Mean field theory of effective spin models as a baryon fugacity expansion
Mean field theory of effective spin models as a baryon fugacity expansion
The free energy of effective spin or ``Polyakov line'' models with a chemical potential, based on the $\mathrm{U}(N)$ group, does not depend on the chemical potential. In a mean field-inspired expansion, we show how the condition of unit determinant, taking $\mathrm{U}(N)$ to $\mathrm{SU}(N)$, reintroduces the chemical potential, and allows us …