Cosmic Optical Activity in a Randall-Sundrum Braneworld with Bulk Kalb-Ramond field

TL;DR

This paper investigates how a string-inspired Kalb-Ramond field in a Randall-Sundrum braneworld amplifies optical activity of electromagnetic waves, revealing potential conflicts with astrophysical observations due to excessive predicted polarization rotation.

Contribution

It explicitly calculates the coupling between Kalb-Ramond and electromagnetic fields in a Randall-Sundrum model, showing significant enhancement of optical rotation effects.

Findings

Enormous enhancement of optical rotation in the Randall-Sundrum scenario.

Conflict with astrophysical observations due to predicted large polarization rotation.

Potential constraints on braneworld models from optical activity measurements.

Abstract

Optical activity of electromagnetic waves in a string inspired Kalb-Ramond cosmological background is studied in presence of extra spacetime dimension. The Kalb-Ramond-electromagnetic coupling which originates from the gauge anomaly cancelling Chern-Simons term in a string inspired model, is explicitly calculated following Randall-Sundrum braneworld conjecture. It is shown that the Randall-Sundrum scenario leads to an enormous enhancement of the optical rotation of a plane polarized electromagnetic wave propagating on the visible brane.Absence of any experimental support in favour of such a large rotation in astrophysical experiments on distant galactic radio waves indicates an apparent conflict between Randall-Sundrum brane world scenario and the presence of Kalb-Ramond antisymmetric tensor field in the background spacetime.