Pentaquark baryons in quenched lattice QCD with exact chiral symmetry
نویسندگان
چکیده
We investigate the mass spectrum of pentaquark baryons in quenched lattice QCD with exact chiral symmetry. Using interpolating operators based on the diquark-diquark-antiquark picture in the Jaffe-Wilzcek model, we measure time correlation functions for 70 gauge configurations generated with Wilson gauge action at β = 6.1 on the 203 × 40 lattice, and extract the masses of even and odd parity states respectively. With the pion decay constant (fπa) extracted from the pion correlation function, and the experimental input fπ = 132 MeV, we determine the inverse lattice spacing a−1 = 2.21(3) GeV. By chiral (linear) extrapolation to the pion mass mπ = 135 MeV, we determine the masses of lowest lying pentaquark baryons (JΠ = 1/2+): mN ([ud][ud]d̄) = 1460(51) MeV, mΘ([ud][ud]s̄) = 1539(95) MeV, and mΞ([ds][ds]ū) = 1826(87) MeV. Our results suggest that the parity of Θ+(1540) and Ξ 3/2(1860) is even, and N([ud][ud]d̄) can be identified with the Roper resonance N(1440)P11 . PACS numbers: 11.15.Ha, 11.30.Rd, 12.38.Gc
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