Multichannel theory of the 0+ resonance in 4He

In the framework of the algebraic version of the resonating group method, the states of the 4He continuous spectrum lying between the thresholds of the p+3H and n+3He channels have been studied. The theory of the singlet O+ resonance belonging to this range is presented: the main factors are found, which produce the resonance, the resonance parameters are calculated, the probabilities of the monopole transitions from the 4He ground state to the continuum spectrum states corresponding to the interthreshold range are found, and the p3H and n3He scattering lengths are evaluated