Dipole excited states in 11Li with complex scaling

Abstract

The 1 − excitations of the three-body halo nucleus 11Li are investigated. We use adiabatic hyperspherical expansion and solve the Faddeev equations in coordinate space. The method of complex scaling is used to compute the resonance states. The Pauli forbidden states occupied by core neutrons are excluded by constructing corresponding complex scaled phase equivalent two-body potentials. We use a recently derived neutron–core interaction consistent with known structure and reaction properties of 10Li and 11Li. The computed dipole excited states with J π =1/2 +, J π =3/2 +, and J π =5/2 + have energies ranging from 0.6 to 1.0 MeV and widths between 0.15 and 0.65 MeV. We investigate the dependence of the complex energies of these states on the 10Li spectrum. The finite spin-3/2 of the core and the resulting core–neutron spin–spin interaction are important. The connection with Coulomb dissociation experiments is discussed and a need for better measurements is pointed out.