Journal of High Energy Physics

, 2014:123 | Cite as

The powers of monodromy

  • Liam McAllister
  • Eva Silverstein
  • Alexander Westphal
  • Timm WraseEmail author
Open Access


Flux couplings to string theory axions yield super-Planckian field ranges along which the axion potential energy grows. At the same time, other aspects of the physics remain essentially unchanged along these large displacements, respecting a discrete shift symmetry with a sub-Planckian period. After a general overview of this monodromy effect and its application to large-field inflation, we present new classes of specific models of monodromy inflation, with monomial potentials μ 4−p ϕ p . A key simplification in these models is that the inflaton potential energy plays a leading role in moduli stabilization during inflation. The resulting inflaton-dependent shifts in the moduli fields lead to an effective flattening of the inflaton potential, i.e. a reduction of the exponent from a fiducial value p 0 to p < p 0. We focus on examples arising in compactifications of type IIB string theory on products of tori or Riemann surfaces, where the inflaton descends from the NS-NS two-form potential B 2, with monodromy induced by a coupling to the R-R field strength F 1. In this setting we exhibit models with p = 2/3, 4/3, 2, and 3, corresponding to predictions for the tensor-to-scalar ratio of r ≈ 0.04, 0.09, 0.13, and 0.2, respectively. Using mirror symmetry, we also motivate a second class of examples with the role of the axions played by the real parts of complex structure moduli, with fluxes inducing monodromy.


Cosmology of Theories beyond the SM Flux compactifications 


Open Access

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Copyright information

© The Author(s) 2014

Authors and Affiliations

  • Liam McAllister
    • 1
  • Eva Silverstein
    • 2
    • 3
    • 4
  • Alexander Westphal
    • 5
  • Timm Wrase
    • 2
    Email author
  1. 1.Department of PhysicsCornell UniversityIthacaU.S.A.
  2. 2.Stanford Institute for Theoretical PhysicsStanford UniversityStanfordU.S.A.
  3. 3.SLAC National Accelerator LaboratoryMenlo ParkU.S.A.
  4. 4.Kavli Institute for Particle Astrophysics and CosmologyStanfordU.S.A.
  5. 5.Deutsches Elektronen-Synchrotron DESY, Theory GroupHamburgGermany

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