Allison Pinto (HU Berlin)

Title: Gauge Invariant Cosmological Perturbation Theory and Homotopy Transfer

Abstract:

In cosmology, one of the complications of describing perturbations around an expanding background is gauge freedom. One approach, introduced by Bardeen in 1980, is to formulate the perturbation theory in terms of gauge invariant variables. I will show how Bardeen’s procedure is equivalent to homotopy transfer in the framework of L-infinity algebras. Moreover, I will discuss how this new interpretation can be useful in systematizing the extension of gauge invariant perturbation theory to all orders in perturbations.