Leptogenesis

Abstract: This form of notation is connected with the quark concept; we ascribe to the/?, n, and Л quarks n c = + I, and to antiquarks, и,. = — 1. The theory proposes that under laboratory conditions processes involving violation of п в and и д play a negligible role, but they were very important during the earlier stage of the expansion of the universe. We assume that the universe is neutral with respect to the conserved charges (lepton, electric, and combined), but С asymmetrical during the given instant of its development (the positive lepton charge is concentrated in the electrons and the negative lepton charge in the excess of antineutrinos over the neutrinos; the positive electric charge is concentrated in the protons and the negative in the electrons; the positive combined charge is concentrated in the baryons, and the negative in the excess of fi neutrinos over/z antineutrinos). According to our hypothesis, the occurrence of С asymmetry is the consequence of violation of CP in variance in the nonstationary expansion of the hot universe during the superdense stage, as manifest in the difference between the partial probabilities of the charge-conjugate reactions. This effect has not yet been observed experimentally, but its existence is theoretically undisputed (the first concrete example, I, + and 2 _ decay, was pointed out by S. Okubo as early as 1958) and should, in our opinion, have much cosmological significance. We assume that the asymmetry has occurred in an earlier stage of the expansion, in which the particle, energy, and entropy densities, the Hubble constant, and the temperatures were of the order of unity in gravitational units (in conventional units the particle and energy densities were n~ 10

Abstract: Abstract This book is unique in the detailed, self-contained, and comprehensive treatment that it gives to the ideas and formulas that are used and tested in modern cosmological research. It divides into two parts, each of which provides enough material for a one-semester graduate course. The first part deals chiefly with the isotropic and homogeneous average universe; the second part concentrates on the departures from the average universe. Throughout the book the author presents detailed analytic calculations of cosmological phenomena, rather than just report results obtained elsewhere by numerical computation. The book is up to date, and gives detailed accounts of topics such as recombination, microwave background polarization, leptogenesis, gravitational lensing, structure formation, and multifield inflation, that are usually treated superficially if at all in treatises on cosmology. Copious references to current research literature are supplied. Appendices include a brief introduction to general relativity, and a detailed derivation of the Boltzmann equation for photons and neutrinos used in calculations of cosmological evolution. Also provided is an assortment of problems.