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RESEARCH PRODUCT

Gamow-Teller response in the configuration space of a density-functional-theory–rooted no-core configuration-interaction model

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Background: The atomic nucleus is a unique laboratory in which to study fundamental aspects of the electroweak interaction. This includes a question concerning in medium renormalization of the axial-vector current, which still lacks satisfactory explanation. Study of spin-isospin or Gamow-Teller (GT) response may provide valuable information on both the quenching of the axial-vector coupling constant as well as on nuclear structure and nuclear astrophysics.Purpose: We have performed a seminal calculation of the GT response by using the no-core configuration-interaction approach rooted in multireference density functional theory (DFT-NCCI). The model treats properly isospin and rotational symmetries and can be applied to calculate both the nuclear spectra and transition rates in atomic nuclei, irrespectively of their mass and particle-number parity.Methods: The DFT-NCCI calculation proceeds as follows: First, one builds a configuration space by computing relevant, for a given physical problem, (multi)particle-(multi)hole Slater determinants. Next, one applies the isospin and angular-momentum projections and performs the isospin and $K$ mixing in order to construct a model space composed of linearly dependent states of good angular momentum. Eventually, one mixes the projected states by solving the Hill-Wheeler-Griffin equation.Results: The method is applied to compute the GT strength distribution in selected $N\ensuremath{\approx}Z$ nuclei including the $p$-shell $^{8}\mathrm{Li}$ and $^{8}\mathrm{Be}$ nuclei and the $sd$-shell well-deformed nucleus $^{24}\mathrm{Mg}$. In order to demonstrate a flexibility of the approach we present also a calculation of the superallowed GT $\ensuremath{\beta}$ decay in doubly-magic spherical $^{100}\mathrm{Sn}$ and the low-spin spectrum in $^{100}\mathrm{In}$.Conclusions: It is demonstrated that the DFT-NCCI model is capable of capturing the GT response satisfactorily well by using a relatively small configuration space, exhausting simultaneously the GT sum rule. The model, due to its flexibility and broad range of applicability, may either serve as a complement or even as an alternative to other theoretical approaches, including the conventional nuclear shell model.