The IBM description of the b(E2) anomaly: Dynamical triaxiality and configuration mixing

A theoretical investigation has been carried out to examine the effects of dynamical triaxility and configuration mixing on the $B\left(E2\right)$ anomaly, characterized by $B_{4/2}=B(E2;4_1^{+}\to 2_1^{+})/B(E2;2_1^{+}\to 0_1^{+})<1.0$ and $R_{4/2}=E\left(4_1^{+}\right)/E\left(2_1^{+}\right)\ge 2.0$, within the framework of the interacting boson model (IBM). The results indicate that the effective γ deformation may undergo substantial changes with increasing angular momentum in the $B\left(E2\right)$ anomaly system governed by an IBM Hamiltonian involving rotor-like terms. Further calculations reveal that mixing between normal and intruder states may facilitate the emergence of $B\left(E2\right)$ anomaly, thereby providing additional theoretical insights into this unusual phenomenon.