q-deformed vibrational limit of interacting boson model

Even-even near-spherical vibrational nuclei, with energy ratio R41+/21+ = E41+/E21+ in the range 2-2.5, are investigated within the framework of interacting boson model and q-deformed version of this model, using the U (5) dynamical symmetry. The parametrization of the U (5) Hamiltonian and q-deformed version are found leading to a description of energy spectra of 33 nuclei with a root mean square deviation from the experimental level energies less than 100 keV. The findings support the fact that we are very near to the critical point symmetries in the real q-deformed vibrational Hamiltonian.