Resonant Gravitational Production of Chiral Dark Photons
Abstract
Vector fields with a chiral, parity-odd coupling to a pseudoscalar field are known to undergo resonant amplification. In this work, we study this phenomenon in the context of cosmological gravitational particle production during early-universe inflation. We consider a massive vector (dark photon) field with a parity-odd coupling to the inflaton. There are two regimes of production, delineated by the relative size of the coupling and the dark photon mass, arising from a tachyonic instability, and a parametric resonance, respectively. As a result of the coupling, the transverse modes, subdominant in both the minimally and nonminimally coupled theories, can dominate the total late-time abundance. The viable parameter space for dark-photon dark matter is thus widened. Furthermore, in the tachyonic case, the production is dominated by a single helicity mode, leading to a population of chiral dark photons that can lead to potential parity-violating observational signatures. We further explore the dependence of the production on the reheating history, and find that information about reheating is encoded in the number density spectrum.
Related
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BibTeX
@misc{jenks2026resonant,
title = {{Resonant Gravitational Production of Chiral Dark Photons}},
author = {Leah Jenks and Marc Kamionkowski and Edward W. Kolb},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.22423},
eprint = {2609.22423},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.22423},
}
RIS
TY - UNPB
TI - Resonant Gravitational Production of Chiral Dark Photons
AU - Leah Jenks
AU - Marc Kamionkowski
AU - Edward W. Kolb
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.22423
UR - https://arxiv.org/abs/2609.22423
AB - Vector fields with a chiral, parity-odd coupling to a pseudoscalar field are known to undergo resonant amplification. In this work, we study this phenomenon in the context of cosmological gravitational particle production during early-universe inflation. We consider a massive vector (dark photon) field with a parity-odd coupling to the inflaton. There are two regimes of production, delineated by the relative size of the coupling and the dark photon mass, arising from a tachyonic instability, and a parametric resonance, respectively. As a result of the coupling, the transverse modes, subdominant in both the minimally and nonminimally coupled theories, can dominate the total late-time abundance. The viable parameter space for dark-photon dark matter is thus widened. Furthermore, in the tachyonic case, the production is dominated by a single helicity mode, leading to a population of chiral dark photons that can lead to potential parity-violating observational signatures. We further explore the dependence of the production on the reheating history, and find that information about reheating is encoded in the number density spectrum.
ER -