Gravitational waves and primordial black holes from inflation with Gauss–Bonnet correction

In this paper, we discuss the generation of gravitational waves (GWs) from the de Sitter fixed points in the T-model inflation with Gauss–Bonnet coupling and investigate the possibility to induce double peaks of GW spectrum by consider multiple domain wall crossings processes in moduli space. For certain parameter choices, the resulting GW spectrum has two peaks with frequencies in around Formula: see text and Formula: see text, which can be observed by the worldwide pulsar timing array (PTA) and the space GW detectors simultaneously. Additionally, the reentry of the power spectrum peaks into the horizon leads to the collapse into primordial black holes (PBHs). We calculate the abundance of PBHs using the method of peak theory and found that the masses is in the range of Formula: see text and around Formula: see text, which constitute significant components of the current dark matter.