Transplanckian axions!?

By M. Montero, A. Uranga, I. Valenzuela. 2015

211 citations recorded by the source corpus.

A bstractWe discuss quantum gravitational effects in Einstein theory coupled to periodic axion scalars to analyze the viability of several proposals to achieve superplanckian axion periods (aka decay constants) and their possible application to large field inflation models. The effects we study correspond to the nucleation of euclidean gravitational instantons charged under the axion, and our results are essentially compatible with (but independent of) the Weak Gravity Conjecture, as follows: single axion theories with superplanckian periods contain gravitational instantons inducing sizable higher harmonics in the axion potential, which spoil superplanckian inflaton field range. A similar result holds for multi-axion models with lattice alignment (like the Kim-Nilles-Peloso model). Finally, theories with N axions can still achieve a moderately superplanckian periodicity (by a N$$ \sqrt{N} $$ factor) with no higher harmonics in the axion potential. The Weak Gravity Conjecture fails to hold in this case due to the absence of some instantons, which are forbidden by a discrete ZN gauge symmetry. Finally we discuss the realization of these instantons as euclidean D-branes in string compactifications.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e1a0e50a8f30eaaec708656c8f48bda8cf88065f

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Citations in the corpus

Evidence for a sublattice weak gravity conjecture (2016, background): “From a phenomenological perspective, the WGC is especially interesting due to its ability to constrain models of large-field axion inflation [6–25].”
The Swampland: Introduction and Review (2019, background): “19 There have been many studies related to this idea [7, 8, 26, 86, 105,106,109,111,115–149], some of which we will discuss in more detail in section 4.”
The Weak Gravity Conjecture in three dimensions (2016, methodology): “In particular, it has been recently applied to large-field inflationary models and relaxions [2–22].”
Fencing in the swampland: quantum gravity constraints on large field inflation (2015, result): “The results of [18,19], which appeared while this paper was being finalized, contain a significant overlap with our results which, were presented at the MCTP Workshop “String/Mtheory Compactifications and Moduli Stabilization”.”
Early dark energy does not restore cosmological concordance (2020, background): “[59] M.”
Euclidean Wormholes, Baby Universes, and Their Impact on Particle Physics and Cosmology (2018, background): “The potentially strong constraints on large-field inflation arising from the weak gravity conjecture are being intensely studied, and are one of the main reasons for the current interest in wormhole physics [76,93,95].”
Recent Progress in the Physics of Axions and Axion-Like Particles (2020, unknown): “12) while giving ∆aL > MP [130–135].”
Planckian axions and the Weak Gravity Conjecture (2015, methodology): “The claim of [2] is that in theories with sufficiently large super-Planckian axion decay constants, gravitational instanton contributions to the axion potential lead to unsuppressed higher harmonic terms that preclude inflation.”
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].”