Thu·Sep 25, 2003Thursday·September 25, 2003

1. 01*

   I=2 pion-pion scattering phase shift in the continuum limit calculated with two-flavor full QCD

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

   We present a calculation of the scattering phase shift for the I=2 S-wave pion-pion system in the continuum limit with two-flavor full QCD. Calculations are made at three lattice spacings, using the finite volume method of Lüscher in the center of mass frame, and its extension to the laboratory frame.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·13 citations
2. 02*

   Maximum Entropy Method Approach to $\theta$ Term

   Masahiro Imachi🇯🇵 · Yasuhiko Shinno🇯🇵 · Hiroshi Yoneyama🇯🇵

   In Monte Carlo simulations of lattice field theory with a $\theta$ term, one confronts the complex weight problem, or the sign problem. This is circumvented by performing the Fourier transform of the topological charge distribution $P(Q)$. This procedure, however, causes flattening phenomenon of the free energy $f(\theta )$, which makes study of the phase structure unfeasible. In order to treat this problem, we apply the maximum entropy method (MEM) to a Gaussian form of $P(Q)$, which serves as a good example to test whether the MEM can be applied effectively to the $\theta$ term. We study the case with flattening as well as that without flattening. In the latter case, the results of the MEM agree with those obtained from the direct application of the Fourier transform. For the former, the MEM gives a smoother $f(\theta )$ than that of the Fourier transform. Among various default models investigated, the images which yield the least error do not show flattening, although some others cannot be excluded given the uncertainty related to statistical error.

   hep-latProg.Theor.Phys.(2004)·10 citations
3. 03*

   Chirally improving Wilson fermions

   R. Frezzotti🇮🇹 · G.C. Rossi🇮🇹

   It is possible to improve the chiral behaviour and the approach to the continuum limit of correlation functions in lattice QCD with standard and twisted Wilson fermions by taking arithmetic averages of correlators computed in theories regularized with Wilson terms of opposite sign. To avoid the problem of the spurious zero-modes of the Wilson--Dirac operator, twisted-mass lattice QCD should be used for the actual computation of the correlators taking part in the averages. A particularly useful choice for the twisting angle is $\pm \pi /2$ where many physical quantities (e.g. masses and zero-momentum matrix elements) are automatically improved with no need of averaging.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·17 citations
4. 04*

   Higher orders of the high-temperature expansion for the Ising model in three dimensions

   H. Arisue🇯🇵 · T. Fujiwara🇯🇵 · K. Tabata🇯🇵

   The new algorithm of the finite lattice method is applied to generate the high-temperature expansion series of the simple cubic Ising model to ${\beta }^{50}$ for the free energy, to ${\beta }^{32}$ for the magnetic susceptibility and to ${\beta }^{29}$ for the second moment correlation length. The series are analyzed to give the precise value of the critical point and the critical exponents of the model.

   hep-latcond-mat.stat-mechNucl.Phys.B Proc.Suppl.(2004)·7 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.