Tue·Oct 1, 2002Tuesday·October 1, 2002

1. 01*

   Excitations of the nucleon with dynamical fermions

   UKQCD collaboration · C.M. Maynard · LHP collaboration · D.G. Richards

   We measure the spectrum of low-lying nucleon resonances using Bayesian fitting methods. We compare the masses obtained in the quenched approximation to those obtained with two flavours of dynamical fermions at a matched lattice spacing. At the pion masses employed in our simulations, we find that the mass of the first positive-parity nucleon excitation is always greater than that of the parity partner of the nucleon.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·18 citations
2. 02*

   Critical behavior in a quasi D dimensional spin model

   Erhard Seiler🇩🇪 · Karim Yildirim🇩🇪

   We study a classical spin model (more precisely a class of models) with O(N) symmetry that can be viewed as a simplified $D$ dimensional lattice model. It is equivalent to a non-translationinvariant one dimensional model and contains the dimensionality $D$ as a parameter that need not be an integer. The critical dimension turns out to be 2, just as in the usual translation invariant models. We study the phase structure, critical phenomena and spontaneous symmetry breaking. Furthermore we compute the perturbation expansion to low order with various boundary conditions. In our simplified models a number of questions can be answered that remain controversial in the translation invariant models, such as the asymptoticity of the perturbation expansion and the role of super-instantons. We find that perturbation theory produces the right asymptotic expansion in dimension $D\le 2$ only with special boundary conditions. Finally the model allows a test of the percolation ideas of Patrascioiu and Seiler.

   hep-latcond-mat.stat-mechmath-phmath.MPJ.Statist.Phys.(2003)·2 citations
3. 03*

   The CKM Lattice Working Group initiative

   Jonathan Flynn (1)🇬🇧 · Laurent Lellouch (2)🇫🇷 · Guido Martinelli (3) ((1) Southampton U., (2) CPT Marseille, (3) Univ. di Roma I)🇮🇹

   We present the CKM-LWG, a collection of working groups whose aim is to compile world averages of lattice results relevant for high-energy phenomenology.

   hep-lathep-phNucl.Phys.B Proc.Suppl.(2003)·2 citations
4. 04*

   Non-perturbative renormalization constants and light quark masses

   D.Becirevic🇮🇹 · V.Gimenez🇮🇹 · V.Lubicz🇮🇹 · G.Martinelli🇮🇹 · M.Papinutto🇮🇹 · J.Reyes🇮🇹 · C.Tarantino [SPQcdR Collaboration]🇮🇹

   We present the results of an extensive non-perturbative calculation of the renormalization constants of bilinear quark operators for the non-perturbatively O(a)-improved Wilson action. The results are obtained at four values of the lattice coupling, by using the RI/MOM and the Ward identities methods. A new non-perturbative renormalization technique, which is based on the study of the lattice correlation functions at short distance in x-space, is also numerically investigated. We then use our non-perturbative determination of the quark mass renormalization constants to compute the values of the strange and the average up/down quark masses. After performing an extrapolation to the continuum limit, we obtain ms^msbar(2 GeV) = (106 +- 2 +- 8) MeV and ml^msbar(2 GeV)=(4.4 +- 0.1 +- 0.4) MeV.

   hep-latNucl.Phys.B Proc.Suppl.(2003)·8 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.