Dipole excited states in 11Li with complex scaling

The 1(-) excitations of the three-body halo nucleus Li-11 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 Li-10 and Li-11. The computed dipole excited states with J(pi) = 1/2(+), J(pi) = 3/2(+), and J(pi) = 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 IOU 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. (C) 2002 Elsevier Science B.V All rights reserved.