  In this work we study different variations of the MIT bag model. We start
with the so called non-ideal bag model and discuss it in detail. Then we
implement a vector interaction in the MIT bag model that simulates a meson
exchange interaction and fix the quark-meson coupling constants via symmetry
group theory. At the end we propose an original model, inspired by the
Boguta-Bodmer models, which allows us to control the repulsion interaction at
high densities. For each version of the model we obtain a stability window as
predicted by the Bodmer-Witten conjecture and discuss its thermodynamic
consistency.
