Talk by Professor Subodh Patil,  Universiteit Leiden, The Netherlands at QASTM seminar
Channel: Sayantan Choudhury
Date: 2021-01-25

Title: What's left to learn from primordial observables (effectively speaking)?

Abstract: All cosmological observables to date are consistent with scale free, adiabatic, Gaussian initial conditions, with evidence of weak logarithmic running. We infer this from observations of Cosmic Microwave Background (CMB) anisotropies, Large Scale Structure (LSS) surveys, and various other tracers of the underlying matter distribution at late times. These initial conditions are consistent with a particular symmetry breaking pattern in the early universe widely attributed (but not necessarily due) to a phase of early universe inflation but without offering any further clues as to the physical nature of the responsible degree of freedom, let alone its embedding in some theory that goes beyond the Standard Model of particle physics. In this talk, I will provide a review of what we know from current observations (and how we know it), and discuss near term and planned observations and the possibilities they present for understanding primordial physics from an effective field theory (EFT) perspective. These near term observations include measurements of CMB spectral distortions, future LSS surveys, gravitational wave astronomy and potentially 21 cm tomography. Along the way I will review the EFT tools used in potentially extracting evidence for new physics and characteristic scales from the observables in question, making pit stops to highlight certain subtleties regarding the separation of scales on time dependent backgrounds and strong coupling in the presence of gravity. Time permitting, I will present a result that shortcuts the computation of quantum corrections to cosmological observables, drawing a line under a debate in the literature on the nature of loops during inflation, and apply the result to how one can bound the number of hidden sectors in the Universe.

Speaker: Professor Subodh Patil, Instituut-Lorentz for Theoretical Physics
Universiteit Leiden Niels Bohrweg, CA Leiden, The Netherlands.

Date and Time: 25 th January, 6.30 PM to 9 PM (Indian Time) and 2 PM to 4.30 PM (Berlin Time).

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

Contact: Dr. Sayantan Choudhury (sayantan.choudhury@niser.ac.in)