Spin isospin responses in nuclei and their unified understanding with Landau-Migdal parameters

Both the Gamow-Teller (GT) and the pionic response functions are investigated in the same framework of the continuum random phase approximation with the π ρ + g′ model interaction. The Landau-Migdal (LM) parameters, g′_NN and g′_NΔ, are estimated by comparing these calculations with recent experimental data. The peak of the GT resonance and the pionic response functions below the quasielastic scattering (QES) peak constrain g′_NN, whereas the quenching of the GT total strength and the enhanced pionic strength around the QES peak provide information about g′_NΔ. We obtain a common set of the LM parameters, g′_NN = 0.6-0.7 and g′_NΔ = 0.2-0.4, which reproduce the peak and quenching of the GT strengths as well as the enhancement of the pionic modes. The g′_NΔ value is significantly smaller than g′_NN, which means that the universality ansatz, g′_NN = g′_NΔ, should not be valid.