Compensation for large tensor modes with iso-curvature perturbations in CMB anisotropies

Understand

Recently, BICEP2 has reported the large tensor-to-scalar ratio $r=0.2^{+0.07}_{-0.05}$ from the observation of the cosmic microwave background (CMB) B-mode at degree-scales.

• Since tensor modes induce not only CMB B-mode but also the temperature fluctuations on large scales, to realize the consistent temperature fluctuations with the Planck result we should consider suppression of scalar perturbations on corresponding large scales.
• To realize such a suppression, we consider anti-correlated iso-curvature perturbations which could be realized in the simple curvaton model.