Fri·Sep 14, 2001Friday·September 14, 2001

1. 01*

   Adaptive Optimization of Wave Functions for Lattice Field Models

   Matteo Beccaria🇮🇹 · Massimo Campostrini🇮🇹 · Alessandra Feo🇩🇪

   The accuracy of Green Function Monte Carlo (GFMC) simulations can be greatly improved by a clever choice of the approximate ground state wave function that controls configuration sampling. This trial wave function typically depends on many free parameters whose fixing is a non trivial task. Here, we discuss a general purpose adaptive algorithm for their non-linear optimization. As a non trivial application we test the method on the two dimensional Wess-Zumino model, a relativistically invariant supersymmetric field theory with interacting bosonic and fermionic degrees of freedom.

   hep-lat8 citations
2. 02*

   The Isgur-Wise function on the lattice

   UKQCD collaboration: G.N. Lacagnina🇬🇧

   The h+, h_A1 form factors for the semi-leptonic B->D and B->D* decays are evaluated in quenched lattice QCD with beta=6.2. The action and the operators are fully O(a) non-perturbatively improved. The Isgur-Wise function is evaluated and fitted to extract its slope; the latter is found to be rho^2=1.1(2)(3) from the B->D* decay and rho^2=1.0(2)(3) from the B->D decay. The form factors ratios R_1, R_2 are evaluated and found to be in agreement with experimental determinations.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·5 citations
3. 03*

   Chiral measurements with the Fixed-Point Dirac operator and construction of chiral currents

   P. Hasenfratz🇨🇭 · S. Hauswirth🇨🇭 · K. Holland🇨🇭 · T. Jorg🇨🇭 · F. Niedermayer🇨🇭

   In this preliminary study, we examine the chiral properties of the parametrized Fixed-Point Dirac operator D^FP, see how to improve its chirality via the Overlap construction, measure the renormalized quark condensate Sigma and the topological susceptibility chi_t, and investigate local chirality of near zero modes of the Dirac operator. We also give a general construction of chiral currents and densities for chiral lattice actions.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·25 citations
4. 04*

   Hydrodynamic scaling from the dynamics of relativistic quantum field theory

   Luis M. A. Bettencourt🇺🇸 · Fred Cooper🇺🇸 · Karen Pao🇺🇸

   Hydrodynamic behavior is a general feature of interacting systems with many degrees of freedom constrained by conservation laws. To date hydrodynamic scaling in relativistic quantum systems has been observed in many high energy settings, from cosmic ray detections to accelerators, with large particle multiplicity final states. Here we show first evidence for the emergence of hydrodynamic scaling in the dynamics of a relativistic quantum field theory. We consider a simple scalar $\lambda {\varphi }^4$ model in 1+1 dimensions in the Hartree approximation and study the dynamics of two colliding kinks at relativistic speeds as well as the decay of a localized high energy density region. The evolution of the energy-momentum tensor determines the dynamical local equation of state and allows the measurement of the speed of sound. Hydrodynamic scaling emerges at high local energy densities.

   ↳ hep-phhep-latnlin.PSnucl-thPRL(2002)·17 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.