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Pentaquark baryon in anisotropic lattice QCD
Pentaquark baryon in anisotropic lattice QCD
Ishii, N.
Doi, T.
Iida, H.
Okiharu, F.
Copyright(C)2005 The American Physical Society
The pentaquark (5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized anisotropy as/at=4 for a high-precision mass measurement. The standard Wilson action at β=5.75 and the O(a) improved Wilson quark action with κ=0.1210(0.0010)0.1240 are employed on a 123×96 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, m5Q=2.25 GeV, which is much heavier than the experimentally observed Θ+(1540). The lowest negative-parity 5Q state appears at m5Q=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.
American Physical Society
2005-02
eng
journal article
http://hdl.handle.net/10191/30869
https://niigata-u.repo.nii.ac.jp/records/2328
info:doi/10.1103/PhysRevD.71.034001
AA00773624
15507998
Physical Review D
Physical Review D
71
034001
1
11
https://niigata-u.repo.nii.ac.jp/record/2328/files/71_034001_1-11.pdf
application/pdf
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2019-07-29