Tue·Sep 7, 2004Tuesday·September 7, 2004

1. 01*

   Bulk first-order phase transition in three-flavor lattice QCD with $O(a)$-improved Wilson fermion action at zero temperature

   JLQCD collaboration: S. Aoki🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · K-I. Ishikawa🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 · M. Okawa🇯🇵 · N. Tsutsui🇯🇵 · A. Ukawa🇯🇵 · N. Yamada🇯🇵 · T. Yoshié🇯🇵

   Three-flavor QCD simulation with the $O(a)$-improved Wilson fermion action is made employing an exact fermion algorithm developed for odd number of quark flavors. For the plaquette gauge action, an unexpected first-order phase transition is found in the strong coupling regime ($\beta \lesssim$ 5.0) at relatively heavy quark masses ($m_{\mathrm{PS}}/m_{\mathrm{V}}\sim$ 0.74--0.87). Strong metastability persists on a large lattice of size $12^3\times 32$, which indicates that the transition has a bulk nature. The phase gap becomes smaller toward weaker couplings and vanishes at $\beta \simeq 5.0$, which corresponds to a lattice spacing $a\simeq$ 0.1 fm. The phase transition is not found if the improved gauge actions are employed. Our results imply that realistic simulations of QCD with three flavors of dynamical Wilson-type fermions at lattice spacings in the range $a=$ 0.1--0.2 fm require use of improved gauge actions. Possible origins of the phase transition is discussed.

   hep-latPRD(2005)·40 citations
2. 02*

   Positivity and topology in lattice gauge theory

   Michael Creutz🇺🇸

   The admissibility condition usually used to define the topological charge in lattice gauge theory is incompatible with a positive transfer matrix.

   hep-latPRD(2004)·25 citations
3. 03*

   Staggered Chiral Perturbation Theory at Next-to-Leading Order

   Stephen R. Sharpe🇺🇸 · Ruth S. Van de Water🇺🇸

   We study taste and Euclidean rotational symmetry violation for staggered fermions at nonzero lattice spacing using staggered chiral perturbation theory. We extend the staggered chiral Lagrangian to O(a^2 p^2), O(a^4) and O(a^2 m), the orders necessary for a full next-to-leading order calculation of pseudo-Goldstone boson masses and decay constants including analytic terms. We then calculate a number of SO(4) taste-breaking quantities, which involve only a small subset of these NLO operators. We predict relationships between SO(4) taste-breaking splittings in masses, pseudoscalar decay constants, and dispersion relations. We also find predictions for a few quantities that are not SO(4) breaking. All these results hold also for theories in which the fourth-root of the fermionic determinant is taken to reduce the number of quark tastes; testing them will therefore provide evidence for or against the validity of this trick.

   hep-latPRD(2005)·85 citations
4. 04*

   RG Decimations and Confinement

   E. T. Tomboulis🇺🇸

   We outline the steps in a derivation of the statement that the SU(2) gauge theory is in a confining phase for all values of the coupling, $0<\beta <\infty$, defined at lattice spacing a. The approach employed is to obtain both upper and lower bounds for the partition function and the `twisted' partition function in terms of approximate decimation transformations. The behavior of the exact quantities is thus constrained by that of the easily computable bounding decimations.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·1 citation
5. 05*

   $Re(A_0)$, $Re(A_2)$ and RG evolution for $N_f=3$

   Keunsu Choi🇰🇷 · Weonjong Lee🇰🇷

   We present results of $Re(A_0)$ and $Re(A_2)$ calculated using HYP staggered fermions on the lattice of $16^3\times 64$ at $\beta =6.0$. These results are obtained using leading order chiral perturbation in quenched QCD. Buras's original RG evolution matrix develops a removable singularity for $N_f=3$. This subtlety is resolved by finding a finite solution to RG equation and the results are presented.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
6. 06*

   Theta vacuum effects on the pseudoscalar condensates and the eta^prime meson in 2-dimensional lattice QED

   Hidenori Fukaya🇯🇵 · Tetsuya Onogi🇯🇵

   We study the chiral condensates and the eta^prime meson correlators of the massive Schwinger model in non-zero theta vacuum. Our data suggest that the pseudoscalar operator does condense in a fixed topological sector and gives long range correlations of the eta^prime meson. We find that this is well understood from the clustering decomposition and statistical picture. Our result also indicates that even in theta=0 case, the long range correlation of eta^prime meson receives non-zero contributions from all the topological sectors and that their cancellation is non-trivial and requires accurate measurement of the reweighting factors as well as the expectation values. It is then clear that the fluctuation of the disconnected diagram originates from the pseudoscalar condensates.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·0 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.