Generating PBHs and small-scale GWs in two-field models of inflation
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Abstract
Primordial black holes (PBHs) generated by gravitational collapse of large\nprimordial overdensities can be a fraction of the observed dark matter. In this\npaper, we introduce a mechanism to produce a large peak in the primordial power\nspectrum (PPS) in two-field inflationary models characterized by two stages of\ninflation based on a large non-canonical kinetic coupling. This mechanism is\ngeneric to several two-field inflationary models, due to a temporary tachyonic\ninstability of the isocurvature perturbations at the transition between the two\nstages of inflation. We numerically compute the primordial perturbations from\nlargest scales to the small scales corresponding to that of PBHs using an\nextension of BINGO (BI-spectra and Non-Gaussianity Operator). Moreover we\nnumerically compute the stochastic background of gravitational waves (SBGW)\nproduced by second order scalar perturbations within frequencies ranging from\nnano-Hz to KHz that covers the observational scales corresponding to Pulsar\nTiming Arrays, Square Kilometer Array to that of Einstein telescope. We discuss\nthe prospect of its detection by these proposed and upcoming gravitational\nwaves experiments.\n