Anisotropic lattice QCD study of pentaquark baryons in spin 3/2 channel
  We perform the comprehensive analysis of the pentaquark (5Q) in J^P=3/2^{\pm} channel using anisotropic quenched lattice QCD. We employ the standard Wilson gauge action at \beta=5.75 and the O(a) improved Wilson (clover) quark action on a 12^3*96 lattice with the renormalized anisotropy as a_s/a_t = 4. A large number of gauge configurations as Nconf=1000 is analyzed, which is found to be essential to achieve a reliable measurement. We study three types of the Rarita-Schwinger intepolationg fields with I=0: (a) the NK*-type, (b) the (color-)twisted NK*-type, (c) a diquark-type. As a result, we find only massive states as m(5Q)= 2.1-2.2 GeV in J^P=3/2^- channel, and m(5Q) = 2.4-2.6 GeV in J^P=3/2^+ channel in the chiral limit. The analysis with the hybrid boundary condition (HBC) is performed to distinguish whether these resonances are compact 5Q resonances or two-particle scattering states. No low-lying compact 5Q resonance states are found below 2.1GeV. 
Takumi Doi (RIKEN BNL), Noriyoshi Ishii (Tokyo Inst. Tech.), Yukio   Nemoto (Nagoya Univ.), Makoto Oka (Tokyo Inst. Tech.), ...