Neutrinos in Cosmology

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Author: A.D. Dolgov

Published in: E-libraryme Publish

ISBN: 1-5925-7003-8

File Type: pdf

File Size:  3 MB

Language: English

Description

Cosmological implications of neutrinos are reviewed. The following subjects are discussed at a different level of scrutiny: cosmological limits on neutrino mass, neutrinos and primordial nucleosynthesis, cosmological constraintson unstable neutrinos, lepton asymmetry of the universe, impact of neutrinos on cosmic microwave radiation, neutrinos and the large scale structure of the universe, neutrino oscillations in the early universe, baryo/lepto-genesis and neutrinos, neutrinos and high energy cosmic rays, and briefly some more exotic subjects: neutrino balls, mirror neutrinos, and neutrinos from large extra dimensions. Neutrinos in Cosmology The existence of neutrino was first proposed by Pauli in 1930 as an attempt to explain the continuous energy spectrum observed in beta-decay under the assumption of energy conservation. Pauli himself did not consider his solution to be a very probable one, though today such observation would be considered unambiguous proof of the existence of a new particle. That particle was named “neutrino” in 1933, by Fermi. A good, though brief description of historical events leading to νdiscovery can be found in ref. The method of neutrino detection was suggested by Pontecorvo. To this end he proposed the chlorine-argon reaction and discussed the possibility of registering solar neutrinos. This very difficult experiment was performed by Davies et al in 1968, and marked the discovery neutrinos from the sky (solar neutrinos). The experimental discovery of neutrino was carried out by Reines and Cowan in 1956, a quarter of a century after the existence of that particle was predicted.

In 1943 Sakata and Inou ̈e suggested that there might be more than one species of neutrino. Pontecorvo in 1959 made a similar conjecture that neutrinos emitted in beta-decay and in muon decay might be different. This hypothesis was confirmed in 1962 by Danby et al, who found that neutrinos produced in muon decays could create in secondary interactions only muons but not electrons.