Description
Scalar fields coupled to gravity can display spectacular dynamics in the aftermath of inflation. In cosmological scenarios featuring a brief period of kination, the rapid evolution of spacetime curvature can destabilize otherwise symmetric vacua, triggering curvature-driven phase transitions through tachyonic instabilities. These purely gravitational effects can explosively amplify field fluctuations, seed short-lived networks of topological defects, and efficiently convert vacuum energy into radiation—opening a new and economical route to reheating and to the production of stochastic gravitational-wave backgrounds. In this talk, I will present the basic mechanism and explore its broader cosmological implications, with the Standard Model Higgs field as a particularly compelling realization. The resulting interplay between spacetime curvature, electroweak vacuum stability, and non-perturbative field dynamics offers a minimal yet predictive framework that links fundamental particle physics to potentially observable gravitational-wave signals in upcoming experiments.
