The Landau-Migdal parameters, g′NN and g′NΔ

The Landau-Migdal parameters, g''s, for nucleon-nucleon and nucleon-Delta couplings are estimated from recent experimental data on the giant Gamow-Teller state of Nb-90. The observed quenching of the GT strength by 10% provides 0.12 < g'(N Delta) < 0.23 for g'(Delta Delta) < 1.0. Since g'(Delta N) is thus small, the excitation energy is dominated by g'(NN), which is estimated to be about 0.59. The universality ansatz for g"s cannot reproduce the excitation energy and strength simultaneously. The results are obtained ignoring the systematic uncertainties in the experiment which are unknown at present. 1999 Published by Elsevier Science B.V. All rights reserved.