https://doi.org/10.1140/epjc/s10052-024-12937-w
Regular Article – Theoretical Physics
Primordial gravitational waves assisted by cosmological scalar perturbations
1
Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, People’s Republic of China
2
University of Chinese Academy of Sciences, 100049, Beijing, People’s Republic of China
Received:
21
September
2023
Accepted:
21
May
2024
Published online:
4
June
2024
Primordial gravitational waves are a crucial prediction of inflation theory, and their detection through their imprints on the cosmic microwave background is actively being pursued. However, these attempts have not yet been successful. In this paper, we propose a novel approach to detect primordial gravitational waves by searching for a signal of second-order tensor perturbations. These perturbations were produced due to nonlinear couplings between the linear tensor and scalar perturbations in the early universe. We anticipate a blue-tilted tensor spectral index, and suggest that the tensor-to-scalar ratio can potentially be measured with high precision using a detector network composed of the ground-based Einstein Telescope and the space-borne LISA project on a decade timescale.
© The Author(s) 2024
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