TOTAL GAMOW-TELLER STRENGTH, GROUND-STATE CORRELATIONS AND SUM-RULES IN QRPA WITH NEUTRON-PROTON PAIRING

The sum of the Gamow-Teller (GT) strength in 1p0f shell nuclei is inve stigated by the Quasi-particle Random Phase Approximation (QRPA), wher e BCS and RPA ground-state correlations are included with proton-proto n and neutron-neutron but in addition also with neutron-proton (np) pa iring correlations. Two sums of GT strength with and without closure f or the intermediate excited states are derived including different app roaches for the ground-state correlations. The sum of the GT strength is compared to the available experimental data and other theoretical c alculations. The total GT strength in the usual BCS scheme is reduced by additional neutron-proton (np) pairing correlations. The usual RPA ground-state correlations reduce the total GT strength estimated from the BCS approximation while RPA with np pairing correlations yields an appreciably smaller reduction. Finally, ground-state correlations bey ond RPA are also shown to reduce the total GT strength.