Hybrid ?-attractors, primordial black holes and gravitational wave backgrounds

We investigate the two-stage inflation regime in the theory of hybrid cosmological alpha-attractors. The spectrum of inflationary perturbations is compatible with the latest Planck/BICEP/Keck Array results, thanks to the attractor properties of the model. However, at smaller scales, it may have a very high peak of controllable width and position, leading to a copious production of primordial black holes (PBH) and generation of a stochastic background of gravitational waves (SGWB).