Study of Yb isotopes with the coherent state formalism

Abstract

Coherent state approach (CSA) is applied to the interacting boson model (IBM) in the rotational region. States of the [Formula: see text] particle system are built up in a most general form as a function of the shape parameters [Formula: see text] and [Formula: see text]. The parameter [Formula: see text] occurring in the quadrupole operator which determines the degree of the [Formula: see text]-softness is taken to be varying with the boson number. The excitation energy equations are formed by using the moment of inertia of a rotating system which is obtained from the solution of the cranking problem. For each isotope, the deformation parameter is found by minimizing the ground state energy equation. The results are used to fit the experimental excitation energy spectrum and the electric quadrupole transition ratios of Yb isotopes. It is found that CSA works well to predict the energy of the states up to [Formula: see text]. But the predictions about the electric quadrupole transitions are nearly [Formula: see text] times greater than the experimental data.