  We investigate Thirring-like models containing fermionic and scalar fields
propagating in 2-dimensional space time. The corresponding conformal algebra is
studied and we disprove a conjecture relating the finite size effects to the
central charge. Some new results concerning the fermionic determinant on the
torus with chirally twisted boundary conditions and a chemical potential are
presented. In particular we show how the thermodynamics of the Thirring model
depends on the current-current interaction.
