Tue·Sep 14, 2004Tuesday·September 14, 2004

1. 01*

   Chiral extrapolations with small sea quark mass data in two-flavor lattice QCD

   CP-PACS Collaboration: Y.Namekawa🇯🇵 · S.Aoki🇯🇵 · M.Fukugita🇯🇵 · K-I.Ishikawa🇯🇵 · N.Ishizuka🇯🇵 · Y.Iwasaki🇯🇵 · K.Kanaya🇯🇵 · T.Kaneko🇯🇵 · Y.Kuramashi🇯🇵 · V.I.Lesk🇯🇵 · M.Okawa🇯🇵 · A.Ukawa🇯🇵 · T.Umeda🇯🇵 · T.Yoshié🇯🇵

   We present results on the light hadron spectrum and quark mass in two-flavor QCD calculated with small sea quark masses down to $m_{PS}/m_V=0.35$. The configurations are generated using the RG improved gauge and tadpole-improved clover quark action at $\beta =1.8$, where $a^{-1}\simeq 1$ GeV. Chiral extrapolations are made using not only polynomials and ChPT in the continuum but also formulae of Wilson chiral perturbation theory (WChPT) including $O(a^2)$ chiral breaking terms. We examine the viability of WChPT and its influence on quark masses.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·0 citations
2. 02*

   A finite temperature investigation of the Georgi-Glashow model in 3D

   A. Barresi🇮🇹 · L. Del Debbio🇨🇭 · B. Lucini🇨🇭

   We study the SU(2) gauge theory with scalar matter in the adjoint representation in 3D at finite temperature. We find evidence for a finite temperature phase transition both in the symmetric and in the broken phase; such transitions are consistent with the universality class of Ising 2D, in agreement with recent analytical arguments.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
3. 03*

   Density profiles of small Dirac operator eigenvalues for two color QCD at nonzero chemical potential compared to matrix models

   Gernot Akemann🇬🇧 · Elmar Bittner🇩🇪 · Maria-Paola Lombardo🇮🇹 · Harald Markum🇦🇹 · Rainer Pullirsch🇦🇹

   We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian Symplectic Ensemble, confirming its predictions for weak and strong non-Hermiticity. They differ from the QCD symmetry class with three colors by a level repulsion from both the real and imaginary axis.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·11 citations
4. 04*

   Calculating ${ϵ}^{\prime }/ϵ$ using HYP staggered fermions

   Tanmoy Bhattacharya🇺🇸 · George T. Fleming🇺🇸 · Rajan Gupta🇺🇸 · Greg Kilcup🇺🇸 · Weonjong Lee🇰🇷 · Stephen Sharpe🇺🇸

   We present preliminary results for ${ϵ}^{\prime }/ϵ$ calculated using HYP staggered fermions in the quenched approximation. We compare different choices of quenched penguin operators.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·19 citations
5. 05*

   Testing improved staggered fermions with $m_s$ and $B_K$

   Weonjong Lee🇰🇷 · Tanmoy Bhattacharya🇺🇸 · George T. Fleming🇺🇸 · Rajan Gupta🇺🇸 · Gregory Kilcup🇺🇸 · Stephen R. Sharpe🇺🇸

   We study the improvement of staggered fermions using hypercubically smeared (HYP) links. We calculate the strange quark mass and the kaon B-parameter, $B_K$, in quenched QCD on a $16^3\times 64$ lattice at $\beta =6.0$. We find $m_s(\overline{\mathrm{MS}},2\mathrm{GeV})=101.2\pm 1.3\pm 4$MeV and $B_K(\overline{\mathrm{MS}},2\mathrm{GeV})=0.578\pm 0.018\pm 0.042$, where the first error is from statistics and fitting, and the second from using one-loop matching factors. The scale ($1/a=1.95$GeV) is set by $M_{\rho }$, and $m_s$ is determined using the kaon mass. Comparing to quenched results obtained using unimproved staggered fermions and other discretizations, we argue that the size of discretization errors in $B_K$ is substantially reduced by improvement.

   hep-latPRD(2005)·21 citations
6. 06*

   Semileptonic Hyperon Decays on the Lattice: an Exploratory Study

   D. Guadagnoli🇮🇹 · G. Martinelli🇮🇹 · M. Papinutto🇩🇪 · S. Simula🇮🇹

   We present preliminary results of an exploratory lattice study of the vector form factor $f_1(q^2=0)$ relevant for the semileptonic hyperon decay ${\Sigma }^{-}-->nl\nu$. This study is based on the same method used for the extraction of $f^{+}(0)$ for the decay $K^0-->{\pi }^{-}l\nu$. The main purpose of this study is to test the method for hyperon form factors in order to estimate the precision that can be reached and the importance of SU(3)-breaking effects.

   hep-lathep-phNucl.Phys.B Proc.Suppl.(2005)·13 citations
7. 07*

   B_K from improved staggered quarks

   E. Gamiz🇬🇧 · S. Collins🇬🇧 · C. T. H. Davies🇬🇧 · J. Shigemitsu🇺🇸 · M. Wingate (HPQCD and UKQCD collaborations)🇺🇸

   We compare calculations of B_K with improved staggered quarks (HYP, Asqtad) and demonstrate the improved scaling behaviour that this gives rise to over previous calculations with unimproved staggered quarks. This enables us to perform the calculation of B_K on the MILC dynamical configurations (n_f=2+1), for which we give preliminary results.

   hep-lathep-phNucl.Phys.B Proc.Suppl.(2005)·12 citations
8. 08*

   Deconfinement and Chiral Restoration in Hot and Dense Matter

   Kenji Fukushima🇺🇸

   We propose a picture that the chiral phase transition at zero quark mass and the deconfinement transition at infinite quark mass are continuously connected. This gives a simple interpretation on the coincidence of the pseudo-critical temperatures observed in lattice QCD. We discuss a possible dynamical mechanism behind the simultaneous crossovers and show the results in a model study.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
9. 09*

   Topological susceptibility with three flavors of staggered quarks

   C. Aubin (1)🇺🇸 · C. Bernard (1)🇺🇸 · Brian Billeter (2)🇺🇸 · C. DeTar (2)🇺🇸 · Steven Gottlieb (3)🇺🇸 · E. Gregory (4)🇺🇸 · U.M. Heller (5)🇺🇸 · J.E. Hetrick (6)🇺🇸 · J. Osborn (2)🇺🇸 · R.L. Sugar (7)🇺🇸 · D. Toussaint (4) ((1) Wash. U., (2) U. Utah, (3) Indiana U., (4) U. Arizona, (5) APS, (6) U. Pacific, (7) UCSB)🇺🇸

   As one test of the validity of the staggered-fermion fourth-root determinant trick, we examine the suppression of the topological susceptibility of the QCD vacuum in the limit of small quark mass. The suppression is sensitive to the number of light sea quark flavors. Our study is done in the presence of 2+1 flavors of dynamical quarks in the improved staggered fermion formulation. Variance-reduction techniques provide better control of statistical errors. New results from staggered chiral perturbation theory account for taste-breaking effects in the low-quark mass behavior of the susceptibility, thereby reducing scaling violations from this source. Measurements over a range of quark masses at two lattice spacings permit a rough continuum extrapolation to remove the remaining lattice artifacts. The results are consistent with chiral perturbation theory with the correct flavor counting.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·6 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.