Constraints on large-scale CMB EB correlations from Planck polarization

We analyze large-scale parity-odd EB correlations in the cosmic microwave background using Planck 2018 polarization data. Employing the SMICA component-separated maps, conservative sky masking, and Monte Carlo null simulations, we find no statistically significant deviation from the parity-symmetric expectation. From the null distribution, we place a two-sided 95% confidence-level upper bound on the magnitude of coherent, multipole-averaged correlations on large angular scales, |⟨CEB ℓ ⟩| < 1.04 × 10−12 μK2 for 2 ≤ ℓ ≤ 30. These results provide robust, model-independent null constraints on parity-violating signatures in the largest-scale CMB polarization field.