Vacuum polarization of a massless scalar field in the background of a global monopole with finite core

In this paper, we analyse the vacuum polarization effects of a massless scalar field in the background of a global monopole considering its inner structure. Specifically we investigate the effect of its structure on the vacuum expectation value of the square of the field operator, , admitting a non-minimal coupling between the field with the geometry: . Also, we calculate the corrections to the vacuum expectation value of the energy–momentum tensor, , due to the inner structure of the monopole. In order to develop these analyses, we calculate the Euclidean Green function associated with the system for points in the region outside the core. As we shall see, for a specific value of the coupling parameter ξ, the corrections caused by the inner structure of the monopole can provide relevant contributions to these vacuum polarizations.