2014/04/21 by Razieh Emami, Hassan Firouzjahi, Yi Wang · 1 citation
Physics and Astronomy · #astro-ph.CO #hep-th
paper · pdf · doi:10.1103/physrevd.90.021301
published as Phys. Rev. D 90, 021301 (2014) · 3 pages, no figure
arxiv created 2014/04/21 · arxiv updated 2014/08/06
We examine the recent proposal [1] that the anti-cross-correlation of the scalar and tensor primordial fluctuations reconciles the tension between BICEP2 and Planck observations. We show that unfortunately the contribution from the scalar-tensor correlation to the CMB temperature power spectrum vanishes once summed over the angular mode m so the tension between BICEP2 and Planck can not be reconciled. The reason is that one has to use the spin-weighted spherical harmonics when projecting fields with nonzero spins into the CMB sky. These nonzero spin-weighted spherical harmonics are subject to orthogonality conditions when summed over the angular direction and thus the desired cross-correlation between the scalar and tensor perturbations in CMB map vanishes.