Abstract

Bubbles of nothing are a class of vacuum decay processes present in some theories with compactified extra dimensions. We investigate the existence and properties of bubbles of nothing in models where the scalar pseudomoduli controlling the size of the extra dimensions are stabilized at positive vacuum energy, which is a necessary feature of any realistic model. We map the construction of bubbles of nothing to a four-dimensional Coleman-De Luccia problem and establish necessary conditions on the asymptotic behavior of the scalar potential for the existence of suitable solutions. We perform detailed analyses in the context of five-dimensional theories with metastable dS4× S1 vacua, using analytic approximations and numerical methods to calculate the decay rate. We find that bubbles of nothing sometimes exist in potentials with no ordinary Coleman-De Luccia decay process, and that in the examples we study, when both processes exist, the bubble of nothing decay rate is typically faster. Our methods can be generalized to other stabilizing potentials and internal manifolds.

Highlights

  • Our Universe is entering a phase of dark energy domination

  • We find that bubbles of nothing sometimes exist in potentials with no ordinary Coleman-De Luccia decay process, and that in the examples we study, when both processes exist, the bubble of nothing decay rate is typically faster

  • When u0 1 we find that the bubble of nothing (BON) and Coleman-De Luccia (CDL)/HM branches of solutions eventually merge together, with ∆S approaching the action of the CDL solution, ∆S ≈ ∆SCDL

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Summary

Introduction

Our Universe is entering a phase of dark energy domination. To date, cosmological observations are consistent with an epoch of late-time acceleration driven by a small and positive cosmological constant [1,2,3]. The scalar field plays the role of the radial modulus setting the size of the S1, and Witten’s solution is recovered in the case of a vanishing scalar potential This fourdimensional description, makes it natural to consider generalizations of the BON in the presence of a potential for the moduli, as first suggested in [32]. Our goals are to describe, from the four-dimensional perspective, existence criteria for BON solutions in theories with stabilized moduli; to develop analytic approximations for the BON action in the presence of a scalar potential; to compare the corresponding decay rate to those of the ordinary CDL and HM channels; and to study numerically those examples that are analytically intractable. A series of appendices collect various additional results of a more detailed or tangential nature and are referred to throughout the text

Vacuum decay in the presence of gravity
Bubble of nothing as a Coleman-De Luccia problem
Sources of moduli potentials
Classical vs effective potentials
Bounce of nothing
Bubble existence conditions
A toy model
A bounce of nothing
R52 2 ρ2
De Sitter decay rate
Application to more generic potentials
Other exotic bounces
Numerical construction of bounce solutions
Exponentially falling potentials
Parameter space of BON solutions
Field profiles
Instanton action
Exponentially growing potential: five-dimensional CC
Conclusions
A Solutions to equations of motion
Witten bubble of nothing
Constant potential
Small ξ limits
Piecewise linear model
B Analytic continuation
C Specific potential
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