Neutron-proton pairing and double-beta decay in algebraic models

Nuclear models based on Lie algebras provide insight into collective phenomena. Here neutron-proton pairing, which plays an important role in double beta decay, is discussed in two such models, one based on SO(5) and the second on SO(8). The latter model is used to test the accuracy of the Quasiparticle Random Phase Approximation and improvements to it. Presented at Workshop on calculation of double-beta-decay matrix elements (MEDEX’97), Prague, May 27–31, 1997. This work was supported in part by the U.S. Department of Energy under Grant DE-FG02-97ER41019.