Fubini instantons in Dilatonic Einstein-Gauss-Bonnet theory of gravitation

TL;DR

This paper explores Fubini instantons within Dilatonic Einstein-Gauss-Bonnet theory, revealing how higher-curvature terms modify vacuum states and influence tunneling probabilities in various cosmological backgrounds.

Contribution

It introduces new instanton solutions affected by non-minimal couplings, showing their impact on vacuum decay and tunneling probabilities in modified gravity theories.

Findings

Vacuum states are altered by higher-curvature terms.

New tunneling solutions are found in AdS and dS backgrounds.

Decay probabilities can be significantly increased under certain parameters.

Abstract

We investigate various types of Fubini instantons in Dilatonic Einstein-Gauss-Bonnet theory of gravitation, which describe the decay of the vacuum state at a hilltop potential through the tunneling without a barrier. It is shown that the vacuum states are modified by the non-minimally coupled higher-curvature term. Accordingly, we present the new type of solutions describing the tunneling from new vacuum states in anti-de Sitter and de Sitter backgrounds. The decay probabilities of vacuum states are also influenced. Consequently, we show that the semiclassical exponents can be decreased for specific parameter ranges, which make the tunneling probabilities enhanced.