QUANTIZATION OF NONSTANDARD HAMILTONIAN-SYSTEMS

The quantization of classical theories that admit more than one Hamilt onian description is considered. This is done from a geometrical viewp oint, both at the quantization level (geometric quantization) and at t he level of the dynamics of the quantum theory. A spin-1/2 system is t aken as an example in which all the steps can be completed. It is show n that the geometry of the quantum theory imposes restrictions on the physically allowed non-standard quantum theories.