BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Shota Komatsu (CERN) DTSTART:20220125T020000Z DTEND:20220125T030000Z DTSTAMP:20260423T023937Z UID:ATP2022/6 DESCRIPTION:Title: Analyticity and Unitarity for Cosmological Correlators\nby Shota Komat su (CERN) as part of Advances in Theoretical Physics 2022\n\n\nAbstract\nI will discuss the fundamentals of quantum field theory on a rigid de Sitte r space. First\, I will show that the perturbative expansion of late-time correlation functions to all orders can be equivalently generated by a non -unitary Lagrangian on a Euclidean AdS geometry. This finding simplifies d ramatically perturbative computations\, as well as allows us to establish basic properties of these correlators\, which comprise a Euclidean CFT. Se cond\, I use this to infer the analytic structure of the spectral density that captures the conformal partial wave expansion of a late-time four-poi nt function\, to derive an OPE expansion\, and to constrain the operator s pectrum. Third\, I will prove that unitarity of the de Sitter theory manif ests itself as the positivity of the spectral density. This statement does not rely on the use of Euclidean AdS Lagrangians and holds non-perturbati vely.\n LOCATION:https://researchseminars.org/talk/ATP2022/6/ END:VEVENT END:VCALENDAR