Phase-resolved scalar distance bounds are derived for ekpyrotic, bouncing, and cyclic cosmologies, yielding a master condition that lower-bounds ε_ek from remaining distance after conversion and bounce.
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The Swampland: Introduction and Review
Canonical reference. 100% of citing Pith papers cite this work as background.
abstract
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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The Schwinger integral over light towers captures precisely the instantons with actions in the window (Λ_sp/M_light)^{-1} ≤ S_inst ≤ Λ_sp/M_light, as verified in eight- and seven-dimensional toroidal compactifications.
In codimension-one warped compactifications with exponential potentials, the KK mass decay rate λ_KK is reduced by warping but still satisfies the Sharpened Distance Conjecture precisely when the higher-dimensional potential obeys the Strong de Sitter condition.
Generic 2D Horndeski theories arise from dimensional reduction of d≥4 gravities, yielding a Birkhoff theorem for quasi-topological gravities where static spherically symmetric solutions satisfy g_tt g_rr = -1 and are determined algebraically.
RG-improved black hole spacetimes with scale-dependent gravitational coupling are derived as vacuum solutions to 2D Horndeski master field equations, embedding prior works and exposing implementation discrepancies.
Defines IR-finite amplitudes M_E that preserve analyticity and unitarity to derive positivity bounds on EFTs including electromagnetism and gravity in D=4.
Explicit scale-separated dS5 maximum in M-theory on a 6D Riemann-flat manifold with vacuum energy 10^{-8} in Planck units, obtained via Casimir energies and fluxes.
Causal sets can approximate black hole horizons via discrete timelike curves and ladders tracing null geodesics, with a discrete expansion changing sign across the horizon in a 1+1D toy model.
Optimal transport yields a generalized Wasserstein distance on field space, obtained from a WKB expansion of a Schrödinger equation and extended to dynamical gravity via the Wheeler-DeWitt equation in the ADM formalism.
Proposes a refinement of the Swampland Cobordism Conjecture for Ω1(BG) with duality bundle G, where diverging commutator width of G requires infinitely many duality defects to realize monodromies via gravitational solitons.
Six-dimensional primordial black holes with memory burden effects can survive as light dark matter in a two-extra-dimension model at the 10 TeV scale, producing high-multiplicity thermal events at future colliders.
Refines charge quantization via homotopy type A whose homotopy groups classify brane charges and homology groups classify higher-form symmetries, deriving swampland-like constraints that rule out noncompact gauge groups and non-nilpotent Lie algebras for field strengths.
Five-dimensional rotating primordial black holes with initial masses above 10^10 grams survive to today and can account for all dark matter due to suppressed Hawking radiation and memory burden effects in the micron-scale dark dimension.
In asymptotically safe gravity, dimension-five couplings of ultralight scalar dark matter to gauge field strengths vanish and are not generated perturbatively.
Morse-Bott inequalities yield homology bounds and topology-change counts for generic cobordisms to nothing in string theory compactifications.
Derives WGC bound on probe charge-to-mass ratio from positivity of anomalous dimensions in dual CFT for charged particles in higher-derivative AdS black holes, with bound increasing with couplings and ISCOs existing up to the bound.
A sampling-based bootstrap for graviton poles in EFTs yields non-projective bounds that fix the EFT cutoff scale relative to the Planck mass, with M/M_P ≲ 7.8 in D=5.
An analytic bound on axion parameters in thawing quintessence is derived independently of initial conditions and used with cosmological observations plus quantum gravity constraints to exclude large regions of axion dark energy parameter space.
The paper verifies the bound fS/|n| ≤ (π/(2 κ_d)) sqrt((d-1)/(d-2)) for axion instantons and sharpens it to fS/|n| ≤ (1/κ_4) sqrt(7/2) for supersymmetric 4d instantons using three approaches in the string landscape.
Upper bounds are placed on the order of enhanced discrete gauge symmetries in supersymmetric supergravity theories with 8 or more supercharges, with some bounds saturated by string theory examples.
Hořava-Witten theory offers a potential string embedding of the dark dimension by localizing the Standard Model on the 11th interval, with symmetric tadpole cancellation and an infinite-distance limit helping derive the scalar potential and couplings from Schwinger integrals.
