Ground state energy and topological mass in spacetimes with nontrivial topology

Abstract: In the present paper, we investigate the ground state energy of a massless scalar field and generation of topological mass by considering a quasi-periodically identified Minkowski spacetime and the `half-Einstein Universe', that is, an Einstein Universe where the massless scalar field propagates under Dirichlet boundary condition. The analysis is performed considering one and two-loop corrections to the effective potential in both cases. Our results are compared with previous results found in literature.