Chiral anomalous dispersion

Abstract

Abstract:The linearized Einstein equation describing graviton propagation through a chiral medium appears to be helicity dependent. We analyze features of the corresponding spectrum in a collision-less regime above a flat background. In the long wave-length limit, circularly polarized metric perturbations travel with a helicity dependent group velocity that can turn negative giving rise to a new type of an anomalous dispersion. We further show that this chiral anomalous dispersion is a general feature of polarized modes propagating through chiral plasmas extending our result to the electromagnetic sector.

Chiral gravitational effect in time-dependent backgrounds

“…non-local thermal corrections, found in refs. [48,64] in the anomalous responses. The term induced by the chiral asymmetry (eq.…”

“…While the cosmological application of the CME is now being investigated in detail, its gravitational counterpart referred as "chiral gravitational effect" [48] has not been extensively investigated so far. In the case of chiral gravitational effect, the graviton (the transverse and traceless part of the metric perturbation) receives parity-violating vacuum polarization from the chiral asymmetry in the system, which leads to the anomalous contribution to the energy momentum tensor.…”

“…Before investigating the chiral gravitational effect in realistic cosmological setups, one needs to extend the formulation in the previous study. One of the pioneer works on the chiral gravitational effect [48] considered this effect in the static thermal fermion background with a chiral asymmetry, based on refs. [64,65] where an anomalous dispersion relation of the gravitational waves in such a background is derived.…”

“…We first discuss the gravitational parity-violating effect in a chiral asymmetric fermion background, which is referred as the chiral gravitational effect in ref. [48], focusing on the Minkowski spacetime background for simplicity. In order to consider this phenomenon in a cosmological setup, e.g.…”

“…The chiral gravitational effect in a static thermal background has been studied in ref. [48], where the authors particularly focused on the anomalous corrections to the dis-…”