Abstract
We have studied primordial non-Gaussian features from a model of potential driven single field DBI Galileon inflation. We have computed the bispectrum from the three point correlation function considering all possible cross correlation between scalar and tensor modes from the proposed setup. Further, we have computed the trispectrum from four point correlation function considering the contribution from contact interaction, scalar and graviton exchange diagrams in the in-in picture. Finally we have obtained the non-Gaussian consistency conditions from the four point correlator, which results in partial violation of the Suyama-Yamaguchi four-point consistency relation. This further leads to the conclusion that sufficient primordial non-Gaussianities can be obtained from DBI Galileon inflation.
Highlights
We demonstrate that, in this framework, it is possible to have a parameter space for both non-Gaussianity and tensor-to-scalar ratio (r ) consistent with the combined constraint obtained from the Planck + WMAP9 + high-L + BICEP2 data [2,3,4,5]
The most impressing fact is that the upper bound of fNeqLu;i1l in the quasi-exponential limit is in good agreement with the combined constraint obtained from the Planck + WMAP9 + high-L + BICEP2 [2,3,4,5] data
Summing up all the significant contributions of the four-point four-scalar correlation coming from the contact interaction, scalar exchange, and graviton exchange interaction the numerical value of τNeqLuil in the equilateral limit is obtained from our setup as 48 < τNeqLuil < 97 in the quasi-exponential limit within the window for tensor-toscalar ratio 0.213 < r < 0.250 which is significantly large from other class of DBI models and consistent with the combined constraint obtained from the Planck +WMAP9+highL+BICEP2 [2,3,4,5] data
Summary
Where ρφ plays the role of energy density of the inflation in 4D effective theory, g1 represents the effective 4D Gauss– Bonnet coupling dependent function on FLRW background which can be expressed in terms of the brane tension of. More precisely one can interpret this to be a non-perturbative solution of the effective field theory where the effective coupling parameter l4 >> l1. The effective Friedmann equation in 4D takes a nontrivial form in the high energy regime, where energy density of the inflaton ρφ ≈ V (φ) >> g1 of D3 − D3 system. Eq (2.7) implies that within our prescribed setup the non-perturbative regime of effective field theory cannot able to produce the well-known solutions of GR in the low energy limiting situation where ρφ ≈ V (φ)
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