Pairing Phase Transition in Small Particles

A formulation of the pairing phase transition is presented which takes into account both thermal and quantal fluctuations, within the framework of the static path approximation with quadratic corrections. The theory is applied to the study of small superconducting particles, where it provides an overall account of the experimental findings. It is shown that the phase transition is well accounted for in the static path approximation, while the quadratic corrections are significant only for very small particles.