Efficient diagrammatic computation method for higher order correlation functions of local type primordial curvature perturbations

Abstract. We calculate the squeezed limit of the bispectrum produced by inflation with multiple light fields. To achieve this we allow for different horizon exit times for each mode and calculate the intrinsic field-space three-point function in the squeezed limit using softlimit techniques. We then use the δN formalism from the time the last mode exits the horizon to calculate the bispectrum of the primordial curvature perturbation. We apply our results to calculate the spectral index of the halo bias, n δb , an important observational probe of the squeezed limit of the primordial bispectrum and compare our results with previous formulae. We give an example of a curvaton model with n δb ∼ O(n s − 1) for which we find a 20% correction to observable parameters for squeezings relevant to future experiments. For completeness, we also calculate the squeezed limit of three-point correlation functions involving gravitons for multiple field models.

show abstract

“…Objects like the Γ matrices have been used by a number of authors in the past 8 [58,[68][69][70][71][72][73][74], and we note the properties:…”

Section: Field Evolution Between Different Crossing Timesmentioning

confidence: 99%

The squeezed limit of the bispectrum in multi-field inflation

Kenton

Mulryne

2015

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…Recently, non-Gaussianity of the primordial perturbation also has been studied by many authors [7,8,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48]. The main reason for non-Gaussianity to attract much attention is the expectation to future observations mentioned above.…”

Section: Further Steps From Observationsmentioning

confidence: 99%

“…A systematic derivation for more general formula, including higher order correlators, is given in Ref. [24]. Assuming that the initial perturbations of fields are Gaussian in the following form…”

Section: Non-gaussianity Produced During Inflationmentioning

confidence: 99%

Use of δ N formalism—difficulties in generating large local-type non-Gaussianity during inflation

Tanaka¹,

Suyama²,

Yokoyama³

2010

Class. Quantum Grav.

Self Cite

View full text Add to dashboard Cite

Abstract. We discuss generation of non-Gaussianity in density perturbation through the super-horizon evolution during inflation by using the so-called δN formalism. We first provide a general formula for the non-linearity parameter generated during inflation. We find that it is proportional to the slow-roll parameters, multiplied by the model dependent factors that may enhance the non-Gaussianity to the observable ranges. Then we discuss three typical examples to illustrate how difficult to generate sizable non-Gaussianity through the super-horizon evolution during inflation. First example is the double inflation model, which shows that temporal violation of slow roll conditions is not enough for the generation of non-Gaussianity. Second example is the ordinary hybrid inflation model, which illustrates the importance of taking into account perturbations on small scales. Finally, we discuss Kadota-Stewart model. This model gives an example in which we have to choose rather unnatural initial conditions even if large non-Gaussianity can be generated.

show abstract

“…For the sake of concreteness, we consider the inflationary model based on the supersymmetric seesaw model, which is dubbed the supersymmetric Higgs-lepton inflation (HLI) model [18][19][20], Also, we focus on the twofield case for simplicity. To compute the fluctuation spectrum of the inflationary model, we use the backward formulation [21][22][23] of the <5/V-formalism [24][25][26][27][28][29]. We find by numerical computations that the bispectrum of the inflationary model is susceptible to a change of the inflaton trajectory, a fact known in generic cases; see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

Testing supersymmetric Higgs inflation with non-Gaussianity

Kawai

Kim

2015

Phys. Rev. D

View full text Add to dashboard Cite

We investigate multi-field signatures of the nonminimally coupled supersymmetric Higgs inflation-type cosmological scenario, focusing on the two-field Higgs-lepton inflation model as a concrete example. This type of inflationary model is realized in a theory beyond the Standard Model embedded in supergravity with a noncanonical K\"{a}hler potential. We employ the backward $\delta N$ formalism to compute cosmological observables, including the scalar and tensor power spectra, the spectral indices, the tensor-to-scalar ratio and the local-type nonlinearity parameter. The trajectory of the inflaton is controlled by the initial conditions of the inflaton as well as by the coefficients in the K\"{a}hler potential. We analyze the bispectrum of the primordial fluctuations when the inflaton trajectory deviates from a straight line, and obtain constraints on the noncanonical terms of the K\"{a}hler potential using the Planck satellite data. Our analysis represents a concrete particle phenomenology-based case study of inflation in which primordial non-Gaussianities can reveal aspects of supergravity.Comment: 16 pages, 8 figures, revtex4. v2: typos corrected, comments and references added, version to be published, v3: typos correcte

show abstract

Efficient diagrammatic computation method for higher order correlation functions of local type primordial curvature perturbations

Cited by 25 publications

References 28 publications

The squeezed limit of the bispectrum in multi-field inflation

The squeezed limit of the bispectrum in multi-field inflation

Use of δ N formalism—difficulties in generating large local-type non-Gaussianity during inflation

Testing supersymmetric Higgs inflation with non-Gaussianity

Contact Info

Product

Resources

About