Isocurvature perturbations and tensor mode in light of Planck and BICEP2

Abstract

We investigate the degeneracy of the isocurvature perturbations and the primordial gravitational waves, by using recent observations of the cosmic microwave background (CMB) reported by Planck and BICEP2 collaborations. We show that the tension in the bound on the tensor-to-scalar ratio $r$ between Planck and BICEP2 can be resolved by introducing the anti-correlated isocurvature perturbations. Quantitatively, we find that with the anti-correlated isocurvature perturbations the constraints on $r$ from Planck alone and BICEP2 results can be consistent at 68 % C.L.

16 pages, 7 figures, 1 table; accepted for publication in JCAP

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• Dynamical Fractional Chaotic Inflation -- Dynamical Generation of a Fractional Power-Law Potential for Chaotic Inflation
• Effect of transitions in the Planck mass during inflation on primordial power spectra
• Negative running prevents eternal inflation
• CDM/baryon isocurvature perturbations in a sneutrino curvaton model
• Constraining primordial vector mode from B-mode polarization
• Naturally large tensor-to-scalar ratio in inflation