- 著者
- Namekawa Y. Aoki S. Fukugita M. Ishikawa K.-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Lesk V. I. Okawa M. Ukawa A. Umeda T. Yoshié T.
- 出版者
- American Physical Society
- 雑誌
- Physical review D (ISSN:15507998)
- 巻号頁・発行日
- vol.70, no.7, pp.074503, 2004-10
- 被引用文献数
- 24 31
We extend the study of the light hadron spectrum and the quark mass in two-flavor QCD to smaller sea quark mass, corresponding to mPS/mV=0.60–0.35. Numerical simulations are carried out using the RG-improved gauge action and the meanfield-improved clover quark action at beta=1.8 (a=0.2 fm from rho meson mass). We observe that the light hadron spectrum for small sea quark mass does not follow the expectation from chiral extrapolations with quadratic functions made from the region of mPS/mV=0.80–0.55. Whereas fits with either polynomial or continuum chiral perturbation theory (ChPT) fail, the Wilson ChPT (WChPT) that includes a2 effects associated with explicit chiral symmetry breaking successfully fits the whole data: In particular, WChPT correctly predicts the light quark mass spectrum from simulations for medium heavy quark mass, such as mPS/mV>~0.5. Reanalyzing the previous data with the use of WChPT, we find the mean up and down quark mass being smaller than the previous result from quadratic chiral extrapolation by approximately 10%, mudMS-bar(µ=2 GeV)=3.11(17) [MeV] in the continuum limit.
- 著者
- Umeda T. Aoki S. Fukugita M. Ishikawa K.-I. Ishizuka N. Iwasaki Y. Kanaya K. Kuramashi Y. Lesk V. I. Namekawa Y. Okawa M. Taniguchi Y. Ukawa A. Yoshié T.
- 出版者
- American Physical Society
- 雑誌
- Physical review D (ISSN:05562821)
- 巻号頁・発行日
- vol.68, no.3, pp.034503, 2003-08
- 被引用文献数
- 15
We report on our study of two-flavor full QCD on anisotropic lattices using O(a)-improved Wilson quarks coupled with a renormalization-group-improved glue. The bare gauge and quark anisotropies corresponding to the renormalized anisotropy ξ=as/at=2 are determined as functions of β and κ, which cover the region of spatial lattice spacings as≈0.28–0.16 fm and mPS/mV≈0.6–0.9. The calibrations of the bare anisotropies are performed with the Wilson loop and the meson dispersion relation at four lattice cutoffs and 5–6 quark masses. Using the calibration results we calculate the meson mass spectrum and the Sommer scale r0. We confirm that the values of r0 calculated for the calibration using pseudoscalar and vector meson energy momentum dispersion relations coincide in the continuum limit within errors. This work serves to lay the groundwork for studies of heavy quark systems and the thermodynamics of QCD including the extraction of the equation of state in the continuum limit using Wilson-type quark actions.
- 著者
- Lesk V. I. Aoki S. Burkhalter R. Fukugita M. Ishikawa K.-I. Ishizuka N. Iwasaki Y. Kanaya K. Kuramashi Y. Okawa M. Taniguchi Y. Ukawa A. Umeda T. Yoshie T.
- 出版者
- American Physical Society
- 雑誌
- Physical review D (ISSN:05562821)
- 巻号頁・発行日
- vol.67, no.7, pp.074503, 2003-04
- 被引用文献数
- 16
We present results for the mass of the η′ meson in the continuum limit for two-flavor lattice QCD, calculated on the CP-PACS computer, using a renormalization-group-improved gauge action, and the Sheikoleslami-Wohlert fermion action with a tadpole-improved csw. The correlation functions are measured at three values of the coupling β corresponding to the lattice spacing a≈0.22, 0.16, 0.11 fm and for four values of the quark mass parameter κ corresponding to mπ/mρ≈0.8, 0.75, 0.7, 0.6. For each (β, κ) pair, 400–800 gauge configurations are used. The two-loop diagrams are evaluated using a noisy source method. We calculate η′ propagators using both smeared and local sources, and find that excited state contaminations are much reduced by smearing. A full analysis for the smeared propagators gives mη′=0.960(87)-0.248+0.036 GeV in the continuum limit, where the second error represents the systematic uncertainty coming from varying the functional form for chiral and continuum extrapolations.