Domain Walls, near-BPS Bubbles and Probabilities in the Landscape

Abstract

We develop a theory of static Bogomol'nyi-Prasad-Sommerfield (BPS) domain walls in stringy landscape and present a large family of BPS walls interpolating between different supersymmetric vacua. Examples include Kachru, Kallosh, Linde, Trivedi models, STU models, type IIB multiple flux vacua, and models with several Minkowski and anti-de Sitter vacua. After the uplifting, some of the vacua become de Sitter (dS), whereas some others remain anti-de Sitter. The near-BPS walls separating these vacua may be seen as bubble walls in the theory of vacuum decay. As an outcome of our investigation of the BPS walls, we found that the decay rate of dS vacua to a collapsing space with a negative vacuum energy can be quite large. The parts of space that experience a decay to a collapsing space, or to a Minkowski vacuum, never return back to dS space. The channels of irreversible vacuum decay serve as sinks for the probability flow. The existence of such sinks is a distinguishing feature of the landscape. We show that it strongly affects the probability distributions in string cosmology.

Field dynamics and tunneling in a flux landscape

“…This is an important property to establish, and has been a topic of some controversy in the past [17,18]. In addition, our picture of transitions in the flux landscape illustrates a number of features not present in the flux lattice of the BoussoPolchinski landscape [19], and we are able to clarify the connection between near-BPS domain walls [20] and Dand NS-brane bubbles. These results complement the recent analysis of Ref.…”

“…35 once the vacuum energies are known. This can be compared with the analysis of [20,21], where such thin-wall transitions were considered. In reality, there will most likely be a spectrum between thin-and thickwall solutions, determined by the hierarchy of scales between the barrier height and the vacuum energy splitting.…”

“…Following [20], if the potential energy of one of the minima were lifted by a small amount (using ingredients such as branes to do so in a controlled way), the minimum would no longer be totally stable. Provided that this uplift is small, the thin-wall analysis could be applied and the tension of the bubble computed using Eq.…”

Life at the interface of particle physics and string theory

“…Up-tunneling from these vacua to dS space is impossible, and therefore they are called terminal vacua. They are "sinks in the probability flow" (Ceresole et al, 2006;Linde, 2007). According to Bousso (2012) and Susskind (2012a) their existence in the landscape may be essential for understanding the arrow of time and for avoiding the Boltzmann Brain problem (see below).…”

Generalized surface tension bounds in vacuum decay

“…In its stead there is a static planar domain wall [3,4]. Such walls have been constructed as BPS solutions in supergravity theories [5][6][7][8][9], but they can also arise as solutions that only possess what has been termed "fake supersymmetry" [10][11][12]. We will describe how this happens in our approach.…”