A pentaquark model for Lambda(1405)
  We study a pentaquark model of the negative parity hyperon Lambda(1405). We choose a specific quark configuration for trial, and use the perturbative chiral quark model extended to four quarks and one anti-quark system. We calculate a sigma-term and a scalar form factor of the hyperon and demonstrate their usefulness to study the nature of the hyperon. 
Takahi Inoue