk Bruckmann🇳🇱 · Daniel Nogradi🇳🇱 · Pierre van Baal🇳🇱

   We review how instanton solutions at finite temperature can be seen as boundstates of constituent monopoles, discuss some speculations concerning their physical relevance and the lattice evidence for their presence in a dynamical context.

   ↳ hep-thhep-lathep-phActa Phys.Polon.B(2003)·28 citations
7. 07*

   TBA equations for excited states in the O(3) and O(4) nonlinear $\sigma$-model

   J. Balog🇭🇺 · A. Hegedus🇭🇺

   TBA integral equations are proposed for 1-particle states in the sausage- and SS-models and their $\sigma$-model limits. Combined with the ground state TBA equations the exact mass gap is computed in the O(3) and O(4) nonlinear $\sigma$-model and the results are compared to 3-loop perturbation theory and Monte Carlo data.

   ↳ hep-thhep-latJ.Phys.A(2004)·52 citations
8. 08*

   QCD Quark Condensate from SUSY and the Orientifold Large-N Expansion

   A. Armoni🇨🇭 · M. Shifman🇺🇸 · G. Veneziano🇨🇭

   We estimate the quark condensate in one-flavor massless QCD from the known value of the gluino condensate in SUSY Yang-Mills theory using our newly proposed "orientifold" large-N expansion. The numerical result for the quark condensate renormalized at the scale 2 GeV is then given as a function of alpha_s(2 GeV) and of possible corrections from sub-leading terms. Our value can be compared with the quark condensate in (quenched) lattice QCD or with the one extracted from the Gell-Mann--Oakes--Renner relation by virtue of non-lattice determinations of the quark masses. In both cases we find quite a remarkable agreement.

   ↳ hep-thhep-lathep-phPLB(2004)·78 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.