In her talk, Prof. Yuko Urakawa discussed the generalized deltaN formalism of cosmological perturbations, which dramatically facilitates a computation of the primordial density perturbation and the primordial gravitational waves. In particular, she addressed a violation of the cosmological principle, namely a violation of the global isotropy in the Universe. A major implication of her study is that measuring the PGWs provides a powerful tool to explore a violation of the global isotropy. Such effects can potentially be searchable by the future space-based CMB polarization mission LiteBIRD.

Reported by Ryo Namba