  We consider the Gross-Neveu model with a continuous chiral symmetry in two
and three spacetime dimensions at zero and finite temperature. In order to
study long-range phase coherence, we construct an effective low-energy
Lagrangian for the phase $\theta$. This effective Lagrangian is used to show
that the fermionic two-particle correlation function at finite temperature
decays algebraically in 2+1 dimensions and exponentially in 1+1 dimensions.
