The rapid transition between spherical and $\gamma$-soft shapes in Ba and Xenuclei in the mass region $A \geq 130$ is analyzed using excitation spectra andcollective wave functions obtained by diagonalization of a five-dimensionalHamiltonian for quadrupole vibrational and rotational degrees of freedom, withparameters determined by constrained self-consistent relativistic mean-fieldcalculations for triaxial shapes. The results reproduce the characteristicevolution of excitation spectra and E2 transition probabilities and, ingeneral, a good agreement with available data is obtained. The calculatedspectra display fingerprints of a second-order shape phase transition that canapproximately be described by analytic solutions corresponding to the E(5)dynamical symmetry.
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机译：使用激发光谱和通过将五维哈密顿量对角化获得的四极杆振动和旋转度的激发波和集体波函数，分析了质量域$ A \ geq 130 $中Ba和Xenuclei中球形和$ \ gamma $软形状之间的快速过渡。自由度，其参数由三轴形状的受约束的自洽相对论平均场计算确定。结果再现了激发光谱和E2跃迁概率的特征演化，并且总体上与可获得的数据具有良好的一致性。计算得到的光谱显示第二阶形状相变的指纹，可以通过对应于E（5）动力学对称性的解析解来描述。
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