Tue·Oct 21, 2003Tuesday·October 21, 2003

1. 01*

   Phase Fluctuation of Fermion Determinant in Lattice QCD at Finite Density

   Y. Sasai (Oshima National Coll.)🇯🇵 · A. Nakamura (Hiroshima U.)🇯🇵 · T. Takaishi (Hiroshima U. of Economics)🇯🇵

   Once the quark chemical potential $\mu$ is introduced in finite density QCD, the fermion determinant appeared in the path integral measure becomes complex. In order to investigate the phase effect of SU(3) lattice QCD (2-flavors), we calculated the fluctuation of the phase of $\det \Delta (\mu )$ on a $8^3\times 4$ lattice at $\mu =0.1$ and 0.2. Then we calculated the chiral condensate and Polyakov line in the no phase and reweighted cases. There is little difference between these two cases at $\mu =0.1$ and 0.2. We consider a possible reason for this result below $\mu \le 0.27$ in terms of $Z_3$ symmetry.

   hep-latNucl.Phys.B Proc.Suppl.(2004)·21 citations
2. 02*

   Recent progress in calculating weak matrix elements using staggered fermions

   Weonjong Lee🇰🇷

   We present a chronological review of the progress in calculating weak matrix elements using staggered fermions. We review the perturbative calculation of one-loop matching formula including both current-current diagrams and penguin diagrams using improved staggered fermions. We also present preliminary results of weak matrix elements relevant to CP violation calculated using the improved (HYP (II)) staggered fermions. Since the complete set of matching coefficients at the one-loop level became available recently, we have constructed lattice operators with all the $g^2$ corrections included. The main results include both $\Delta I=3/2$ and $\Delta I=1/2$ contributions.

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

   Solution of the Dirac equation in lattice QCD using a domain decomposition method

   Martin Lüscher🇨🇭

   Efficient algorithms for the solution of partial differential equations on parallel computers are often based on domain decomposition methods. Schwarz preconditioners combined with standard Krylov space solvers are widely used in this context, and such a combination is shown here to perform very well in the case of the Wilson--Dirac equation in lattice QCD. In particular, with respect to even-odd preconditioned solvers, the communication overhead is significantly reduced, which allows the computational work to be distributed over a large number of processors with only small parallelization losses.

   hep-latComput.Phys.Commun.(2004)·184 citations
4. 04*

   Beauty Hadron Lifetimes and B-Meson CP-Violation Parameters from Lattice QCD

   Cecilia Tarantino🇮🇹

   The present status of the theoretical estimates of beauty hadron lifetime ratios and of width differences and CP-violation parameters in $B_d$ and $B_s$ systems is reviewed. In the last two years accurate lattice calculations and next-to-leading order perturbative computations have improved these theoretical predictions, leading to the following updated results: \tau(B^+)/\tau(B_d)=1.06 +- 0.02, \tau(B_s)/\tau(B_d)=1.00 +- 0.01, \tau(\Lambda_b)/\tau(B_d)=0.88 +- 0.05, \Delta \Gamma_{d}/\Gamma_{d} = (2.42 +- 0.59)10^{-3}, \Delta \Gamma_{s}/\Gamma_{s} = (7.4 +- 2.4)10^{-2}, |(q/p)_d|-1=(2.96 +- 0.67) 10^{-4}$ and |(q/p)_s|-1=-(1.28 +- 0.28) 10^{-5}

   ↳ hep-phhep-latEPJC(2004)·74 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.