Attractor behaviour in multifield inflation

Carrilho, P.; Mulryne, David J.; Ronayne, J. W.; Tenkanen, Tommi

doi:10.1088/1475-7516/2018/06/032

Cited by 67 publications

(35 citation statements)

References 129 publications

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“…However, in our numerical analysis we do not use the approximate result (3.8) but compute everything using the exact result U (χ) = 5 Strictly speaking this applies only to the one-field case; for multi-field cases, see e.g. [34,64,69]. The form of the field redefinition also shows that in the Palatini case where κ = 0, no collider constraints on ξH similar to those derived in [75] can be obtained.…”

Section: Higgs-like Inflationmentioning

confidence: 98%

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Towards distinguishing variants of non-minimal inflation

Takahashi

Tenkanen

2019

J. Cosmol. Astropart. Phys.

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We study models of inflation where the scalar field φ that drives inflation is coupled non-minimally to gravity via ξφ 2 R, or where the gravity sector is enlarged by an R 2 term. We consider the original Higgs inflation, Starobinsky inflation, and two different versions of a scenario where the inflaton is a scalar field other than the Higgs, and discuss if they can be distinguished from each other by measuring the tensor-to-scalar ratio and runnings of the spectral index of primordial curvature perturbations, on top of the amplitude and spectral index of the perturbations. We consider both metric and Palatini theories of gravity, showing how detailed studies of non-minimally coupled models can help to identify the inflaton field and how they may provide for a way to also distinguish between different theories of gravity in the present context.1 As we will see, this does not necessarily amount to adding new degrees of freedom to the theory.

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Section: Higgs-like Inflationmentioning

confidence: 98%

“…[65,66,70,[80][81][82][83][84][85][86][87][88], and multifield models with non-minimal couplings to gravity in e.g. [36,64,69,89,90].…”

Section: )mentioning

confidence: 99%

Towards distinguishing variants of non-minimal inflation

Takahashi

Tenkanen

2019

J. Cosmol. Astropart. Phys.

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“…This was originally noted in Ref. [4] and has recently gained increasing attention [10,11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] (see also [30][31][32]). Interestingly, it was recently pointed out in Ref.…”

Section: Introductionmentioning

confidence: 97%

Minimal Higgs inflation with an R2 term in Palatini gravity

Tenkanen

2019

Phys. Rev. D

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It has recently been suggested that the Standard Model Higgs boson could act as the inflaton while minimally coupled to gravity -given that the gravity sector is extended with an αR 2 term and the underlying theory of gravity is of Palatini, rather than metric, type. In this paper, we revisit the idea and correct some shortcomings in earlier studies. We find that in this setup the Higgs can indeed act as the inflaton and that the tree-level predictions of the model for the spectral index and the tensor-to-scalar ratio are ns 0.941, r 0.3/(1 + 10 −8 α), respectively, for a typical number of e-folds, N = 50, between horizon exit of the pivot scale k = 0.05 Mpc −1 and the end of inflation. Even though the tensor-to-scalar ratio is suppressed compared to the usual minimally coupled case and can be made compatible with data for large enough α, the result for ns is in severe tension with the Planck results. We briefly discuss extensions of the model.

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“…This is due to the fact that most dynamics during reheating takes place 1 It is worth noting that in the Palatini formulation of gravity the behavior and predictions of ξ-attractor models change significantly, as is discussed for example in Refs. [7,8].…”

Section: Introductionmentioning

confidence: 99%

Universality and scaling in multi-field α-attractor preheating

Iarygina

Sfakianakis

Wang

et al. 2019

J. Cosmol. Astropart. Phys.

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We explore preheating in multi-field models of inflation in which the field-space metric is a highly curved hyperbolic manifold. One broad family of such models is called α-attractors, whose single-field regimes have been extensively studied in the context of inflation and supergravity. We focus on a simple two-field generalization of the T -model, which has received renewed attention in the literature. Krajewski et al. concluded, using lattice simulations, that multi-field effects can dramatically speed-up preheating. We recover their results and further demonstrate that significant analytical progress can be made for preheating in these models using the WKB approximation and Floquet analysis. We find a simple scaling behavior of the Floquet exponents for large values of the field-space curvature, that enables a quick estimation of the T -model reheating efficiency for any large value of the field-space curvature. In this regime we further observe and explain universal preheating features that arise for different values of the potential steepness. In general preheating is faster for larger negative values of the field-space curvature and steeper potentials. For very highly curved field-space manifolds preheating is essentially instantaneous.

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Attractor behaviour in multifield inflation

Cited by 67 publications

References 129 publications

Towards distinguishing variants of non-minimal inflation

Towards distinguishing variants of non-minimal inflation

Minimal Higgs inflation with an R2 term in Palatini gravity

Universality and scaling in multi-field α-attractor preheating

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