Fencing in the swampland: quantum gravity constraints on large field inflation
By Jon Brown, William Cottrell, Gary Shiu, Pablo Soler. 2015
233 citations recorded by the source corpus.
A bstractIn this note we show that models of natural inflation based on closed string axions are incompatible with the weak gravity conjecture (WGC). Specifically, we use T- duality in order to map the bounds on the charge-to-mass ratio of particles imposed by the WGC, to constraints on the ratio between instanton actions and axion decay constants. We use this connection to prove that if the WGC holds, even when multiple axions are present and mix with each other, one cannot have large axion decay constants while remaining in a regime of perturbative control. We also discuss the extension of the WGC to discrete symmetries and its possible impact on models with axion monodromy, and the distinction between the strong and mild versions of the WGC. We argue that, if the strong version is violated, the constraints on large field inflation can be evaded while still satisfying the mild one. Finally, we offer some speculations regarding the import of these results to the general theory of inflation.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/0d286310d18efd62d02c901b5d2880a6071d144e
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Citations in the corpus
- The Weak Gravity Conjecture in three dimensions (2016, background): “Both the WGC and its generalizations to several U(1)’s (such as those discussed in [6, 9, 13, 38]) or higher p-form gauge fields have always been validated in every string theory construction where it has been checked.”
- Planckian axions and the Weak Gravity Conjecture (2015, methodology): “Finding an example of an explicit flux compactification in which the axion fundamental domain has a superPlanckian diameter D — which according to [3] is incompatible with the WGC — is not difficult [9].”
- Weak gravity strongly constrains large-field axion inflation (2015, methodology): “On the other hand, several authors have argued for precisely such statements regarding large-field inflation models [66–68], including recently in the context of the Weak Gravity Conjecture [51].”
- Backreacted axion field ranges in string theory (2016, unknown): “Using the WGC applied to axions implies a relation between the magnitude of the instanton, which is the modulus vev u, and the axion decay constant fa [2, 5] SInstfa = ufa ≤Mp .”
- Sharpening the weak gravity conjecture with dimensional reduction (2015, background): “In the context of axion inflation, wormhole solutions have previously been studied by [8, 10] and criticized by [9, 12].”
- A Tower Weak Gravity Conjecture from Infrared Consistency (2018, methodology): “The requirement for an ultraviolet-completable theory to be well-behaved upon compactification has been used as a guiding principle for distinguishing the landscape from the swampland [5, 35, 43].”
- The Swampland: Introduction and Review (2019, methodology): “This way the Weak Gravity Conjecture is satisfied, but the axion potential is hardly modified [109,110].”
- Euclidean Wormholes, Baby Universes, and Their Impact on Particle Physics and Cosmology (2018, background): “Setups in which the instanton that satisfies the WGC is not the one of lowest charge have been proposed as a loophole to this strong constraint [75,77,80] and are being actively investigated [79].”
- Relaxion monodromy and the Weak Gravity Conjecture (2015, methodology): “p is precisely the inverse of the parameter A in [53].”
- Recent Progress in the Physics of Axions and Axion-Like Particles (2020, methodology): “12) while giving ∆aL > MP [130–135].”