Two measures theory approach to bags and confinement

We consider the question of bags and confinement in the framework of a theory which uses two volume elements -gd ⁴x and Φd ⁴x, where Φ is a metric independent density. For scale invariance a dilaton field Φ is considered. Using the first order formalism, curvature (ΦR and √-gR ²) terms, gauge field term (Φ -F _μν ^a F _αβ ^a g ^μα g ^νβ and √-g F _μν ^a F _αβ ^a g ^μα g ^νβ) and dilaton kinetic terms are introduced in a conformally invariant way. Exponential potentials for the dilaton break down (softly) the conformal invariance down to global scale invariance, which also suffers s.s.b. after integrating the equations of motion. The model has a well defined flat space limit. As a result of the s.s.b. of scale invariance phases with different vacuum energy density appear. Inside the bags the gauge dynamics is normal, that is non confining, while for the outside, the gauge field dynamics is confining.