Quantum Breaking Bound on de Sitter and Swampland

Abstract

Quantum consistency suggests that any de Sitter patch that lasts a number of Hubble times that exceeds its Gibbons‐Hawking entropy divided by the number of light particle species suffers an effect of quantum breaking. Inclusion of other interactions makes the quantum break‐time shorter. The requirement that this must not happen puts severe constraints on scalar potentials, essentially suppressing the self‐reproduction regimes. In particular, it eliminates both local and global minima with positive energy densities and imposes a general upper bound on the number of e‐foldings in any given Hubble patch. Consequently, maxima and other tachyonic directions must be curved stronger than the corresponding Hubble parameter. We show that the key relations of the recently‐proposed de Sitter swampland conjecture follow from the de Sitter quantum breaking bound. We give a general derivation and also illustrate this on a concrete example of D‐brane inflation. We can say that string theory as a consistent theory of quantum gravity nullifies a positive vacuum energy in self‐defense against quantum breaking.

The Swampland: Introduction and Review

“…This is a type of discharge of the cosmological constant into matter and radiation. In [] a different argument for an instability of de Sitter space was presented. The idea is to consider de Sitter space as a coherent state of gravitons on top of a Minkowski background.…”

Further Refining the de Sitter Swampland Conjecture

“…This refined de Sitter conjecture has been tested with various phenomenological models, [14][15][16][17][18][19] and has been discussed in relation to stringy constructions [20][21][22][23][24][25][26][27] or in a more general swampland context. [28][29][30][31] In the present paper, we propose an alternative refined de Sitter conjecture.…”

Trans-Planckian Censorship and single-field inflaton potential

“…The lines are horizontal since α s and N total are in one-to-one correspondence as in eq. (29). The relation is insensitive to the inflation energy scale or N CMB because the running is essentially contributed by the cubic term around the inflection point, i.e.…”