Lattice study of pentaquark states

Abstract

We present a study of the pentaquark system in quenched lattice QCD using diquark-diquark and kaon-nucleon local and smeared interpolating fields. We examine the volume dependence of the spectral weights of local correlators on lattices of size 163×32, 243×32, and 323×64 at β=6.0. We find that a reliable evaluation of the volume dependence of the spectral weights requires accurate determination of the correlators at large time separations. Our main result from the spectral weight analysis in the pentaquark system is that within our variational basis and statistics we cannot exclude a pentaquark resonance. However, our data also do not allow a clear identification of a pentaquark state since only the spectral weights of the lowest state can be determined to sufficient accuracy to test for volume dependence. In the negative parity channel, the mass extracted for this state is very close to the kaon-nucleon threshold, whereas in the positive parity channel it is about 60% above. © 2006 The American Physical Society.