E-mode polarization
= E-mode polarization
{c}
{title2=$P_E$}
The parity-even part of linear sky polarization can be represented by a scalar potential $P_E$ through $Q\pm iU=\eth_{\pm}^2(P_E\pm iP_B)$. It is naturally separated from <B-mode polarization> by the parity of its spherical multipoles. Linear <scalar cosmological perturbations> generate E modes; the potential has an unobservable low-multipole kernel.