Fri·Sep 12, 2003Friday·September 12, 2003

1. 01*

   $\gamma N\to \Delta$ transition form factors in Quenched and $N_F=2$ QCD

   C. Alexandrou (Univ. of Cyprus)🇨🇾 · Ph. de Forcrand (CERN & ETH Zurich)🇨🇭 · Th. Lippert (Univ. of Wuppertal)🇩🇪 · H. Neff (Univ. of Athens and Boston Univ.)🇺🇸 · J. W. Negele (MIT)🇺🇸 · K. Schilling (Univ. of Wuppertal)🇩🇪 · W. Schroers (MIT)🇺🇸 · A. Tsapalis (Univ. of Cyprus)🇨🇾

   Calculations of the magnetic dipole, electric quadrupole and Coulomb quadrupole amplitudes for the transition $\gamma N\to \Delta$ are presented both in quenched QCD and with two flavours of degenerate dynamical quarks.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·6 citations
2. 02*

   Lattice QCD at finite isospin density and/or temperature

   J.B.Kogut🇺🇸 · D.K.Sinclair🇺🇸

   We simulate two-flavour lattice QCD with at a finite chemical potential ${\mu }_I$ for isospin, and finite temperature. At small ${\mu }_I$, we determine the position of the crossover from hadronic matter to a quark-gluon plasma as a function of ${\mu }_I$. At larger ${\mu }_I$ we observe the phase transition from the superfluid pion-condensed phase to a quark-gluon plasma, noting its change from second order to first order as ${\mu }_I$ is increased. We also simulate two-flavour lattice QCD at zero quark mass, using an action which includes an additional 4-fermion interaction, at temperatures close to the chiral transition on $N_t=8$ lattices.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·9 citations
3. 03*

   Scaling Behavior of the Landau Gauge Overlap Quark Propagator

   J. B. Zhang🇦🇺 · F. D. R. Bonnet🇦🇺 · P. O. Bowman🇦🇺 · D. B. Leinwebwer🇦🇺 · A. G. Williams🇦🇺

   The properties of the momentum space quark propagator in Landau gauge are examined for the overlap quark action in quenched lattice QCD. Numerical calculations are done on three lattices with different lattice spacings and similar physical volumes to explore the approach of the quark propagator towards the continuum limit. We have calculated the nonperturbative momentum-dependent wavefunction renormalization function $Z(p^2)$ and the nonperturbative mass function $M(p^2)$ for a variety of bare quark masses and extrapolate to the chiral limit. We find the behavior of $Z(p^2)$ and $M(p^2)$ are in good agreement for the two finer lattices in the chiral limit. The quark condensate is also calculated.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·5 citations
4. 04*

   Global Monte Carlo for fermions using ordered statistics

   Artan Borici🇬🇧

   In this talk I discuss a new possibility for stochastic representation of the fe rmion determinant. The method can be used for global Monte Carlo fermion algorit hms and is tested in the case of the Schwinger model.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·2 citations
5. 05*

   An Algorithm for Obtaining Reliable Priors for Constrained-Curve Fits

   Terrence Draper🇺🇸 · Shao-Jing Dong🇺🇸 · Ivan Horvath🇺🇸 · Frank Lee🇺🇸 · Nilmani Mathur🇺🇸 · Jianbo Zhang🇦🇺

   We introduce the ``Sequential Empirical Bayes Method'', an adaptive constrained-curve fitting procedure for extracting reliable priors. These are then used in standard augmented-chi-square fits on separate data. This better stabilizes fits to lattice QCD overlap-fermion data at very low quark mass where a priori values are not otherwise known. We illustrate the efficacy of the method with data from overlap fermions, on a quenched $16^3\times 28$ lattice with spatial size La=3.2 fm and pion mass as low as $\sim$ 180 MeV.

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

   Particle distributions in electroweak tachyonic preheating

   Jon-Ivar Skullerud🇳🇱 · Jan Smit🇳🇱 · Anders Tranberg🇳🇱

   We consider the out-of-equilibrium (quasi-) particle number distributions of the Higgs and W-fields during electroweak tachyonic preheating. We model this process by a fast quench, and perform classical real-time lattice simulations in the SU(2)-Higgs model in three dimensions. We discuss how to define particle numbers and effective energies using two-point functions in Coulomb and unitary gauge, and consider some of the associated problems. After an initial exponential growth in effective particle numbers, the system stabilises, allowing us to extract effective masses, temperatures and chemical potentials for the particles.

   hep-lathep-phNucl.Phys.B Proc.Suppl.(2004)·2 citations
7. 07*

   Dyson-Schwinger Equations: An Instrument for Hadron Physics

   A. Krassnigg🇺🇸 · C.D. Roberts🇺🇸

   Dyson-Schwinger equations furnish a Poincare' covariant approach to hadron physics. They reveal that dynamical chiral symmetry breaking is tied to the long-range behaviour of the strong interaction and make predictions corroborated by modern lattice-QCD simulations. A hallmark in the contemporary use of DSEs is the existence of a nonperturbative, symmetry preserving truncation that enables the proof of exact results. The systematic error associated with the truncation's leading term has been quantified and this underpins an efficacious one-parameter model that is being employed to study meson excited states.

   ↳ nucl-thhep-lathep-phnucl-exNPA(2004)·24 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.