Structure and decay width of the in a one-gluon exchange model

Abstract

The mass and decay width of the Θ + (1540) with isospin 0 are investigated in a constituent quark model comprising uudds quarks. The resonance state for the Θ + is identified as a stable solution in correlated basis calculations. With the use of a one-gluon exchange quark-quark interaction, the mass is calculated to be larger than 2 GeV, increasing in order of the spin-parity, 1 2 − , 3 2 − and 1 2 + ( 3 2 + ), and only the 3 2 − state has a small width to the nK * + decay. If the calculated mass is shifted to around 100 MeV above the N +K threshold, the Θ + (1540) is possibly 1 2 + ( 3 2 + ) or 3 2 − , though in the latter case it cannot decay to the nK + channel. In addition it is conjectured that other pentaquark state with different spin-parity exists below the Θ + (1540). The structure of the Θ + is discussed through the densities and two-particle correlation functions of the quarks and through the wave function decomposition to a baryon-meson model and a diquark-pair model.