Observational Viability of an Inflation Model with E-model Nonminimal Derivative Coupling

Nozari, Kourosh; Rashidi, Narges

doi:10.3847/1538-4357/aad18e

Cited by 22 publications

(9 citation statements)

References 65 publications

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“…We note that, instead of using the constraint on n and definition of the sound speed, one can use relation (25) and observationally viable values of r to obtain the observational constraint on the sound speed [86]. This constraint on the sound speed leads to the following constraint on the amplitude of the non-Gaussianity…”

Section: Power-law Inflation In Dbi Modelmentioning

confidence: 99%

Mimetic DBI Inflation in Confrontation with Planck2018 Data

Nozari

Rashidi

2019

ApJ

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We study mimetic gravity in the presence of a DBI-like term which is a non-canonical setup of the scalar field's derivatives. We consider two general cases with varying and constant sound speeds and construct the potentials for both the DBI and Mimetic DBI models. By considering the power-law scale factor as a = a 0 t n , we seek for the observational viability of these models. We show that, the Mimetic DBI model in some ranges of the parameters space is free of ghost and gradient instabilities. By studying r − n s and α s − n s behavior in confrontation with Planck2018 data, we find some constraints on the model's parameters. We show that for the case with varying sound speed, although power-law DBI inflation is not consistent with Planck2018 TT, TE, EE+low E+lensing data, but the Mimetic DBI inflation is consistent with Planck2018 TT, TE, EE+low E+lensing data at 95% CL, in some ranges of the model's parameters space as 40 ≤ n ≤ 55 where the model is instabilities-free in these ranges of parameters too. For the constant sound speed, by adopting some sample values of c s , we study both DBI and Mimetic DBI model numerically and find n ∼ 10 2 for DBI model and n ∼ 10 for Mimetic DBI model. We also compare the results with Planck2018 TT, TE, EE+low E+lensing+BK14+BAO data and see that the DBI and Mimetic DBI model with varying sound speed are ruled out with these joint data. However, these models with constant sound speed are consistent with Planck2018 TT, TE, EE+low E+lensing+BK14+BAO data with n ∼ 10 2 for DBI model and n ∼ 10 for Mimetic DBI model. In this case, we find some tighter constraints on the corresponding sound speed. PACS: 98.80. Bp, 98.80.Cq, 98.80.Es

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Section: Power-law Inflation In Dbi Modelmentioning

confidence: 99%

Mimetic DBI Inflation in Confrontation with Planck2018 Data

Nozari

Rashidi

2019

ApJ

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“…In the simple single field inflation model, we get the adiabatic, scale invariant and gaussian dominant modes of the primordial perturbations [1,2,3,4,5,6,7,8]. However, models with non-Gaussian distributed and not exactly scale invariant perturbations have attracted a lot of attentions [8,9,10,11,12,13,14,15,16,17,18,19,20,21].…”

Section: Introductionmentioning

confidence: 99%

Inflation in Energy-Momentum Squared Gravity in Light of Planck2018

Faraji¹,

Rashidi²,

Nozari³

2021

Preprint

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We study cosmological dynamics of the energy-momentum squared gravity. By adding the squared of the matter field's energy-momentum tensor (ζ T 2 ) to the Einstein Hilbert action, we obtain the Einstein's field equations and study the conservation law. We show that the presence of ζ T 2 term, breaks the conservation of the energy-momentum tensor of the matter fields. However, an effective energy-momentum tensor in this model is conserved in time. By considering the FRW metric as the background, we find the Friedmann equations and by which we explore the cosmological inflation in ζ T 2 model. We perform numerical analysis on the perturbation parameters and compare the results with Planck2018 different data sets at 68% and 95% CL, to obtain some constraints on the coupling parameter ζ. We show that for 0 < ζ ≤ 2.1 × 10 −5 , the ζ T 2 gravity is an observationally viable model of inflation.

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“…In this simple model, the dominant modes of the primordial perturbations are predicted to be scale-invariant, adiabatic and Gaussian [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]. However, there is a lot of attention to the extended inflation models predicting the non-Gaussian distributed perturbations [46][47][48][49][50][51][52][53][54][55].…”

Section: Introductionmentioning

confidence: 99%

Viable intermediate inflation in the mimetic DBI model

Rashidi

Nozari

2021

Eur. Phys. J. C

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We study the intermediate inflation in the mimetic Dirac–Born–Infeld model. By considering the scale factor as $$a=a_{0}\exp (bt^{\beta })$$ a = a 0 exp ( b t β ) , we show that in some ranges of the intermediate parameters b and $$\beta $$ β , the model is free of the ghost and gradient instabilities. We study the scalar spectral index, tensor spectral index, and the tensor-to-scalar ratio in this model and compare the results with Planck2018 TT, TE, EE + lowE + lensing + BAO + BK14 data at 68% and 95% CL. In this regard, we find some constraints on the intermediate parameters that lead to the observationally viable values of the perturbation parameters. We also seek the non-Gaussian features of the primordial perturbations in the equilateral configuration. By performing the numerical analysis on the nonlinearity parameter in this configuration, we show that the amplitude of the non-Gaussianity in the intermediate mimetic DBI model is predicted to be in the range $$-16.7<f^{equil}<-12.5$$ - 16.7 < f equil < - 12.5 . We show that, with $$0<b\le 10$$ 0 < b ≤ 10 and $$0.345<\beta <0.387$$ 0.345 < β < 0.387 , we have an instabilities-free intermediate mimetic DBI model that gives the observationally viable perturbation and non-Gaussianity parameters.

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Observational Viability of an Inflation Model with E-model Nonminimal Derivative Coupling

Cited by 22 publications

References 65 publications

Mimetic DBI Inflation in Confrontation with Planck2018 Data

Mimetic DBI Inflation in Confrontation with Planck2018 Data

Inflation in Energy-Momentum Squared Gravity in Light of Planck2018

Viable intermediate inflation in the mimetic DBI model

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