Cosmological observables in multi-field inflation with a non-flat field space

Abstract

Using $\delta N$ formalism, in the context of a generic multi-field inflation driven on a non-flat field space background, we revisit the analytic expressions of the various cosmological observables such as scalar/tensor power spectra, scalar/tensor spectral tilts, non-Gaussianity parameters, tensor-to-scalar ratio, and the various runnings of these observables. In our backward formalism approach, the subsequent expressions of observables automatically include terms beyond the leading order slow-roll expansion correcting many of the expression at subleading order. To connect our analysis properly with the earlier results, we rederive the (well) known (single field) expressions in the limiting cases of our generic formulae. Further, in the light of PLANCK results, we examine for the compatibility of the consistency relations within the slow-roll regime of a two-field roulette poly-instanton inflation realized in the context of large volume scenarios.

version 2, 32 pages, 1 table and 12 figures, major revision as per referee's suggestions, to appear in JCAP

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• A Systematic Approach to Kähler Moduli Stabilisation
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• Two-field axion inflation and the swampland constraint in the flux-scaling scenario
• Scale-dependent non-Gaussianity and the CMB Power Asymmetry
• Testing supersymmetric Higgs inflation with non-Gaussianity
• Fractional chaotic inflation in the lights of PLANCK and BICEP2
• Higher Derivative Corrections to String Inflation
• Exploring the inflation of $F(R)$ gravity
• Inflating in perturbative LVS: Global Embedding and Robustness
• Poly-instanton axion inflation
• Running of scalar spectral index in multi-field inflation
• Global Embedding of Fibre Inflation in Perturbative LVS
• Assisted Fibre Inflation in Perturbative LVS