Gravitational waves from preheating in Gauss–Bonnet inflation K. El Bourakadi, M. Ferricha-Alami, H. Filali, Z. Sakhi and M. Bennai Eur. Phys. J. C, 81 12 (2021) 1144 Published online: 30 December 2021 DOI: 10.1140/epjc/s10052-021-09946-4