Four- and three-body dynamics in ⁶Li scattering

We apply a four-body version of the continuum-discretized coupled-channels method (four-body CDCC) to ⁶Li elastic scattering and investigate four-body dynamics (n + p +α+ T, where T is a target). Four-body CDCC reproduces the measured cross sections without introducing any adjustable parameter for ⁶Li + ²⁰⁹Bi scattering at 24-50 MeV and ⁶Li + ²⁰⁸Pb scattering at 29-210 MeV. We confirm that ⁶Li breakup effects are important in a wide energy range, and then focus on the competition between four-body (⁶Li+T ↔ n+p+α+T) and three-body (⁶Li+T↔ d +α+ T) channel-couplings. As an interesting property, we find that ⁶Li is mainly broken up into two particles d and α, and hardly into three particles n, p and α during scattering. This property is now called "dα-dominance". Following the dα-dominance, we propose an effective three-body model that simulates four-body CDCC calculations reasonably well.