Dilaton field and cosmic wave propagation

Understand

We study the electromagnetic wave propagation in the joint dilaton field and axion field.

• Dilaton field induces amplification/attenuation in the propagation while axion field induces polarization rotation.
• The amplification/attenuation induced by dilaton is independent of the frequency (energy) and the polarization of electromagnetic waves (photons).
• From observations, the agreement with and the precise calibration of the cosmic microwave background (CMB) to blackbody radiation constrains the fractional change of dilaton |{\Delta}{\psi}|/{\psi} to less than about 8 x 10^(-4) since the time of the last scattering surface of the CMB.