Vacuum fluctuations and the renormalized stress-energy tensor on a cone with arbitrary boundary conditions
arXiv:2509.20231 · doi:10.1103/6fjz-y6y6
The paper studies how quantum vacuum fluctuations and the stress‑energy tensor of a massive scalar field behave in a conical spacetime when various boundary conditions are imposed at the apex, and shows that a localized mode can serve as an extended particle detector that alters the local vacuum structure.
Abstract
We analyze the vacuum fluctuations and the stress-energy tensor of a scalar field of mass in a conical spacetime, where the topological singularity at the apex requires boundary conditions for the field equation. The necessity of boundary conditions was established by Kay and Studer in the early 1990s, while for stability is achieved only under Dirichlet boundary conditions, and for the field is stable and a localized mode emerges. This mode admits a natural interpretation as a covariant model of an extended particle detector, which allows us to investigate whahow such detectors modify the local vacuum structure. In this framework, the renormalized stress-energy tensor offers a natural way to quantify the influence of the detector on the surrounding spacetime.