Parity-violating primordial gravitational waves from null energy condition violation
Abstract
We investigate the parity-violating effects in primordial gravitational waves (GWs) due to null energy condition (NEC) violation in two very early universe scenarios: bounce-inflation and intermediate NEC violation during inflation. In both scenarios, we numerically solve the power spectra of parity-violating primordial GWs generated by coupling the background field and the spectator field with the Nieh-Yan term, respectively. We find that the background field can significantly enhance parity-violating effects at scales corresponding to the maximum of the GW power spectra. In contrast, the parity-violating effects produced by the spectator show significantly weaker observability even if the coupling constant is large. Therefore, in NEC-violating scenarios, the significant observable parity-violating effects in primordial GWs primarily arise from the physics directly related to NEC violation. This result highlights the potential of primordial GWs as crucial tools for exploring NEC-violating and parity-violating physics.
Cite
@article{arxiv.2406.16549,
title = {Parity-violating primordial gravitational waves from null energy condition violation},
author = {Zi-Wei Jiang and Yong Cai and Fei Wang and Yun-Song Piao},
journal= {arXiv preprint arXiv:2406.16549},
year = {2024}
}
Comments
32 pages, match published version, reference added