Delta-hole interaction in nuclei and the Gamow-Teller strength in Nb-90

The recently obtained experimental result for the quenching of the GT sum r ule in the reaction Zr-90(p,n)Nb-90 is used to extract the value of the Lan dau-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 + p exchange model by explicitly taking into account the effects of antisymmetrization and short range correlations. Alt hough the pi + p exchange model tends to give a somewhat stronger quenching than observed experimentally, the results are consistent within the experi mental error bars if the quark model value for the parameter f(Delta)/f(pi) is used. (C) 2001 Published by Elsevier Science B,V.