Catalytic creation of baby bubble universe with small positive cosmological constant

Abstract

We investigate the decay of metastable de Sitter, Minkowski and anti-de Sitter vacua catalyzed by a black hole and a cloud of strings. We apply the method to the creation of the four dimensional bubble universe in the five dimensional anti-de Sitter spacetime recently proposed by Banerjee, Danielsson, Dibitetto, Giri and Schillo [1]. We study the bounce action for the creation and find that the bubble with very small cosmological constant, of order Λ (4) /M 2 4 ∼ 10 −120 , is favored by the catalysis by assuming appropriate mass scales of the black hole and the cloud of strings to reproduce the present energy densities of matter and radiation in the bubble universe.

Dark bubbles: decorating the wall

“…Such modes can appear, for example, when there is a black hole in the bulk spacetime. 9 In our case, with the source on the shell, we no longer have pure AdS spacetime. Let us use this fact to postulate that such non-propagating modes do exist in our case, and let us study the gravitational propagator between two bulk points across the shell for these modes.…”

Bubble needs strings

“…The role of the stretched strings, and the nature of four dimensional gravity, was subsequently elaborated in [2,3]. By computing the bounce action of the shell in the presence of a cloud of strings and a Schwarzschild mass in five dimensions, [8] showed that the preferred nucleation channel is a bubble with slightly sub-critical tension, giving a phenomenologically realistic four dimensional cosmological constant. Recently, a top down construction of a (p + 1) dimensional dS shellworld, via the nucleation of a p dimensional bubble in an AdS p+2 × S q bulk, was done for p = 1, 5 in ten dimensional non-supersymmetric string theory by [9].…”

Gravitational waves in dark bubble cosmology

“…Its advantage is twofold: it evades the swampland constraints of constructing 'fundamental' dS vacua based on pure compactifications of string theory [11] and, at the same time, it provides a concrete realisation of a braneworld in string theory with an inside-outside construction (in contrast to the inside-inside structure of RS or KR models). In [12][13][14][15] the physics of nucelation in AdS 5 was further studied, while [16] discusses a concrete realization of the dark bubble throguh a resolved Calabi-Yau conifold.…”