Primordial Monopoles, Black Holes and Gravitational Waves

We show how topologically stable superheavy magnetic monopoles and primordialblack holes can be generated at observable levels by the waterfall field inhybrid inflation models based on grand unified theories. In SU(5) ×U(1)_χ grand unification, the monopole mass is of order 4 × 10^17GeV, and it carries a single unit (2 π /e) of Dirac magnetic charge as wellas screened color magnetic charge. The monopole density is partially diluted toan observable value, and accompanied with the production of primordial blackholes with mass of order 10^17-10^19 g which may make up the entiredark matter in the universe. The tensor to scalar ratio r is predicted to beof order 10^-5 - 10^-4 which should be testable in the next generationof CMB experiments such as CMB-S4 and LiteBIRD. The gravitational wave spectrumgenerated during the waterfall transition is also presented.