Скачать или смотреть Talk by Dr. Enrico Pajer, DAMTP, CMS, University of Cambridge, UK at QASTM seminar

Title:"Cosmology from the Boundary: Building a Boostless Bootstrap"

Abstract: Cosmological surveys are believed to measure the future value of quantum correlators in a theory of gravity around quasi de Sitter spacetime. The goal of this talk is to develop a cosmological bootstrap, namely understand how general physical principles such as unitarity, locality and symmetries are encoded in these observables without a reference to the unobservable time evolution that generates them.
I'll show that in single-clock inflation, the only correlators of curvature perturbations that are fully de Sitter isometric are those of the free theory. This provides a strong motivation to develop a "Boostless" Bootstrap that does not assume invariance under de Sitter boosts (generally broken during inflation). I'll show how all tree-level bispectra for a massless scalar and graviton follow from a set of simple boundary Bootstrap Rules.
To move beyond the bispectrum, I'll derive a Cosmological Optical Theorem, which expresses the consequences of unitary time evolution in the bulk for the boundary spatial correlations dictated by the wavefunction of the universe. This provides a very powerful relation between higher- and lower-order diagrams. As an example, I'll show who to compute the (exchange) trispectrum from a given bispectrum.

Speaker: Dr. Enrico Pajer
Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, UK.

Date and Time: 12 th November 2020, (3 :00 PM to 5:30 PM Berlin time) 7.30 PM to 10 PM Indian time.

Zoominar link: https://mpi-aei.zoom.us/j/97623339163

Contact: Dr. Sayantan Choudhury ([email protected])