De Sitter Quantum Breaking, Swampland Conjectures and Thermal Strings

TL;DR

This paper explores how quantum breaking and swampland conjectures impose similar constraints on de Sitter space, linking quantum effects, string theory, and the limits of eternal inflation.

Contribution

It demonstrates that quantum breaking and swampland conjectures yield equivalent de Sitter constraints and connects quantum effects in string theory to cosmological bounds.

Findings

Quantum breaking leads to de Sitter swampland constraints.

Imposing quantum breaking censorship recovers the no eternal inflation bound.

Stronger bounds emerge under assumptions about high-temperature string regimes.

Abstract

We argue that under certain assumptions the quantum break time approach and the trans-Planckian censorship conjecture both lead to de Sitter swampland constraints of the same functional form. It is a well known fact that the quantum energy-momentum tensor in the Bunch-Davies vacuum computed in the static patch of dS breaks some of the isometries. Proposing that this is a manifestation of quantum breaking of dS, we analyze some of its consequences. In particular, this leads to a thermal matter component that can be generalized to string theory in an obvious way. Imposing a censorship of quantum breaking, we recover the no eternal inflation bound in the low temperature regime, while the stronger bound from the dS swampland conjecture follows under a few reasonable assumptions about the still mysterious, presumably topological, high-temperature regime of string theory.