# Data-driven solutions to the Hubble tension - VIRTUAL

### APA

Lee, N. (2024). Data-driven solutions to the Hubble tension - VIRTUAL. Perimeter Institute. https://pirsa.org/24010095

### MLA

Lee, Nanoom. Data-driven solutions to the Hubble tension - VIRTUAL. Perimeter Institute, Jan. 30, 2024, https://pirsa.org/24010095

### BibTex

@misc{ pirsa_PIRSA:24010095, doi = {10.48660/24010095}, url = {https://pirsa.org/24010095}, author = {Lee, Nanoom}, keywords = {Cosmology}, language = {en}, title = {Data-driven solutions to the Hubble tension - VIRTUAL}, publisher = {Perimeter Institute}, year = {2024}, month = {jan}, note = {PIRSA:24010095 see, \url{https://pirsa.org}} }

Nanoom Lee New York University (NYU)

## Abstract

While the standard $\Lambda$CDM model provides an astonishing fit to cosmological data, there is a 4-6 $\sigma$ tension in the Hubble constant, $H_0$, between the value inferred from early-Universe observables, Planck CMB anisotropy spectra, and the value determined by local measurements from SH0ES collaboration using Type 1a supernovae calibrated with Cepheid variables. As an effort to solve this tension, we develop a method of searching for data-driven solutions to the Hubble tension given cosmological dataset, based on the standard Fisher bias formalism. Taking as proof of principle the case of a time-varying electron mass, and focusing first on Planck CMB data, we demonstrate a modified recombination can solve the Hubble tension and lower $S_8$ to better match weak lensing measurements. Once baryonic acoustic oscillation and uncalibrated supernovae data are included, it is not possible to fully solve the tension with perturbative modifications to recombination. The method we develop in this work can be a useful tool to search for many other possible extensions to the $\Lambda$CDM model, and is expected to inspire a model-building effort from the cosmology and particle physics community.

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