Centrifugal stretching of ¹⁷⁰Hf in the interacting boson model

We present the results of a recent experiment to deduce lifetimes of members of the ground state rotational band of ¹⁷⁰Hf, which show the effect of centrifugal stretching in this deformed isotope. Results are compared to the geometrical confined beta-soft (CBS) rotor model, as well as to the interacting boson model (IBM). Experimental data are in good agreement with the CBS predictions of centrifugal stretching but disagree with IBM-based calculations. We show that this disagreement can be corrected by either using a large-N version of the model, or by effectively correcting finite-N effects where N is the number of valence bosons taken into account by the model