Axion monodromy inflation with warped KK-modes

Self Cite

We argue that a new type of extremely light axion is generically present in the type IIB part of the string theory landscape. Its mass is suppressed by the third power of the warp factor of a strongly warped region (Klebanov-Strassler throat), suggesting the name thraxion. Our observation is based on the generic presence of several throats sharing the same 2-cycle. This cycle shrinks to zero volume at the end of each throat. It is hence trivial in homology and the corresponding C 2 axion is massive. However, the mass is warping-suppressed since, if one were to cut off the strongly warped regions, a proper 2-cycle would re-emerge. Since the kinetic term of the axion is dominated in the UV, an even stronger, quadratic mass suppression results. Moreover, if the axion is excited, the angular modes of the throats backreact. This gives our effective C 2 axion a finite monodromy and flattens its potential even further. Eventually, the mass turns out to scale as the third power of the warp factor. We briefly discuss possible implications for phenomenology and potential violations of the Weak Gravity Conjecture for axions. Moreover we identify a mechanism for generating super-Planckian axionic field ranges which we call drifting monodromies. However, in the examples we consider, the potential oscillates on sub-Planckian distances in field space, preventing us from building a natural inflation model on the basis of this idea.

Section: Moduli Stabilization By Fluxesmentioning

confidence: 99%

“…Using the previous subsection and the results of [28], we collect the two actions 41 that will give us all relevant parameters. Note that we derive the action for ϕ for c = 0 and that the one for c for ϕ = 0.…”

Section: C2 Schrödinger Equations and Exact Solutions For Free Fieldsmentioning

confidence: 99%

Thraxions: ultralight throat axions

Hebecker

Leonhardt

Moritz

et al. 2019

Self Cite

“…A recently popular ALP is the relaxion [66,67] in which the minimal model has a mass as low as m a 10 −25 eV. In the formulation of relaxion in terms of 4-forms [68,69], the mass of the relaxion is given by m a = F 4 /f a , where F 4 (10 −3 eV ) 2 is the 4-form field strength. An ALP coupled to 4-forms (a hierarxion [70]) and the Higgs particle has also been recently suggested in order to construct a landscape of values for the Higgss mass.…”

Section: Axionsmentioning

confidence: 99%

Constraining neutrino masses, the cosmological constant and BSM physics from the weak gravity conjecture

Ibáñez

Lozano²,

Valenzuela

2017

It is known that there are AdS vacua obtained from compactifying the SM to 2 or 3 dimensions. The existence of such vacua depends on the value of neutrino masses through the Casimir effect. Using the Weak Gravity Conjecture, it has been recently argued by Ooguri and Vafa that such vacua are incompatible with the SM embedding into a consistent theory of quantum gravity. We study the limits obtained for both the cosmological constant Λ 4 and neutrino masses from the absence of such dangerous 3D and 2D SM AdS vacua. One interesting implication is that Λ 4 is bounded to be larger than a scale of order m 4 ν , as observed experimentally. Interestingly, this is the first argument implying a non-vanishing Λ 4 only on the basis of particle physics, with no cosmological input. Conversely, the observed Λ 4 implies strong constraints on neutrino masses in the SM and also for some BSM extensions including extra Weyl or Dirac spinors, gravitinos and axions. The upper bounds obtained for neutrino masses imply (for fixed neutrino Yukawa and Λ 4 ) the existence of upper bounds on the EW scale. In the case of massive Majorana neutrinos with a see-saw mechanism associated to a large scale M 10 10−14 GeV and Y ν 1 10 −3 , one obtains that the EW scale cannot exceed M EW 10 2 − 10 4 GeV. From this point of view, the delicate fine-tuning required to get a small EW scale would be a mirage, since parameters yielding higher EW scales would be in the swampland and would not count as possible consistent theories. This would bring a new perspective into the issue of the EW hierarchy.

“…Instead, 1 Although whether primordial gravitational waves can be realised within perturbative string theory remains an open question [7]. 2 For further recent studies on axion monodromy see [18][19][20][21] and in non-geometric compactifications [22][23][24].…”

Section: Jhep10(2016)082mentioning

confidence: 99%

“…Indeed, the Kähler potential is invariant under a shift symmetry, or more generally a monodromy along the argument of the complex structure, arg(z) → arg(z) + 2πn, which is broken spontaneously by the fluxes. A common simplification used in the literature to realise CS axion monodromy in these type of compactifications is to consider only the leading order term in the series expansion of the periods in terms of the CS moduli [21,27,34,35] when computing the scalar potential V = e K 2κ 2 10 g s…”

Section: Jhep10(2016)082mentioning

confidence: 99%

Mirror quintic vacua: hierarchies and inflation

Bizet

Loaiza-Brito

Zavala

2016

Abstract:We study the moduli space of type IIB string theory flux compactifications on the mirror of the CY quintic 3-fold in P 4 . We focus on the dynamics of the four dimensional moduli space, defined by the axio-dilaton τ and the complex structure modulus z. The z-plane has critical points, the conifold, the orbifold and the large complex structure with non trivial monodromies. We find the solutions to the Picard-Fuchs equations obeyed by the periods of the CY in the full z-plane as a series expansion in z around the critical points to arbitrary order. This allows us to discard fake vacua, which appear as a result of keeping only the leading order term in the series expansions. Due to monodromies vacua are located at a given sheet in the z-plane. A dS vacuum appears for a set of fluxes. We revisit vacua with hierarchies among the 4D and 6D physical scales close to the conifold point and compare them with those found at leading order in [1,2]. We explore slow-roll inflationary directions of the scalar potential by looking at regions where the multi-field slow-roll parameters and η are smaller than one. The value of depends strongly on the approximation of the periods and to achieve a stable value, several orders in the expansion are needed. We do not find realizations of single field axion monodromy inflation. Instead, we find that inflationary regions appear along linear combinations of the four real field directions and for certain configurations of fluxes.