An Effective Framework for Quantum Fluctuations with Applications to Cosmology

Abstract

Quantum fluctuations can be thought of as new degrees-of-freedom (DoFs) on top of the original classical system. In this talk, the speaker will introduce a canonical effective framework that encodes quantum fluctuations as additional independent DoFs within an enlarged phase space. At the lowest order, these additional DoFs help make up the textbook effective potentials in an effective action, which can be understood as assuming a fixed evolution for fluctuations. When fluctuations evolve freely, however, they can dynamically capture effects of real-time quantum backreaction and even quantum tunneling.

The speaker will demonstrate this effective framework in the context of inflation on two levels. First, on the background level, the speaker will illustrate how quantum backreaction can dynamically modulate the inflationary potential, potentially altering predictions even in the simplest models. Second, on the perturbative level, the speaker will provide an example showing how this framework reproduces superhorizon results for both the 2-point and 3-point correlation functions, as derived via the “in-in” formalism. He will conclude by highlighting the key advantages of this effective framework and proposing directions for future applications.
 

About the Speaker

Dr. DING Ding obtained his BSc from Lanzhou University in 2016. He then went on to complete his doctorate in Pennsylvania State University in 2022. He has been a post-doc at Fudan University since 2022.
 

About the Program

For more information, please refer to the program website at http://iasprogram.ust.hk/particle_theory.

For Attendees' Attention

• Seating is on a first come, first served basis.