ON THE PATH-INTEGRAL REPRESENTATION FOR SPIN SYSTEMS

We propose a classical constrained Hamiltonian theory for the spin. Af ter the Dirac treatment we show that due to the existence of second-cl ass constraints the Dirac brackets of the proposed theory represent th e commutation relations for the spin. We show that the corresponding p artition function, obtained via the Fadeev-Senjanovic procedure, coinc ides with that obtained using coherent states. We also evaluate this p artition function for the case of a single spin in a magnetic field.