# Weak Lensing Effect on CMB in the Presence of a Dipole Anisotropy

## TL;DR

This paper studies how weak gravitational lensing affects the cosmic microwave background when a dipole anisotropy exists, revealing notable impacts on B-mode polarization at large scales.

## Contribution

It introduces a method to calculate lensing effects on CMB in the presence of dipole anisotropy, focusing on the flat-sky approximation and deriving relevant correction functions.

## Key findings

- Significant correction to B-mode power spectrum at low multipoles.
- Temperature and E-mode spectra remain largely unaffected.
- Provides analytical expressions for lensing corrections in anisotropic conditions.

## Abstract

We investigate weak lensing effect on cosmic microwave background (CMB) in the presence of dipole anisotropy. The approach of flat-sky approximation is considered. We determine the functions $\sigma_0^2$ and $\sigma_2^2$ that appear in expressions of the lensed CMB power spectrum in the presence of a dipole anisotropy. We determine the correction to B-mode power spectrum which is found to be appreciable at low multipoles ($l$). However, the temperature and E-mode power spectrum are not altered significantly.