ΣNN quasibound states in 3He( K-, π∓) reactions at 600 MeV/c

We theoretically demonstrate the inclusive and semiexclusive spectra in the He-3( K-, pi(+)) reactions at 600 MeV/c (4 degrees) within a distorted-wave impulse approximation, using a coupled (2N - A) + (2N - Sigma) model with a spreading potential. We present the possible existence of the Sigma NN quasibound state with J(pi) = 1/2(+), T similar or equal to 1 near the Sigma threshold, predicted by a 2N - Y folding-model potential derived from YN g-matrices. The result shows that a signal of the 3(Sigma) He quasibound state is clearly confirmed near the Sigma threshold in the pi(-) spectrum, whereas a peak of the 3(Sigma)n n quasibound state is rather reduced in the pi(+) spectrum owing to the interference effects caused by the (3)S1- (1)S0 admixture in the NN pair. The mechanism of Sigma production for these spectra and charge symmetry breaking effects are also discussed.