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Isospin mixing and Fermi transitions: Selfconsistent deformed mean field calculations and beyond

R. Alvarez-Rodriguez·E. Moya de Guerra·P. Sarriguren
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Abstract

We study Fermi transitions and isospin mixing in an isotopic chain 70-78 Kr considering various approximations that use the same Skyrme-Hartree-Fock single particle basis. We study Coulomb effects as well as the effect of BCS and quasiparticle random phase approximation (QRPA) correlations. A measure of isospin mixing in the approximate ground state is defined by means of the expectation value of the isospin operator squared in N=Z nuclei (which is generalized to N different from Z nuclei). Starting from strict Hartree-Fock approach without Coulomb, it is shown that the isospin breaking is negligible, on the order of a few per thousand for (N-Z)=6, increasing to a few percent with Coulomb. Pairing correlations induce rather large isospin mixing and Fermi transitions of the forbidden type (beta- for N Z). The enhancement produced by BCS correlations is compensated to a large extent by QRPA correlations induced by isospin conserving residual interactions that tend to restore isospin symmetry.

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R. Alvarez-Rodriguez, E. Moya de Guerra, P. Sarriguren. 2005-02-28. Isospin mixing and Fermi transitions: Selfconsistent deformed mean field calculations and beyond. https://doi.org/10.1103/physrevc.71.044308

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