Delta-Hole Interaction in Nuclei and the Gamow-Teller Strength in ^90Nb

The recently obtained experimental result for the quenching of the GT sum rule in the reaction ^90Zr(p,n)^90Nb is used to extract the value of the Landau-Migdal parameter g_{N\Delta}', taking into account also the effect of the finite range meson exchange interactions. The extracted value is compared to the one obtained in the \pi+\rho exchange model by explicitly taking into account the effects of antisymmetrization and short range correlations. Although the \pi+\rho exchange model tends to give a somewhat stronger quenching than observed experimentally, the results are consistent within the experimental error bars if the quark model value for the parameter f_\Delta/f_\pi is used.