Euclidean Wormholes, Baby Universes, and Their Impact on Particle Physics and Cosmology

Hebecker, Arthur; Mikhail, Thomas; Soler, Pablo

doi:10.3389/fspas.2018.00035

Cited by 115 publications

(126 citation statements)

References 239 publications

(435 reference statements)

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“…Some early work on such solutions in string theory is [], and see [] for recent work. There is a detailed recent review on these objects and their relation to the Weak Gravity Conjecture, so here we can be brief. These are solutions to the Euclidean action with metric of the form

d s^{2} = {(1 + \frac{C}{r^{4}})}^{- 1} d r^{2} + r^{2} d {normalΩ}_{3}^{2} .

Here C is some constant which is calculable given a particular action.…”

Section: Charting the Swamplandmentioning

confidence: 99%

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The Swampland: Introduction and Review

Palti

2019

Fortschritte der Physik

902

1,097

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The Swampland program aims to distinguish effective theories which can be completed into quantum gravity in the ultraviolet from those which cannot. This article forms an introduction to the field, assuming only a knowledge of quantum field theory and general relativity. It also forms a comprehensive review, covering the range of ideas that are part of the field, from the Weak Gravity Conjecture, through compactifications of String Theory, to the de Sitter conjecture.

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d s^{2} = {(1 + \frac{C}{r^{4}})}^{- 1} d r^{2} + r^{2} d {normalΩ}_{3}^{2} .

Here C is some constant which is calculable given a particular action.…”

Section: Charting the Swamplandmentioning

confidence: 99%

“…While black holes are the natural objects to utilize for global U (1) symmetries, for shift symmetries the appropriate objects are more closely related to Euclidean wormholes, see [] for a recent review.…”

mentioning

confidence: 99%

The Swampland: Introduction and Review

Palti

2019

Fortschritte der Physik

902

1,097

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“…However, the interpretation and consistency of these Euclidean wormhole effects is a subject of debate (see Ref. [13] for a recent review).…”

Section: Contentsmentioning

confidence: 99%

Approximate symmetries and gravity

Fichet

Saraswat

2020

J. High Energ. Phys.

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There are strong reasons to believe that global symmetries of quantum theories cannot be exact in the presence of gravity. While this has been argued at the qualitative level, establishing a quantitative statement is more challenging. In this work we take new steps towards quantifying symmetry violation in EFTs with gravity. First, we evaluate global charge violation by microscopic black holes present in a thermal system, which represents an irreducible, universal effect at finite temperature. Second, based on general QFT considerations, we propose that local symmetry-violating processes should be faster than black hole-induced processes at any sub-Planckian temperature.Such a proposal can be seen as part of the "swampland" program to constrain EFTs emerging from quantum gravity. Considering an EFT perspective, we formulate a conjecture which requires the existence of operators violating global symmetry and places quantitative bounds on them. We study the interplay of our conjecture with emergent symmetries in QFT. In models where gauged U (1)'s enforce accidental symmetries, we find that constraints from the Weak Gravity Conjecture can ensure that our conjecture is satisfied. We also study the consistency of the conjecture with QFT models of emergent symmetries such as extradimensional localization, the Froggatt-Nielsen mechanism, and the clockwork mechanism.

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“…1 However, a priori the WGC does not make a claim about the overall size of the axion potential. Thus, the potential could be small because e −S comes with a small prefactor [10][11][12][13]. In the following we want to take the bound on S seriously and focus on the prefactor.…”

Section: Fermions and Axion Potentialsmentioning

confidence: 99%

Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials

Hebecker

Henkenjohann

2019

J. High Energ. Phys.

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We investigate the role of gauge and gravitational instantons in the context of the Swampland program. Our focus is on the global symmetry breaking they induce, especially in the presence of fermions. We first recall and make more precise the description of the dilute instanton gas through a 3-form gauge theory. In this language, the familiar suppression of instanton effects by light fermions can be understood as the decoupling of the 3-form. Even if all fermions remain massive, such decoupling may occur on the basis of an explicitly unbroken but anomalous global symmetry in the fermionic sector. This should be forbidden by quantum gravity, which leads us to conjecture a related, cutoff-dependent lower bound on the induced axion potential. Finally, we note that the gravitational counterpart of the above are K3 instantons. These are small fluctuations of Euclidean spacetime with K3 topology, which induce fermionic operators analogous to the 't Hooft vertex in gauge theories. Although Planck-suppressed, they may be phenomenologically relevant if accompanied by other higherdimension fermion operators or if the K3 carries appropriate gauge fluxes.

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Euclidean Wormholes, Baby Universes, and Their Impact on Particle Physics and Cosmology

Cited by 115 publications

References 239 publications

The Swampland: Introduction and Review

The Swampland: Introduction and Review

Approximate symmetries and gravity

Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials

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