E0 transition strengths as a tool to constraint model parameters. Application to even-even Xe isotopes

Background: In any nuclear structure model, the accurate description of E0 transition rates constitutes a significant challenge; at the same time, these observables provide a stringent constraint on the admissible parameter space of the model. Purpose: This work pretend to study the value of certain $\rho^2(E0)$ values or ratios over the whole parameter space of the interacting boson model. As an application, the case of the even-even Xe isotopes will be explored. Method: The interacting boson model will be considered for the calculation of $\rho^2(E0)$ values for some key transitions and to explore how these observables change over the parameter space of the model. Results: Several key $\rho^2(E0)$ values or ratios are considered and contour plots in the parameter space of the interacting boson model (Casten triangle) are computed. The results for even-even Xe isotopes are superimposed on the contour plots. Conclusions: The presented analysis confirms that $\rho^2(E0)$ values and, in particular, certain ratios allow to constraint the parameter space of the interacting boson model. There are certain regions where the $\rho^2(E0)$ values cannot be altered by the fine tuning of the Hamiltonian parameters.