Interacting boson model microscopic theory

SAMBATARO Microscopic Theory of the Interacting Boson Model... 

The effect of neutron-proton symmetry breaking on the distribution of M1 strength in the SU(3) limit of the Interacting Boson Model (IBA-2) is studied. A possible alternative choice for the Majorana force is investigated, with a structure that resembles more closely that which is calculated in microscopic theories. It is found that the specific choice for the Majorana interaction has important consequences for the magnetic strength distribution function. In addition it allows for an alternative interpretation of the second excited K7T=0+ band in rare earth nuclei, as a mixed-symmetry state. 

The remaining important aspect is how to derive these properties from a microscopic theory. In this respect, particularly interesting is the interacting boson-fermion model described at this workshop by Micnas [23]. This model is an extension of the method discussed above to mixed systems of bosons and fermions [24]. A symmetry analysis of this system will be presented elsewhere. 

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