Light hadron spectroscopy in two-flavor QCD with small sea quark masses
- Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan)
- Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan)
- High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan)
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)
- Department of Physics, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
We extend the study of the light hadron spectrum and the quark mass in two-flavor QCD to smaller sea quark mass, corresponding to m{sub PS}/m{sub V}=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 m{sub PS}/m{sub V}=0.80-0.55. Whereas fits with either polynomial or continuum chiral perturbation theory (ChPT) fail, the Wilson ChPT (WChPT) that includes a{sup 2} 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 m{sub PS}/m{sub V} > or approx. 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%, m{sub ud}{sup MS-bar}({mu}=2 GeV)=3.11(17) [MeV] in the continuum limit.
- OSTI ID:
- 20705360
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 70, Issue 7; Other Information: DOI: 10.1103/PhysRevD.70.074503; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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B QUARKS
BARYON SPECTROSCOPY
C QUARKS
CHIRAL SYMMETRY
CHIRALITY
COMPUTERIZED SIMULATION
D QUARKS
EXTRAPOLATION
FLAVOR MODEL
GEV RANGE
LATTICE FIELD THEORY
MASS FORMULAE
MASS SPECTRA
MESON SPECTROSCOPY
MEV RANGE
PERTURBATION THEORY
QUANTUM CHROMODYNAMICS
RENORMALIZATION
REST MASS
RHO-770 MESONS
SYMMETRY BREAKING
T QUARKS
U QUARKS