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Giant Gamow-Teller resonances

The repulsive interaction between proton particles and neutron holes in the $J^{\pi}=1^+$ (spin-isospin) channel gives rise to a giant charge-exchange resonance in all nuclei with excess neutrons. The centroid of the resonance (which typically has a width of 5-10 MeV) can be roughly parameterized by the simple formula $E_{\rm GT} - E_{\rm F} = 26 A^{-1/3} - 18.5 (N-Z) A^{-1}$, where $E_{\rm F}$ is the centroid of the Fermi resonance [44]. This formula, however, captures only average behavior; individual cases depend on single-particle structure, and in particular the spin-orbit splitting.

The ability to model GT resonances is crucial for predictions of nuclear $\beta$ decay. Just as the low-lying E1 strength is depleted by the giant dipole resonance, so the low-lying GT strength, responsible for $\beta$ decay, is affected by the GT resonance. Since one of our future goals is an improved calculation of $\beta$-decay rates in nuclei along the r-process path, it is important to develop a reliable description of the GT giant resonance.

Jacek Dobaczewski