PIRSA:20060023

Light Hidden Sectors and the Hubble Tension

APA

Blinov, N. (2020). Light Hidden Sectors and the Hubble Tension. Perimeter Institute. https://pirsa.org/20060023

MLA

Blinov, Nikita. Light Hidden Sectors and the Hubble Tension. Perimeter Institute, Jun. 09, 2020, https://pirsa.org/20060023

BibTex

          @misc{ pirsa_PIRSA:20060023,
            doi = {10.48660/20060023},
            url = {https://pirsa.org/20060023},
            author = {Blinov, Nikita},
            keywords = {Particle Physics},
            language = {en},
            title = {Light Hidden Sectors and the Hubble Tension},
            publisher = {Perimeter Institute},
            year = {2020},
            month = {jun},
            note = {PIRSA:20060023 see, \url{https://pirsa.org}}
          }
          

Nikita Blinov Fermi National Accelerator Laboratory (Fermilab)

Collection
Talk Type Scientific Series

Abstract

The inference of the present expansion rate from the Cosmic Microwave Background and other early-time probes (assuming standard
cosmology) is in significant tension with several direct measurements of the same quantity. If this discrepancy is not due to unresolved systematics, it could provide strong evidence for physics beyond the standard models of particle physics and cosmology. I will describe a few simple models that attempt to alleviate this Hubble tension. All of these scenarios containĀ additional energy density of new light particles at early times with interactions that modify the background cosmology and evolution of density perturbations in the early universe. First, I will motivate the existence of a decaying component of dark matter with a significant free-streaming length as a means of addressing this tension. Then I will consider models with self-interacting neutrino or dark radiation components. I will show that such scenarios face stringent cosmological and laboratory constraints. As a result, in these examples, the tension can be alleviated but not eliminated altogether.