Generation of CMB B-mode Polarization from Circular Polarization

TL;DR

This paper explores how non-zero circular polarization in the CMB, caused by new interactions, can generate B-mode polarization without tensor perturbations, by modifying the Boltzmann equations for Stokes parameters.

Contribution

It introduces a novel mechanism where circular polarization can produce B-mode polarization in the CMB independently of tensor perturbations.

Findings

Circular polarization can generate B-mode polarization.

New interactions can induce non-zero circular polarization.

B-mode can arise without tensor perturbations.

Abstract

In this work we consider non-zero circular polarization for the CMB radiation as a result of new interactions. We then rewrite the Boltzmann equations for the Stokes parameters $Q$, $U$ and $V$ and show that the circular polarization can generate the B-mode polarization even if no tensor perturbations are present.