Analytic parity-violating greybody factors of a dynamical Chern-Simons black hole
Abstract
We study the low-frequency scattering of gravitational and pseudoscalar waves off a non-rotating black hole in dynamical Chern-Simons (dCS) gravity, where the axial (odd-parity) gravitational sector is irreducibly coupled to the dynamical pseudoscalar while the polar sector remains general relativistic. Working to first order in the dimensionless coupling zeta = (ell_CS/M)^4 and using matched asymptotic expansions, we obtain an exact closed form for the graviton-to-pseudoscalar conversion probability, d_2 = 3(pi^2-9)^2/8, and a high-precision reconstruction, in a proven transcendental basis, of the graviton greybody (absorption) asymmetry, kappa_2 = (21/80) pi^4 + (27/8) pi^2 - 89833/1536, for the quadrupole (ell=2) channel. Both reduce to combinations of pi^4, pi^2, and rational numbers, with no ln2 or odd-zeta terms in the reconstructed basis; the transmission-phase sector, by contrast, contains an analytically derived zeta(3)-9/8 static integral, while its overall matching prefactor is identified numerically. The leading reflection-phase asymmetry vanishes, so that no polarization rotation is imprinted on the reflected wave at leading low-frequency order, while a subleading O(omegazeta) asymmetry remains in the transmitted phase. The normalized flux asymmetries are numerically consistent with a 1/(Momega)^2 falloff in the geometric-optics limit, where the leading remaining flux effect is conversion loss. The matched-asymptotic results are checked against direct two-channel integration, while the one-dimensional integral determining kappa_2 is evaluated to high precision within an analytically controlled transcendental basis. The results provide analytic targets linking dCS parity violation in absorption and mode conversion to the axial/polar quasinormal-mode splitting.
Related
- CosmoDyn: a semi-analytic post-processing framework for the dynamical evolution of compact stellar systems and black holes in cosmological simulations
- Gravitational-Wave Echoes and Greybody Cutoff from Logarithmic Throats at a Marginal-Trapping Threshold
- Probing Lorentz-violating scalar forces and dark matter with precision matter and antimatter experiments
- Relativistic Magnetohydrodynamics from Myers-Pospelov Lorentz-Violating Electrodynamics
- Primordial Tensor Signatures and Gravitational Wave Constraints in Lorentz Violating Inflation with Non-Canonical Kinetics
BibTeX
@misc{rout2026analytic,
title = {{Analytic parity-violating greybody factors of a dynamical Chern-Simons black hole}},
author = {Abhishek Rout},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10280},
eprint = {2610.10280},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10280},
}
RIS
TY - UNPB
TI - Analytic parity-violating greybody factors of a dynamical Chern-Simons black hole
AU - Abhishek Rout
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10280
UR - https://arxiv.org/abs/2610.10280
AB - We study the low-frequency scattering of gravitational and pseudoscalar waves off a non-rotating black hole in dynamical Chern-Simons (dCS) gravity, where the axial (odd-parity) gravitational sector is irreducibly coupled to the dynamical pseudoscalar while the polar sector remains general relativistic. Working to first order in the dimensionless coupling zeta = (ell_CS/M)^4 and using matched asymptotic expansions, we obtain an exact closed form for the graviton-to-pseudoscalar conversion probability, d_2 = 3(pi^2-9)^2/8, and a high-precision reconstruction, in a proven transcendental basis, of the graviton greybody (absorption) asymmetry, kappa_2 = (21/80) pi^4 + (27/8) pi^2 - 89833/1536, for the quadrupole (ell=2) channel. Both reduce to combinations of pi^4, pi^2, and rational numbers, with no ln2 or odd-zeta terms in the reconstructed basis; the transmission-phase sector, by contrast, contains an analytically derived zeta(3)-9/8 static integral, while its overall matching prefactor is identified numerically. The leading reflection-phase asymmetry vanishes, so that no polarization rotation is imprinted on the reflected wave at leading low-frequency order, while a subleading O(omegazeta) asymmetry remains in the transmitted phase. The normalized flux asymmetries are numerically consistent with a 1/(Momega)^2 falloff in the geometric-optics limit, where the leading remaining flux effect is conversion loss. The matched-asymptotic results are checked against direct two-channel integration, while the one-dimensional integral determining kappa_2 is evaluated to high precision within an analytically controlled transcendental basis. The results provide analytic targets linking dCS parity violation in absorption and mode conversion to the axial/polar quasinormal-mode splitting.
ER -