The notion of shape invariance in supersymmetric quantum mechanics is examined in relation with the generalized oscillator algebra. Shape invariance is reformulated as fermion-number independence of a parameter function and seen as a symmetry under a shape-related parameter transformation. It is also shown how shape invariance is implied in the dynamical group approach.

We revisit via a path-integral approach the magnetic top proposed recently by Barut, Božić, and Marić. We point out that the magnetic top has the SU(2) symmetry and that it can be viewed as a free top seen from a rotating frame. We present an alternative path-integral quantization of the magnetic top on the basis of the symmetry, and show that the magnetic coupling does not participate in altering the spin quantum numbers.

The unified treatment of the Dirac monopole, the Schwinger monopole, and the Aharonov-Bohm problem by Barut and Wilson is revisited via a path integral approach. The Kustaanheimo-Stiefel transformation of space and time is utilized to calculate the path integral for a charged particle in the singular vector potential. In the process of dimensional reduction, a topological charge quantization rule is derived, which contains Dirac's quantization condition as a special case. “Everything that is made beautiful and fair and lovely is made (...) for the eye of one who sees.” Jelaluddin Rumi,Mathnawi [I, 2383]. (shrink)