A tip for landscape riders: multi-field inflation can fulfill the swampland distance conjecture

Bravo, Rafael; Palma, Gonzalo A.; Riquelme, Simon

doi:10.1088/1475-7516/2020/02/004

Cited by 36 publications

(25 citation statements)

References 100 publications

(163 reference statements)

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“…Otherwise a tower of light states emerges which would spoil the low energy effective description. A recent discussion on multifield inflation and the DSC has appeared in [40]. So here we simply stress that inflationary trajectories with large turning rates Ω/H 1 differ strongly from a geodesic and thus (2.36) does not apply.…”

Section: Fat Inflation and The Swamplandmentioning

confidence: 90%

Fat inflatons, large turns and the η-problem

Chakraborty

Chiovoloni

Loaiza-Brito

et al. 2020

J. Cosmol. Astropart. Phys.

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It is commonly believed that a successful period of inflation driven by a single or several scalar fields requires a specific hierarchy of masses given by M inf H M heavy , where M inf can correspond to several or a single light field and M heavy corresponds to any heavy field that might be integrated out if it satisfies suitable conditions. This is at the heart of the so called η-problem in inflation, since large contributions to the masses of the inflatons might spoil the slow-roll conditions required for inflation. We show that, while this is an unavoidable conclusion in single field inflation, in multifield inflation, heavy fields as defined above, may be fully responsible for a successful period of what we call fat slow-roll inflation. Moreover we show that in this scenario, the turning rate of the inflationary trajectory, Ω/H, is larger than one. Thus, the η-problem is evaded with large turns in fat inflation. Depending on the perturbations' mass spectra, cosmological predictions will differ either slightly or largely with respect to those of the single field case. We illustrate this scenario in a concrete example in Type IIB string flux compactifications, where a probe D5-brane moving along the angular and radial directions in a warped throat drives fat D5-brane natural inflation. An instantaneous superplanckian decay constant can be defined, consistent with our low energy approximations, thanks to the strong warping of the geometry. We compute the cosmological observables, which differ from the single field case. We also discuss fat inflation in the context of recently proposed swampland de Sitter conjectures.

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Section: Fat Inflation and The Swamplandmentioning

confidence: 90%

Fat inflatons, large turns and the η-problem

Chakraborty

Chiovoloni

Loaiza-Brito

et al. 2020

J. Cosmol. Astropart. Phys.

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“…Usually in the curved field manifold the inflaton trajectory may demonstrate turning dynamics (or equivalently non-geodesic motion in the field space). It has also been suggested that such kind of multi-field behaviour may be free from some possible problems faced by single field inflation [56][57][58]. Moreover, richer phenomenology emerges in this class of multi-field models, which could be interesting for future observational detections.…”

Section: Introductionmentioning

confidence: 99%

On the inflationary massive field with a curved field manifold

Wang

2020

J. Cosmol. Astropart. Phys.

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Massive fields during inflation provide an interesting opportunity to test new physics at very high energy scales. Meanwhile in fundamental realizations, the inflationary field space typically has a curved geometry, which may leave detectable imprints in primordial observables. In this paper we study an extension of quasi-single field inflation where the inflaton and the massive field belong to a curved field manifold. Because of the nontrivial field space curvature, the massive field here can get significant mass corrections of order the Hubble scale, thus the quasi-single field predictions on primordial non-Gaussianity are affected. We derive the same result in an equivalent approach by using the background effective field theory of inflation, where a dimension-6 operator is identified to play an important role and its cutoff scale is associated with the curvature scale of the field space. In addition, due to the slow-roll evolution of the inflaton, this type of mass correction has intrinsic time-dependence. Consequently, the running mass modifies the scaling behaviour in the squeezed limit of the scalar bispectrum, while the resulting running index measures the curvature of the internal field space. Therefore the minimal setup of a massive field within curved field space during inflation may naturally lead to new observational signatures of the field space geometry.

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“…However, it has been shown that if the background cosmology for single field inflation is not GR based, then this inflationary regime can still satisfy the swampland criterion [30][31][32][33][34]. Multi field inflationary models are consistent with the conjectures even in GR based paradigms [35]. It's also worth noting that in both GR and non-GR based cosmologies, the warm inflation paradigm has been shown to be very compatible with the swampland criterion even for single field models [36][37][38][39][40] The recently proposed "Trans Planckian Censorship Conjecture" (TCC) [41] is another swampland conjecture that has sparked a lot of interest in inflationary cosmology .…”

Section: Introductionmentioning

confidence: 84%

Lorentz violating inflation and the Swampland

Trivedi

2021

Preprint

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The swampland conjectures from String theory have had very interesting implications for cosmology and particularly for Inflation. It has been shown that the single field inflationary models in a GR based cosmology are in unavoidable tensions with these conjectures, while these single field models can still be consistent in certain non-trivial inflationary regimes. So it becomes interesting to see whether there is a way to overcome the issues of the swampland and single field inflation in an essentially GR based cosmology. We show that this can indeed be the case and for this, we consider a certain type of Lorentz violating inflationary scenario. We work out the swampland bounds for Lorentz violating inflationary models after which show that inflationary models which would have had otherwise serious tensions with these conjectures in a usual GR based scenario, can be very tranquil with the criterion in this regime. For this we take examples of Higgs inflation, radion gauge inflation and Spontaenous symmetry breaking inflation and show that the bounds imposed by the swampland on the Lorentz violating parameter can be easily satisfied in these models.

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A tip for landscape riders: multi-field inflation can fulfill the swampland distance conjecture

Cited by 36 publications

References 100 publications

Fat inflatons, large turns and the η-problem

Fat inflatons, large turns and the η-problem

On the inflationary massive field with a curved field manifold

Lorentz violating inflation and the Swampland

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