Spin-dipole strength functions of 4He with realistic nuclear forces

Both isoscalar and isovector spin-dipole excitations of ⁴He are studied using realistic nuclear forces in the complex scaling method. The ground state of ⁴He and discretized continuum states with J^π=0^-,1^-,2^- for A=4 nuclei are described in explicitly correlated Gaussians reinforced with global vectors for angular motion. Two- and three-body decay channels are specifically treated to take into account final state interactions. The observed resonance energies and widths of the negative-parity levels are all in fair agreement with those calculated from both the spin-dipole and electric-dipole strength functions as well as the energy eigenvalues of the complex scaled Hamiltonian. Spin-dipole sum rules, both non-energy-weighted and energy-weighted, are discussed in relation to tensor correlations in the ground state of ⁴He.