Inverted signature dependence of B(M1) in natural-parity rotational bands

The conditions for occurrence of the ‘‘inverted’’ signature dependence of B(M1), that is, the enhancement of transitions from the unfavored states, in natural-parity rotational bands are discussed based on the rotating shell model. An example of coexistence of the inverted and the normal signature dependence in an axially symmetric nucleus due to the change in $g_{\mathrm{RPA}}$ associated with the band crossing is presented.