[HET seminar] Neutrinos in Cosmology

by Miguel Escudero

Thursday 7 Oct 2021, 11:00 → 12:00 US/Eastern

https://bnl.zoomgov.com/j/1612154637?pwd=Z2E5RWhqRXBkMnExQzc3eVBTWTg3UT09

Neutrinos are a key (although implicit) ingredient of the standard cosmological model, LambdaCDM. Firstly, neutrinos directly participate in Big Bang Nucleonsynthesis, and secondly, they represent 40% of the energy density of the Universe after electron positron annihilation up to almost matter radiation equality. The latter fact makes neutrinos a necessary ingridient to understand the very precise observations of the Cosmic Microwave Background.

In this seminar, I will review the cosmological implications of neutrinos. I will explain how current cosmological observations can be used to constrain their masses and their abundances. In particular, I will discuss various cosmological settings where the typically very stringent constraint on their masses can be substantially relaxed. In this context, I will comment on the possibilities to directly detect the Cosmic Neutrino Background in the laboratory in future experiments such as PTOLEMY. Finally, I will review the role neutrinos can play with regards to the outstanding Hubble tension. In particular, I will show that pseudo-Goldstone bosons (majorons) interacting with neutrinos right before recombination represent a well motivated possibility to ameliorate the Hubble tension.

Escudero_BNL.pdf