https://doi.org/10.1140/epjc/s10052-021-09001-2
Regular Article – Theoretical Physics
Resonance instability of primordial gravitational waves during inflation in Chern–Simons gravity
1
Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, 410081, Changsha, Hunan, China
2
School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 310024, Hangzhou, China
3
School of Physical Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
4
Institute for Theoretical Physics and Cosmology, Zhejiang University of Technology, 310032, Hangzhou, Zhejiang, China
5
United Center for Gravitational Wave Physics (UCGWP), Zhejiang University of Technology, 310032, Hangzhou, Zhejiang, China
Received:
25
July
2020
Accepted:
23
February
2021
Published online:
1
March
2021
We investigate axion inflation where the gravitational Chern–Simons term is coupled to a periodic function of the inflaton. We find that tensor perturbations with different polarizations are amplified in different ways by the Chern–Simons coupling. Depending on the model parameters, the resonance amplification results in a parity-violating peak or a board plateau in the energy spectrum of gravitational waves, and the sharp cutoff in the infrared region constitutes a characteristic distinguishable from stochastic gravitational wave backgrounds produced by matter fields in Einstein gravity.
© The Author(s) 2021
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