A microscopic benchmark-study of triaxiality in low-lying states of 76Kr

摘要

We report on a seven-dimensional generator coordinate calculation in the twodeformation parameters $eta$ and $gamma$ together with projection onthree-dimensional angular momentum and two particle numbers for the low-lyingstates in $^{76}$Kr. These calculations are based on covariant densityfunctional theory. Excellent agreement is found with the data for the spectrumand the electric multipole transition strengths. This answers the importantquestion of dynamic correlations and triaxiality in a fully microscopic way. Wefind that triaxial configurations dominate both the ground state and the quasi$gamma$-band. This yields a different picture from the simple interpretationin terms of "coexistence of a prolate ground state with an oblate low-lyingexcited state", which is based on the measured sign of spectroscopic quadrupolemoments. This study also provides for the first time a benchmark for thecollective Hamiltonian in five dimensions. Moreover, we point out that thestaggering phase of the $gamma$-band is not a safe signature for rigidtriaxiality of the low-energy structure.