标题： B(M1,0+ -> 1+)强度的IBM-3和IBM-4求和规则 显示英文标题

标题： Sum Rules for B(M1,0+ -> 1+) Strength in IBM-3 and IBM-4

摘要： 对于偶-偶核，在IBM、IBM-3和IBM-4的同位旋不变形式中，导出了$B(M1,0^+_1\rightarrow1^+_i)$强度的求和规则，在这种情况下，相应的自然内部对称性，同位旋$U$(3)和$U(6)\supset SU$(4)是守恒的。 随后，总强度被分解为允许的同位旋的分量部分和（以及IBM-4中的$SU(4)$表示）。 在通常的IBM动力学对称性也有效的情况下，给出了所有$B(M1,0^+_1\rightarrow1^+_i)$的完整描述。 与IBM-2不同的是，在动力学对称性情况下，对于$T\neq 0$，在IBM-3中分裂为两个状态，在IBM-4中分裂为三个状态。 在扩展版本的基态中存在$pn$玻色子，这降低了预期强度，使其相对于 IBM-2 的情况有所减少，从而原则上有可能利用某个核的$B(M1)$数据来推断哪种版本最为合适。 显示英文摘要

摘要： Sum rules for $B(M1,0^+_1\rightarrow1^+_i)$ strength are derived for even-even nuclei in the isospin-invariant forms of the IBM, IBM-3 and IBM-4, in the cases where the respective natural internal symmetries, isospin $U$(3) and $U(6)\supset SU$(4), are conserved. Subsequently, the total strength is resolved into its component partial sums to the allowed isospins (and $SU(4)$ representations in IBM-4). In cases where the usual IBM dynamical symmetries are also valid, a complete description of all $B(M1,0^+_1\rightarrow1^+_i)$ is given. In contrast to IBM-2, there is fragmentation of the strength even in the dynamical symmetry cases, for $T\neq 0$, over two states in IBM-3, and over three states in IBM-4. The presence of $pn$ bosons in the ground state of the extended versions reduces the expected strength from that for IBM-2, allowing in principle the possibility of using $B(M1)$ data for a given nucleus to infer which version is the most appropriate.