Ab initio study of the Jπ=0± continuum structures in 4He.

The Jπ=0± continuum structures in 4He are investigated by using an ab initio reaction theory with the microscopic R-matrix method. In the Ex ≥~20 MeV excitation energy region of 4He, the continuum states are mainly described by the t+p, h+n, and d+d channels. The Jπ=0± elastic phase shifts of the t+p and h+n channels show an apparently resonant behavior which might indicate the existence of excited 0+3 and 0-2 resonance states of 4He above the known 0+2 and 0-1 ones. However, the corresponding 0+3 and 0-2 resonances have not been observed yet, although an experimental candidate with a large decay width is reported for 0-2. In this paper, by analyzing the Jπ=0±S matrices, we discuss why the observation of these states is unlikely. [ABSTRACT FROM AUTHOR]