Lensing reconstruction of primordial cosmic microwave background polarization

We discuss the possibility to directly reconstruct the cosmic microwave background (CMB) polarization field at the last scattering surface by accounting for modifications imposed by the gravitational lensing effect. The suggested method requires a tracer field of the large scale structure lensing potentials that deflected propagating CMB photons from the last scattering surface. This required information can come from a variety of observations on the large scale structure matter distribution, including the convergence reconstructed from lensing shear studies involving galaxy shapes. In the case of so-called curl, or B modes of CMB polarization, the reconstruction allows one to identify the distinct signature of inflationary gravitational waves.