In G-theory motivated Type IIB compactifications with varying fields, End of the World branes trivialize a cohomology class and additional non-perturbative objects are required to cancel the bordism group while retaining the class as a subgroup.
The Species Scale implies Laplace eigenvalue equations for BPS-protected Wilson coefficients and produces a one-loop moduli potential with minima at desert points that may stabilize Kähler moduli in 4d Type IIB orientifolds.
Numerical study of interacting Barrow holographic dark energy in non-flat universes with radiation, showing EoS transitions and higher fitted H0 values that may address Hubble tension.
citing papers explorer
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Phase-resolved field-space distance bounds in ekpyrotic, bouncing and cyclic cosmologies
Phase-resolved scalar distance bounds are derived for ekpyrotic, bouncing, and cyclic cosmologies, yielding a master condition that lower-bounds ε_ek from remaining distance after conversion and bounce.
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Taxonomy of Instanton Corrections in Infinite Distance Limits
The Schwinger integral over light towers captures precisely the instantons with actions in the window (Λ_sp/M_light)^{-1} ≤ S_inst ≤ Λ_sp/M_light, as verified in eight- and seven-dimensional toroidal compactifications.
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Alice in Warpland: KK modes, Warped Compactifications and the Swampland
In codimension-one warped compactifications with exponential potentials, the KK mass decay rate λ_KK is reduced by warping but still satisfies the Sharpened Distance Conjecture precisely when the higher-dimensional potential obeys the Strong de Sitter condition.
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All $2D$ generalised dilaton theories from $d\geq 4$ gravities
Generic 2D Horndeski theories arise from dimensional reduction of d≥4 gravities, yielding a Birkhoff theorem for quasi-topological gravities where static spherically symmetric solutions satisfy g_tt g_rr = -1 and are determined algebraically.
-
Effective geometrodynamics for renormalization-group improved black-hole spacetimes in spherical symmetry
RG-improved black hole spacetimes with scale-dependent gravitational coupling are derived as vacuum solutions to 2D Horndeski master field equations, embedding prior works and exposing implementation discrepancies.
-
Positivity with Long-Range Interactions
Defines IR-finite amplitudes M_E that preserve analyticity and unitarity to derive positivity bounds on EFTs including electromagnetism and gravity in D=4.
-
An M-theory dS maximum from Casimir energies on Riemann-flat manifolds
Explicit scale-separated dS5 maximum in M-theory on a 6D Riemann-flat manifold with vacuum energy 10^{-8} in Planck units, obtained via Casimir energies and fluxes.
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Towards black-hole horizons and geodesic focusing in causal sets
Causal sets can approximate black hole horizons via discrete timelike curves and ladders tracing null geodesics, with a discrete expansion changing sign across the horizon in a 1+1D toy model.
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Optimal paths across potentials on scalar field space
Optimal transport yields a generalized Wasserstein distance on field space, obtained from a WKB expansion of a Schrödinger equation and extended to dynamical gravity via the Wheeler-DeWitt equation in the ADM formalism.
-
Bordisms between 9d type IIB supergravities and commutator widths of duality groups
Proposes a refinement of the Swampland Cobordism Conjecture for Ω1(BG) with duality bundle G, where diverging commutator width of G requires infinitely many duality defects to realize monodromies via gravitational solitons.
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Micron-sized Extra Dimensions and Primordial Black Holes: Charged, Rotating, and Memory Burdened
Six-dimensional primordial black holes with memory burden effects can survive as light dark matter in a two-extra-dimension model at the 10 TeV scale, producing high-multiplicity thermal events at future colliders.
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Generalised Symmetries and Swampland-Type Constraints from Charge Quantisation via Rational Homotopy Theory
Refines charge quantization via homotopy type A whose homotopy groups classify brane charges and homology groups classify higher-form symmetries, deriving swampland-like constraints that rule out noncompact gauge groups and non-nilpotent Lie algebras for field strengths.
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5D Rotating Black Holes as dark matter in Dark Dimension Scenario: Hawking Radiation versus the Memory Burden Effect
Five-dimensional rotating primordial black holes with initial masses above 10^10 grams survive to today and can account for all dark matter due to suppressed Hawking radiation and memory burden effects in the micron-scale dark dimension.
