Primordial black holes in SB SUSY Gauss-Bonnet inflation

Abstract: Here, we explore the formation of primordial black holes (PBHs) within a scalar field inflationary model coupled to the Gauss-Bonnet (GB) term, incorporating the low-scale spontaneously broken supersymmetric (SB SUSY) potential. The coupling function amplifies the curvature perturbations, consequently leading to the formation of PBHs and detectable secondary gravitational waves (GWs). Through the adjustment of the model parameters, the inflaton can be decelerated during an ultra-slow-roll (USR) phase, thereby augmenting curvature perturbations. Beside the observational constraints, the swampland criteria are investigated. Our computations forecast the formation of PBHs with masses around ${\cal O}(10)M_{\odot}$, aligning with the observational data of LIGO-Virgo, and PBHs with masses ${\cal O}(10^{-6})M_{\odot}$ as potential explanation for the ultrashort-timescale microlensing events recorded in the OGLE data. Additionally, our proposed mechanism can generate PBHs with masses around ${\cal O}(10^{-13})M_{\odot}$, constituting roughly 99$\%$ of the dark matter. The density parameters of the produced GWs ($\Omega_{\rm GW_0}$) intersect with the sensitivity curves of GW detectors. Two cases of our model fall within the nano-Hz frequency regime. One of them satisfies the power-law scaling as $\Omega_{\rm{GW}}(f) \sim f^{5-\gamma}$, with the $\gamma = 3.51$, which is consistent with the data of NANOGrav 15-year.