ar X iv : 0 70 7 . 40 44 v 1 [ he p - ph ] 2 7 Ju l 2 00 7 1 Four - and Five - Body Scattering Calculations of Exotic Hadron Systems

We study the five-quark system uudds̄ in the standard non-relativistic quark model by solving the scattering problem. Using the Gaussian Expansion Method (GEM), we perform the almost precise multi-quark calculations by treating a very large five-body modelspace including the NK scattering channel explicitly. Although a lot of pseudostates (discretized continuum states) with J = 1 2 ± and J = 3 2 ± are obtained within the bound-state approximation, all the states in 1.4 − 1.85 GeV in mass around Θ(1540) melt into non-resonant continuum states through the coupling with the NK scattering state in the realistic case, i.e., there is no five-quark resonance below 1.85GeV. Instead, we predict a five-quark resonance state of J = 1 2 − with the mass of about 1.9GeV and the width of Γ ≃ 2.68MeV. Similar calculation is done for the four-quark system cc̄qq̄ (q = u, d) in connection with X(3872).