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Towards theory constraints on ultralight dark matter from quantum gravity
In asymptotically safe gravity, dimension-five couplings of ultralight scalar dark matter to gauge field strengths vanish and are not generated perturbatively.
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Morse-Bott inequalities, Topology Change and Cobordisms to Nothing
Morse-Bott inequalities yield homology bounds and topology-change counts for generic cobordisms to nothing in string theory compactifications.
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ISCOs and the weak gravity conjecture bound in higher derivative theories of gravity
Derives WGC bound on probe charge-to-mass ratio from positivity of anomalous dimensions in dual CFT for charged particles in higher-derivative AdS black holes, with bound increasing with couplings and ISCOs existing up to the bound.
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Sampling the Graviton Pole and Deprojecting the Swampland
A sampling-based bootstrap for graviton poles in EFTs yields non-projective bounds that fix the EFT cutoff scale relative to the Planck mass, with M/M_P ≲ 7.8 in D=5.
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Bounding axion dark energy
An analytic bound on axion parameters in thawing quintessence is derived independently of initial conditions and used with cosmological observations plus quantum gravity constraints to exclude large regions of axion dark energy parameter space.
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Sharpening the Supersymmetric Axion Weak Gravity Conjecture
The paper verifies the bound fS/|n| ≤ (π/(2 κ_d)) sqrt((d-1)/(d-2)) for axion instantons and sharpens it to fS/|n| ≤ (1/κ_4) sqrt(7/2) for supersymmetric 4d instantons using three approaches in the string landscape.
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Bounds on Discrete Gauge Symmetries in Supergravity
Upper bounds are placed on the order of enhanced discrete gauge symmetries in supersymmetric supergravity theories with 8 or more supercharges, with some bounds saturated by string theory examples.
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Towards the Realization of the Dark Dimension Scenario in Ho\v{r}ava-Witten Theory
Hořava-Witten theory offers a potential string embedding of the dark dimension by localizing the Standard Model on the 11th interval, with symmetric tadpole cancellation and an infinite-distance limit helping derive the scalar potential and couplings from Schwinger integrals.
-
Double fibration in G-theory and the cobordism conjecture
In G-theory motivated Type IIB compactifications with varying fields, End of the World branes trivialize a cohomology class and additional non-perturbative objects are required to cancel the bordism group while retaining the class as a subgroup.
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Some Properties and Uses of the Species Scale
The Species Scale implies Laplace eigenvalue equations for BPS-protected Wilson coefficients and produces a one-loop moduli potential with minima at desert points that may stabilize Kähler moduli in 4d Type IIB orientifolds.
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Barrow holographic dark energy interacting model in the presence of radiation and matter
Numerical study of interacting Barrow holographic dark energy in non-flat universes with radiation, showing EoS transitions and higher fitted H0 values that may address Hubble tension.
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Assisted Fibre Inflation in Perturbative LVS
Multi-field fibre inflation in perturbative LVS uses collective dynamics of several moduli to achieve viable cosmology with sub-Planckian individual field ranges given by total range divided by sqrt(n).
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The weak gravity conjecture in perturbative strings
A summary of a proposed proof that the Weak Gravity Conjecture follows from the structure of perturbative bosonic string theory.
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What to do with a Ricci-flat Calabi--Yau metric?
A roadmap paper describing potential applications of numerical Ricci-flat Calabi-Yau metrics to heterotic string phenomenology and mathematical questions in special geometry.
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Dark energy from string theory: an introductory review
String theory imposes constraints on dark energy but permits various construction attempts for de Sitter vacua and single-field exponential quintessence models despite obstructions.
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On Legacy of Starobinsky Inflation
A memorial review of the Starobinsky inflation model that proposes a deformation for primordial black hole production and discusses superstring quantum corrections plus universal reheating.
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ICTP Lectures on (Non-)Invertible Generalized Symmetries
Lecture notes explain non-invertible generalized symmetries in QFTs as topological defects arising from stacking with TQFTs and gauging diagonal symmetries, plus their action on charges and the SymTFT framework.
- Fifth-Force Constraints from UV-Complete Scalar-Tensor Gravity