European Journal of Physics, vol.17, no.2, pp.82-84, 1996 (Scopus)
The partition function defined in the usual way is a gauge-dependent quantity. However, the ansatz of Bernard and Gross et al leaves it gauge invariant. We use this ansatz for the partition function to show that Lagrange multipliers (non-physical bosonic fields) are not restricted to satisfying any boundary conditions in the path integral at finite temperature. We take a quantum mechanical model to illustrate that boundary conditions satisfied by non-physical fields depend on the choice of 'gauge'.