Speaker
Kyohei Mukaida
Description
Equal-time expectation values, rather than asymptotic scattering amplitudes, are the natural observables in many time-dependent quantum systems. In this talk, I will present cutting rules for such in-in correlators in the Schwinger–Keldysh formalism, which reorganize perturbative contributions in a way that makes their causal structure transparent. We will then discuss cosmological correlators and cosmological-collider signals as a concrete example.