Gamow-Teller strength at high excitations

A perturbative calculation is reported for the mixing of Gamow-Teller strength with two-particle two-hole configurations at high excitation energies. We find that roughly 50% of the Gamow-Teller strength is shifted into the region of 10-45 MeV excitation for the nucleus ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$. This would explain a substantial part of the continuum background seen in the 200 MeV ($p, n$) reaction.