素ハ研セミナー: Yvonne Y.Y. Wong (New South Wales Univ.)
- 発表者: Yvonne Y.Y. Wong (New South Wales Univ.)
- 日時: 10/26 （水）. 13:30- (JST) @E002 and オンライン (Teams)
- 題目: Neutrinos in Cosmology: Calculations of the neutrino-to-photon ratio and the spatial neutrino density distribution
- 概要: Standard hot Big Bang cosmology predicts the existence of a cosmic neutrino background (CnuB), analogous to its better known cousin, the cosmic microwave background (CMB). With a predicted number density of about 100 neutrinos+antineutrinos per cubic centre per family today, the shear abundance of these CnuB neutrinos ensures that they have a nontrivial impact on the many stages of the evolution of the universe. An immediate corollary is that cosmological observations such as the CMB anisotropies and the large-scale matter distribution are sensitive to the CnuB, and can in turn be used to constrain its properties.
In this talk, I will report on a recent precision theoretical calculation of the neutrino-to-photon energy density ratio—commonly referred to as the “effective number of thermalised neutrino species” Neff—within the Standard Model of particle physics, as well as discuss some recent works in the computation of massive neutrino effects on the spatial distribution of matter and the clustering of the CnuB itself.