The ground and even-parity excited states and the scattering problem of the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ system are examined within the framework of the (2N+2N) and (1N+3N) cluster-coupling model with the specific distortion effect of the deuteron cluster taken into consideration. Calculations are performed by a multichannel resonating-group method using an effective nucleon-nucleon (NN) potential similar to that adopted in p+α, d+α, ${}_{}{}^3{}_{}{}^{}\mathrm{H}$+α (or ${}_{}{}^3{}_{}{}^{}\mathrm{He}$+α), and α+α systems. The results show that, because of the high compressibility of the deuteron cluster and the similarity in threshold energies for the 2N+2N and 1N+3N configurations, both the distortion effect and the channel-coupling effect are important in this system. When the 1N+3N configuration is included in the calculation, the deuteron-distortion effect turns out to be significantly weakened, owing to the fact that the 1N+3N configuration is energetically the most favored one. In addition, it is shown that such a specific distortion effect is quite small in the channel spin S=2 state of d+d scattering. With the full calculation including the distortion effect, it is found possible to reproduce well the energies of the ground state and the first-excited $0^{+}$ state; the differential cross sections for d+d, p+t, and n+h elastic scattering; the polarizations for p+t and n+h scattering; and the cross sections for ${}_{}{}^1{}_{}{}^{}\mathrm{H}$(t,n${)}^3$He and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(p,d${)}^2$H reactions.

• Received 10 January 1986

DOI:https://doi.org/10.1103/PhysRevC.34.22