William Cottrell

Fencing in the swampland: quantum gravity constraints on large field inflation

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.

On axionic field ranges, loopholes and the weak gravity conjecture

A bstractIn this short note we clarify some aspects of the impact that the Weak Gravity Conjecture has on models of (generalized) natural inflation. We address in particular certain technical and conceptual concerns recently raised regarding the stringent constraints and conclusions found in our previous work [1]. We also point out the difficulties faced by attempts to evade these constraints. These new considerations improve the understanding of the quantum gravity constraints we found and further support the conclusion that it remains challenging for axions to drive natural inflation.

Gravity dual of dynamically broken supersymmetry

A bstractWe study a renormalization group flow of ABJM theory embedded into the warped A8 geometry and explore the dependence of the vacuum structure on the parameters of the theory. This model has a product group gauge structure U(N)k × U(N + l)−k and comes equipped with discrete parameters N, l, and k, a continuous parameter b∞ related to the ratio of the Yang-Mills coupling for the two gauge groups, and one dimensionful parameter

Tunneling in Axion Monodromy

g_{YM}^2

Solitons on intersecting 3-branes

setting the overall scale. A supersymmetric supergravity solution exists when Q = N − l(l − k)/2k − k/24 is positive and is interpretable as a RG flow from a Yang-Mills like UV fixed point to a superconformal IR fixed point with free energy of order Q3/2. The fate of the theory when Q is taken to be negative is less clear. We explore the structure of the possible gravity solution for small negative Q by considering the linearized gravitational back reaction from adding a small number of anti-branes on the Q = 0 background. Following the work of Bena, Graña, and Halmagyi, we find that a sensible solution satisfying appropriate boundary conditions does not appear to exist. This leaves the status of the RG flow for the Q < 0 theories a mystery. We offer the following speculative resolution to the puzzle: the −k/24 unit of charge induced by the curvature correction to supergravity should be considered an allowed physical object, and one should be adding an anti brane not to the Q = 0 background but rather the Q = −k/24 background. Such a solution has a repulson singularity, and gives rise to a picture of the vacuum configuration where a cluster of anti-branes are floating around the repulson singularity, but are stabilized from being pushed off to infinity by other fluxes. Such a state is non-supersymmetric and appears to describe a vacuum with dynamical breaking of supersymmetry. Based on these considerations, we construct a phase diagram for this theory exhibiting various interesting regions.

Resolved gravity duals of \( \mathcal{N}=4 \) quiver field theories in 2 + 1 dimensions

A bstractThe Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman’s original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.

Dynamics of

A bstractWe consider a system consisting of a pair of D3 branes intersecting each other along a line such that half of the 16 supersymmetries are preserved. We then study the existence of magnetic monopole solutions corresponding to a D1-brane suspended between these D3 branes. We consider this problem in the zero slope limit where the tilt of the D3-branes is encoded in the uniform gradient of the adjoint scalar field. Such a system is closely related to the non-abelian flux background considered originally by van Baal. We provide three arguments supporting the existence of a single magnetic monopole solution. We also comment on the relation between our construction and a recent work by Mintun, Polchinski, and Sun.

\mathcal{N}

A bstractWe generalize the construction by Aharony, Hashimoto, Hirano, and Ouyang of N=4

Solitons on intersecting 3-branes II: a holographic perspective

\mathcal{N}=4