Spectral dependence of CMB polarization and parity

Abstract

The polarization of the cosmic microwave background radiation (CMBR) can serve as a probe for nonstandard parity violating interactions. Many such interactions are predicted in particle physics models arising from theories with extra dimensions such as superstring theory. These interactions produce an optical activity that depends on the space-time nature of the parity violating field. In particular, it is possible to obtain a frequency-dependent differential rotation of the polarization axis. The form of the frequency dependence is sensitive to the time evolution of the parity odd background field. Thus, one may be able to study a broad class of parity violating operators through polarization measurements of the CMBR.

CMB polarization systematics, cosmological birefringence, and the gravitational waves background

“…As we can see, even if one assumes a standard scenario where BB, T B and EB correlations are zero at the Last Scattering Surface (LSS), cosmic birefringence introduces a new BB component from EE. The above equations are exact for a constant rotation, and approximate very well the effects of a rotation angle varying with time if the time variation is sufficiently slow and the resulting total rotation after the propagation of photons (from LSS toward us) is sufficiently small, which is the case for most models of interest (see [13,14,15,16,18,19,20,21] 1 ). The final result is that B-modes polarization could therefore not only be sourced by gravitational waves but also from a completely different physics.…”

“…However, since the seminal paper by Carroll et al ([12]) the possibility of a cosmological birefringence, or in vacuo rotation of the polarization direction of a photon, has been considered by several authors (see e.g. [13,14,15,16,17,18,19,20,21] and references therein). Even if exotic, cosmological birefringence is therefore predicted by a wide class of non-standard models and provides information on symmetry violations and on pseudoscalar fields beyond the standard model.…”

Cosmological birefringence due to CPT-even Chern–Simons-like term with Kalb–Ramond and scalar fields

“…[49,50]. The major difference with our model is the introduction of a complete fermion current with a nontrivial gauge coupling.…”

Disentangling birefringence from standard physics in CMB measurements and distinguishing among production mechanisms

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] The main signal of parity-violation would be a correlation between parity-even (polarization E modes and temperature T modes) and parity-odd (polarization B modes) components of the CMB anisotropies. The power gained by the parity-violating correlation power spectra would result in a loss of power from the other ones (EE, TE, BB correlations).…”