Mon·Sep 9, 2002Monday·September 9, 2002

1. 01*

   High temperature QCD with three flavors of improved staggered quarks

   The MILC Collaboration: C. Bernard (Washington U)🇺🇸 · T. Burch (U Arizona)🇺🇸 · C.E. DeTar (U Utah)🇺🇸 · Steven Gottlieb (Indiana U)🇺🇸 · Eric Gregory (U Arizona)🇺🇸 · U.M. Heller (CSIT FSU)🇺🇸 · J. Osborn (U Utah)🇺🇸 · R.L. Sugar (UCSB)🇺🇸 · D. Toussaint (U Arizona)🇺🇸

   We present an update of our study of high temperature QCD with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad staggered quark action. Simulations are being carried out on lattices with Nt=4, 6 and 8 for the case of three degenerate quarks with masses less than or equal to the strange quark mass, $m_s$, and on lattices with Nt=6 and 8 for degenerate up and down quarks with masses in the range 0.2 m_s \leq m_{u,d} \leq 0.6 m_s, and the strange quark fixed near its physical value. We also report on first computations of quark number susceptibilities with the Asqtad action. These susceptibilities are of interest because they can be related to event-by-event fluctuations in heavy ion collision experiments. Use of the improved quark action leads to a substantial reduction in lattice artifacts. This can be seen already for free fermions and carries over into our results for QCD.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·36 citations
2. 02*

   Color confinement and dual superconductivity in unquenched QCD

   J.M. Carmona🇪🇸 · M. D'Elia🇮🇹 · L. Del Debbio🇮🇹 · A. Di Giacomo🇮🇹 · B. Lucini🇬🇧 · G. Paffuti🇮🇹 · C. Pica🇮🇹

   We report on evidence from lattice simulations that confinement is produced by dual superconductivity of the vacuum in full QCD as in quenched QCD. Preliminary information is obtained on the order of the deconfining phase transition.

   hep-latNPA(2003)·5 citations
3. 03*

   Calorons and BPS monopoles with non-trivial holonomy in the confinement phase of SU(2) gluodynamics

   E.-M. Ilgenfritz🇯🇵 · B.V. Martemyanov🇷🇺 · M. Muller-Preussker🇩🇪 · S. Shcheredin🇩🇪 · A.I. Veselov🇷🇺

   With the help of the cooling method applied to SU(2) lattice gauge theory at non-zero $T\le T_c$ we present numerical evidence for the existence of superpositions of Kraan-van Baal caloron (or BPS monopole pair) solutions with non-trivial holonomy, which might constitute an important contribution to the semi-classical approximation of the partition function.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·15 citations
4. 04*

   Deconfining transition in Full QCD

   J.M. Carmona🇪🇸 · M. D'Elia🇮🇹 · L. Del Debbio🇮🇹 · A. Di Giacomo🇮🇹 · B. Lucini🇬🇧 · G. Paffuti🇮🇹 · C. Pica🇮🇹

   We present evidence that in full QCD with two dynamical quarks confinement is produced by dual superconductivity of the vacuum as in the quenched theory. Preliminary information is obtained on the nature of the deconfining transition.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·10 citations
5. 05*

   Remark on the Theoretical Uncertainty in $B^0$-${\bar{B}}^0$ Mixing

   Sinead M. Ryan🇮🇪 · Andreas S. Kronfeld🇺🇸

   We re-examine the theoretical uncertainty in the Standard Model expression for $B^0$-${\bar{B}}^0$ mixing. We focus on lattice calculations of the ratio $\xi$, needed to relate the oscillation frequency of $B_s^0$-${\bar{B}}_s^0$ mixing to $V_{td}$. We replace the usual linear chiral extrapolation with one that includes the logarithm that appears in chiral perturbation theory. We find a significant shift in the ratio $\xi$, from the conventional $1.15\pm 0.05$ to $\xi =1.32\pm 0.10$.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·3 citations
6. 06*

   QCD phase diagram for small densities from simulations at imaginary mu

   P. de Forcrand (ETH/CERN)🇨🇭 · O. Philipsen (MIT)🇺🇸

   We present results on the QCD phase diagram for small densities without reweighting. Our simulations are performed with an imaginary chemical potential mu_I for which the fermion determinant is positive. On an 8^3x4 lattice with 2 flavors of staggered quarks, we map out the pseudo-critical temperature T_c(mu_I). For mu_I/T < pi/3, this is an analytic function whose Taylor expansion converges rapidly, with truncation errors smaller than statistical ones. The result is analytically continued to give the location of the pseudo-critical line for real mu_B<500 MeV.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·28 citations
7. 07*

   A study of large field configurations in MC simulations

   L. Li🇺🇸 · Y. Meurice🇺🇸

   We discuss a new approach of scalar field theory where the small field contributions are treated perturbatively and the large field configurations (which are responsible for the asymptotic behavior of the perturbative series) are neglected. In two Borel summable lambda phi ^4 problems improved perturbative series can be obtained by this procedure. The modified series converge towards values exponentially close to the exact ones. For lambda larger than some critical value, the method outperforms Pade approximants and Borel summations. The method can also be used for series which are not Borel summable such as the double-well potential series and provide a perturbative approach of the instanton contribution. Semi-classical methods can be used to calculate the modified Feynman rules, estimate the error and optimize the field cutoff. We discuss Monte Carlo simulations in one and two dimensions which support the hypothesis of dilution of large field configurations used in these semi-classical calculations. We show that Monte Carlo methods can be used to calculate the modified perturbative series.

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

   Panel discussion on chiral extrapolation of physical observables

   Claude Bernard🇺🇸 · Shoji Hashimoto🇯🇵 · Derek B. Leinweber🇦🇺 · Peter Lepage🇺🇸 · Elisabetta Pallante🇮🇹 · Stephen R. Sharpe (chair)🇺🇸 · Hartmut Wittig🇩🇪

   This is an approximate reconstruction of the panel discussion on chiral extrapolation of physical observables. The session consisted of brief presentations from panelists, followed by responses from the panel, and concluded with questions and comments from the floor with answers from panelists. In the following, the panelists have summarized their statements, and the ensuing discussion has been approximately reconstructed from notes.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·79 citations
9. 09*

   Topological flux sectors in extended U(1) gauge theory on T^4

   Philippe de Forcrand🇨🇭 · Michele Vettorazzo🇨🇭

   We consider the 4d compact U(1) gauge theory with fundamental-adjoint action on a hypertorus. We give a full characterization of the phase diagram of this model in terms of topological flux sectors.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·2 citations
10. 10*

    k-String Tensions and Center Vortices at Large N

    J. Greensite🇺🇸 · S. Olejnik🇸🇰

    We point out that there is a natural explanation, in terms of the center vortex confinement mechanism, for the expected Casimir/Sine Law scaling of k-string tensions in the large N limit. The crucial ingredient is the existence of Z(N) center monopoles, which go over to U(1) monopoles in this limit. Vortex densities leading to Casimir/Sine Law scaling at large-N are constructed; these densities have no obvious pathologies and in particular do not grow with N. We also note that center vortices are stable classical solutions of the Wilson action, for all SU(N) gauge theories with N>4, and extend this old result to a broad class of lattice actions motivated by the improved action program and the renormalization group.

    hep-lathep-thJHEP(2002)·26 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.