IMSc Webinar

Neutrinos in Cosmology; google meet link: meet.google.com/tvk-itpg-fws

Shouvik Roy Choudhury

IITB, Mumbai

Neutrinos are massless in the standard model of particle physics. However, neutrino oscillation experiments have established that at least 2 of the 3 neutrino mass eigenstates should be massive. Neutrino oscillation experiments are only sensitive to the mass-squared splittings, and not the absolute masses,thus keeping the mass of the lightest neutrino unbounded. At the same time, the neutrino mass hierarchy remains undetermined from oscillations data. Cosmological data, on the other hand, is sensitive to the sum of these neutrino masses, and the tightest bounds on the sum of the masses come from cosmology. A solution to the neutrino mass hierarchy problem might also come from cosmology. In this seminar, I shall discuss the current status of the measurement of neutrino mass and mass hierarchy from cosmology. Also, in the recent past, strong non-standard neutrino self-interactions with a heavy mediator were shown to be a potential solution to the Hubble tension, which is currently one of the biggest problems in cosmology. Here I shall present our recent analysis results with the latest CMB data from Planck 2018 where we do not find any reconciliation of the Hubble tension with a cosmological model that includes non-standard neutrino self-interactions.