# Neutrino-Assisted Early Dark Energy: Theory and Cosmology

### APA

Liang, Q. (2022). Neutrino-Assisted Early Dark Energy: Theory and Cosmology. Perimeter Institute. https://pirsa.org/22120055

### MLA

Liang, Qiuyue. Neutrino-Assisted Early Dark Energy: Theory and Cosmology. Perimeter Institute, Dec. 13, 2022, https://pirsa.org/22120055

### BibTex

@misc{ pirsa_22120055, doi = {10.48660/22120055}, url = {https://pirsa.org/22120055}, author = {Liang, Qiuyue}, keywords = {Cosmology}, language = {en}, title = {Neutrino-Assisted Early Dark Energy: Theory and Cosmology}, publisher = {Perimeter Institute}, year = {2022}, month = {dec}, note = {PIRSA:22120055 see, \url{https://pirsa.org}} }

Qiuyue Liang University of Pennsylvania

## Abstract

The tension between measurements of the Hubble constant obtained at different redshifts may provide a hint of new physics active in the relatively early universe, around the epoch of matter- radiation equality. A leading paradigm to resolve the tension is a period of early dark energy, in which a scalar field contributes a subdominant part of the energy budget of the universe at this time. This scenario faces significant fine-tuning problems which can be ameliorated by a non- trivial coupling of the scalar to the standard model neutrinos. These become non-relativistic close to the time of matter-radiation equality, resulting in an energy injection into the scalar that kick- starts the early dark energy phase, explaining its coincidence with this seemingly unrelated epoch. We present a minimal version of this neutrino-assisted early dark energy model, and perform a detailed analysis of its predictions and theoretical constraints. We consider both particle physics constraints — that the model constitute a well-behaved effective field theory for which the quantum corrections are under control, so that the relevant predictions are within its regime of validity — and the constraints provided by requiring a consistent cosmological evolution from early through to late times. Our work paves the way for testing this scenario using cosmological data sets.

Zoom link: https://pitp.zoom.us/j/95613703701?pwd=amlmNUdXdXFuQitFVk8xTnNwcDlMUT09