Abstract The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good
description of a wide range of astrophysical and cosmological data. However, there are a …

A brief review is given of scalar field theories with second-derivative Lagrangians yielding
second-order field equations. Some of these theories permit solutions that violate the null …

We investigate the evolution of gravitational waves through discontinuous evolution
(transition) of the Hubble expansion rate H (z) at a sudden cosmological singularity, which …

The null energy condition (NEC) can be violated in a consistent way in models with
unconventional kinetic terms, notably, in Galileon theories and their generalizations. We …

We investigate first-order vacuum phase transitions in the presence of a non-minimally
coupled scalar field starting with the coupling effect on the initial dynamics of phase …

We study the possible types of nucleation of vacuum bubbles. We classify vacuum bubbles
in a de Sitter background and present some numerical solutions. The thin-wall …

We numerically study the dynamics of false vacuum bubbles which are inside an almost flat
background; we assumed spherical symmetry and the size of the bubble is smaller than the …

This paper suggests a model for a bubble universe using buildable false vacuum bubbles.
We study the causal structures of collapsing false vacuum bubbles using double-null …

We investigate oscillating instanton solutions of a self-gravitating scalar field between
degenerate vacua. We show that there exist O (4)-symmetric oscillating solutions in a de …

We study the effect of the Gauss–Bonnet term on vacuum decay process in the Coleman–De
Luccia formalism. The Gauss–Bonnet term has an exponential coupling with the real scalar …