Implications of Planck results for models with local type non-Gaussianity

Suyama, Teruaki; Takahashi, Tomo; Yamaguchi, Masahide; Yokoyama, Shuichiro

doi:10.1088/1475-7516/2013/06/012

Cited by 19 publications

(20 citation statements)

References 61 publications

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“…Moreover, the shape and size of non-gaussianity predicted by more complicated models depend on the types of modifications considered, thus deeming it a very useful discriminant. The recent Planck results, which are still consistent with gaussian fluctuations, put tight constraints on inflationary models predicting large non-gaussianity, but still allow for deviations from the simplest of single-field scenarios [3][4][5]7].…”

Section: Introductionmentioning

confidence: 99%

Non-linear curvature perturbation in multi-field inflation models with non-minimal coupling

White

Minamitsuji

Sasaki

2013

J. Cosmol. Astropart. Phys.

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Abstract. Using the δN formalism we consider the non-linear curvature perturbation in multi-field models of inflation with non-minimal coupling. In particular, we focus on the relation between the δN formalism as applied in the conformally related Jordan and Einstein frames. Exploiting results already known in the Einstein frame, we give expressions for the power spectrum, spectral tilt and non-gaussianity associated with the Jordan frame curvature perturbation. In the case that an adiabatic limit has not been reached, we find that in general these quantities differ from those associated with the Einstein frame curvature perturbation, and also confirm their equivalence in the absence of isocurvature modes. We then proceed to consider two analytically soluble examples, the first involving a non-minimally coupled 'spectator' field and the second being a non-minimally coupled extension of the multi-brid inflation model. In the first model we find that predictions can easily be brought into agreement with the recent Planck results, as the tensor-to-scalar ratio is generally small, the spectral tilt tuneable and the non-gaussianity suppressed. In the second model we find that predictions for all three parameters can differ substantially from those predicted in the minimally coupled case, and that the recent Planck results for the spectral tilt can be used to constrain the non-minimal coupling parameters.

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Section: Introductionmentioning

confidence: 99%

Non-linear curvature perturbation in multi-field inflation models with non-minimal coupling

White

Minamitsuji

Sasaki

2013

J. Cosmol. Astropart. Phys.

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“…Now, PLANCK data put a stringent constraint on f NL , however, a non-Gaussian signature of primordial density perturbation may come from a higher order one (see Ref. [7] for such an example). In such a case, the results presented in this article should be useful to investigate such a scenario.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…In particular, in some models, large values of g NL are possible even when f NL satisfies the PLANCK constraint [7]. In fact, when g NL is large, it can contribute to the total value of f NL through higher order correlation functions, or what is often called loop correction [8].…”

Section: Introductionmentioning

confidence: 99%

Higher order nonlinear parameters with Planck constraints

Gong

Takahashi

2014

Phys. Rev. D

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We investigate how higher order non-linear parameters affect lower order ones through loop effects. We calculate the loop corrections up to two-loops and explicitly show that the tree contribution is stable against loop terms in most cases. We argue that, nevertheless, observational constraints on non-linear parameters such as f NL and τ NL can also give a limit even for higher order ones due to the loop contribution. We discuss these issues for both single-source and multi-source cases.

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“…Thus, a lot of conversion mechanisms have been proposed to generate large non-Gaussianities [9]. Unfortunately, recent observations of the CMB anisotropies by the Planck satellite disfavored large local type f NL [12], which strongly constrains each local type model [13]. However, it should be stressed that, for wide parameter regions in many local models, f NL can be of order unity, which significantly deviates from the predictions (∼ O(0.01)) of single field inflations and is still allowed from the Planck results.…”

Section: Non-gaussianities Of Curvature Perturbationsmentioning

confidence: 99%

Cosmic Acceleration in the Early and Present Universe

Yamaguchi

2014

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

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Cosmic accelerations in the early and present Universe play essentially important roles to determine the evolution, structure, and destiny of the Universe. Therefore, to identify the origins of cosmic accelerations is one of the most ultimate goals of cosmology. In this award talk for the C. N. Yang Award, I introduced my achievements on this mystery. First of all, we gave a natural mechanism to cause chaotic inflation, which is the most natural inflation model but had never been realized in the context of realistic particle physics for almost twenty years. We introduced a Nambu-Goldstone-like shift symmetry, which is now recognized as a key feature to control the Planck-scale physics, and solved the long standing difficulties to realize chaotic inflation. Second, we found a generic relation (now called Suyama-Yamaguchi inequality) between higher order correlations of the curvature perturbations, which is quite useful to identify what fields are actually responsible for the origin of primordial fluctuation. Finally, we mention our proposal (now called k-essence) for the present cosmic acceleration.

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Implications of Planck results for models with local type non-Gaussianity

Cited by 19 publications

References 61 publications

Non-linear curvature perturbation in multi-field inflation models with non-minimal coupling

Non-linear curvature perturbation in multi-field inflation models with non-minimal coupling

Higher order nonlinear parameters with Planck constraints

Cosmic Acceleration in the Early and Present Universe

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