M1 transitions between low-lying states in the SU(3) limit of the IBM-2

Magnetic dipole transitions between low-lying states in deformed even–even nuclei are studied in the framework of the neutron–proton interacting boson model. To obtain the nonvanishing M1 transitions between low-lying states, the proton–neutron quadrupole interaction is added to the dynamical symmetric SU(3) Hamiltonian as a perturbed term, which breaks F-spin symmetry. We introduce the expansion method which is similar to the intrinsic state formalism of the collective model to determine the matrix elements of SU(3) generators and apply first-order perturbation theory to derive M1 matrix elements between the perturbed states. Analytic forms for M1 transition rates between low-lying collective states are obtained and a comparison with available B(M1) ratios in 154Gd is presented.

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