Phenomenological consequences of phase transitions occurred during inflation

          @misc{ pirsa_PIRSA:25080033,
            doi = {10.48660/25080033},
            url = {https://pirsa.org/25080033},
            author = {An, Haipeng},
            keywords = {Cosmology, Particle Physics, Strong Gravity},
            language = {en},
            title = {Phenomenological consequences of phase transitions occurred during inflation},
            publisher = {Perimeter Institute},
            year = {2025},
            month = {aug},
            note = {PIRSA:25080033 see, \url{https://pirsa.org}}
          }
          

Abstract

In slow-roll inflationary models, the inflaton can undergo excursions on the order of the Planck scale, leading to significant changes in the properties of fields coupled to the inflaton, referred to as spectator fields. These changes may result in transitions between weakly and strongly interacting regimes, or even alterations in mass squared within the spectator field sector during inflation. Such dynamics can induce phase transitions, which have profound implications for the early Universe. In this talk, I will explore the phenomenological consequences of these phase transitions, focusing on the production of gravitational waves, curvature perturbations, non-Gaussianities, dark matter, and baryon number. I will also demonstrate how gravitational waves generated by scalar perturbations induced by phase transitions may potentially explain the alleged gravitational wave signals observed in recent pulsar timing array studies.