|Tuesday 26 January 2021|
|Events for day: Tuesday 27 October 2020|
| 14:00 - 15:00 Weekly Seminar|
The Cosmological Optical Theorem
In the scattering amplitude program, one directly bootstraps the S-matrix by implementing analyticity, locality, and unitarity without resorting to the language of Lagrangians and introducing gauge redundancies. Recently much effort has been dedicated to developing similar methods in cosmology. The primary goal here is to discover a set of basic rules implied by locality, analyticity, and unitarity, that uniquely pinpoint consistent boundary correlation functions without invoking the time evolution in the bulk. In this work, we set forward new ideas in the arena of "cosmological bootstrap" by deriving the consequences ...
16:30 - 18:00 Mathematics Colloquium
Transfer Operators, Atomic Decomposition and Besov Spaces
We use the method of atomic decomposition to study the action of transfer operators associated to piecewise expanding maps. It turns out that these transfer operators are quasi-compact even when the associated potential, the dynamics and the underlying phase space have very low regularity. In particular it is often possible to obtain exponential decay of correlations, the Central Limit Theorem and almost sure invariance principle for fairly general observables, including unbounded ones. Indeed the class of observables for which we obtain such results often coincides with certain Besov spaces. Joint work with Alexander Arbieto (UFRJ-Brazil). ...