Comparative Study of Three-Body Models for Continuum States

Abstract

We discuss properties of three-body continuum states in the hyperspherical formalism. The associated coupled-channel system is solved on a Lagrange basis, and is complemented by the R-matrix theory for the treatment of scattering states. Three-body α + n + n phase shifts are determined under various conditions. Two approximations of the continuum are considered: the complex scaling and the pseudostate methods. Both are briefly outlined, and compared with the R-matrix approach for the dipole-strength distribution of 6 He. A fair agreement is obtained between the three methods. We also discuss the influence of the α + n and n + n interactions, as well as the effect of the Pauli principle. Some differences are obtained, but all calculations predict a broad 1 − resonance near 1 MeV. §1.

Electric multipole response of the halo nucleus 6He

“…While most theoretical studies have been focused on dipole strength [45,55,56], our includes many more multipolarities. In order to compare our approach with others, we have also performed a set of calculations for dipole response from ground state to all components of 1 − state.…”

Analytical transformed harmonic oscillator basis for three-body nuclei of astrophysical interest: Application to6He

“…When the continuum states are not available, it is considered that, in general, a PS with energy ε n is the superposition of continuum states in the vicinity. There are several ways to assign an energy distribution to a PS [44,45]. In this work, for each discrete value of B(Eλ)(ε n ), a Poisson distribution D(ε, ε n , w) with the following form is assigned,…”

High precision studies of soft dipole mode in two-neutron halo nuclei: $^{6}$He case

“…The soft dipole excitations of 6 He were studied theoretically by different methods [3][4][5][6][7][8][9][10][11]. Shortcomings of these studies will be discussed later in present paper.…”