Effective Methods In Cosmology And Gravity
Open Access
- Author:
- Ding, Ding
- Graduate Program:
- Physics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 10, 2022
- Committee Members:
- Radu Roiban, Major Field Member
Ping Xu, Outside Unit & Field Member
Eugenio Bianchi, Major Field Member
Martin Bojowald, Chair & Dissertation Advisor
Nitin Samarth, Program Head/Chair - Keywords:
- Effective methods
Cosmology
Gravity
Quantum field theory - Abstract:
- In this dissertation, I summarize how canonical effective methods can be applied to describe quantum corrected gauge symmetries, non-adiabatic corrections in inflation, and backreactions that seed correlations and inhomogeneities. Special attention will be paid to the canonical structure and dynamics of quantum fluctuations (which can be interpreted as the moments of a quantum state). I will use canonical methods to highlight the role of constraints in the quantum corrected low energy effective theory of gravity; deformed covariance is shown to be a generic consequence. Reconciliation between seemingly different effective Hamiltonians is also discussed in this context. I then explore the effects of dynamical quantum fluctuations on effective potentials in inflation. I show how these fluctuations affect observables and help us characterize the quantum state, thus establishing a state-to-observable correspondence. Finally, I discuss the role of backreactions on background correlations and inhomogeneity growth. I find that distinct oscillation behaviors arise when correlations are present. Furthermore, the trickling of infrared inhomogeneities to smaller length scales is demonstrated to exist with the inclusion of non-local effects from quantum moments.