Pentaquark baryon in anisotropic lattice QCD

Journal Article · Tue Feb 01 00:00:00 EST 2005 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.71.034001· OSTI ID:20705919

Ishii, N; Iida, H; Oka, M; Suganuma, H ^[1]; Doi, T ^[2]; Okiharu, F ^[3]

---

1. Department of Physics, H-27, Faculty of Science, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan)
2. RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States)
3. Department of Physics, Faculty of Science and Technology, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda, Tokyo 101-8308 (Japan)

The pentaquark (5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized anisotropy a{sub s}/a{sub t}=4 for a high-precision mass measurement. The standard Wilson action at {beta}=5.75 and the O(a) improved Wilson quark action with {kappa}=0.1210(0.0010)0.1240 are employed on a 12{sup 3}x96 lattice. Contribution of excited states is suppressed by using a smeared source. We investigate both the positive- and negative-parity 5Q baryons with I=0 and spin J=1/2 using a non-NK-type interpolating field. After chiral extrapolation, the lowest positive-parity state is found to have a mass, m{sub 5Q}=2.25 GeV, which is much heavier than the experimentally observed {theta}{sup +}(1540). The lowest negative-parity 5Q state appears at m{sub 5Q}=1.75 GeV, which is near the s-wave NK threshold. To distinguish spatially-localized 5Q resonances from NK-scattering states, we propose a new general method imposing a ''Hybrid Boundary Condition (HBC),'' where the NK threshold is artificially raised without affecting compact five-quark states. The study using the HBC method shows that the negative-parity state observed on the lattice is not a compact 5Q state but an s-wave NK-scattering state.

• OSTI ID: 20705919
• Journal Information: Physical Review. D, Particles Fields, Vol. 71, Issue 3; Other Information: DOI: 10.1103/PhysRevD.71.034001; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANISOTROPY
BAG MODEL
BARYONS
BOUNDARY CONDITIONS
CHIRAL SYMMETRY
CHIRALITY
EXCITED STATES
EXTRAPOLATION
GEV RANGE
ISOSPIN
KAON-NUCLEON INTERACTIONS
KAONS
LATTICE FIELD THEORY
PARITY
QUANTUM CHROMODYNAMICS
QUARKS
RENORMALIZATION
RESONANCE PARTICLES
REST MASS
S WAVES
SCATTERING
SPIN