Bifid Throats for Axion Monodromy Inflation

TL;DR

This work constructs an explicit local geometry realizing a bifid throat suitable for axion monodromy inflation, using a deformed Z3×Z2 orbifold of the conifold to produce three KS-like throats connected through a shared 2-cycle family. A holographic dual gauge theory, encoded via dimer diagrams, tracks the Seiberg cascades, complex deformations, and Higgs-induced splitting that separate the throat into two infrared sectors, while enabling a controlled treatment of fivebrane backreaction and warping. The authors relate the geometric construction to a Hanany–Witten T-dual picture, clarifying how axion monodromy arises and how backreaction scales with flux quanta, showing it can be kept subdominant under COBE-normalized inflaton potentials. The explicit holographic framework thus provides a robust, calculable platform for studying backreaction and warp effects in axion monodromy models, with potential implications for UV completions and future explorations of warped-brane inflation scenarios.

Abstract

We construct a simple explicit local geometry providing a `bifid throat' for 5-brane axion monodromy. A bifid throat is a throat that splits into two daughter throats in the IR, containing a homologous 2-cycle family reaching down into each daughter throat. Our example consists of a deformed $\mathbb{Z}_3\times\mathbb{Z}_2$ orbifold of the conifold, which provides us with an explicit holographic dual of the bifid throat including D3-branes and fractional 5-branes at the toric singularities of our setup. Having the holographic description in terms of the dual gauge theory allows us to address the effect of 5-brane-antibrane pair backreaction including the warping effects. This leads to the size of the backreaction being small and controllable after imposing proper normalization of the inflaton potential and hence the warping scales.

Figures (22)

• Figure 1: Sketch of the bifid throat. The dashed line denotes the 3-chain showing that the two 2-cycles are homologous.
• Figure 2: (a) Web diagram of the singularity of interest; for the sake of clarity we have depicted the collapsed 2-cycles of finite size. (b) Toric diagram, where the initiated easily recognizes an orbifold of the conifold. (c) Splitting of the web diagram displaying the three complex deformations of the geometry, and the three corresponding 3-cycles.
• Figure 3: The dimer describing the gauge theory for the underlying system of D3-branes at the singular geometry in Figure \ref{['webdiagram']}. It corresponds to enlarging the unit cell in the infinite periodic array corresponding to the conifold dimer.
• Figure 4: Zig-zag paths in the dimer, and picture of the external legs in the web diagram as obtained from their $(p,q)$-classes after a $SL(2,\mathbb{Z})$ transformation.
• Figure 5: (a) Web diagram for the inital curves-of-conifolds geometry of Aganagic et al. Aganagic:2006ex. (b) The deformation $W'(x)$ leading to two conifolds connected by a 2-cycle family related in homology.