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The evolution of the electro-weak phase transition, including reheating due to the release of latent heat in shock w a v es, is calculated for various values of as yet unknown parameters of electro-weak theory such as latent heat and bubble wall surface tension. We show that baryon production, which occurs in the vicinity of the bubble walls of the phase transition, can be a sensitive function of bubble wall velocity, and this velocity dependence is important to include in the calculation of the baryon density of the universe. There is a sensitive v elocity dependence for all mechanisms of baryon production, depending on the magnitude of velocity of the bubble wall, and we examine in particular an inverse velocity dependence on baryon production, which is predicted by the charge transport mechanism of baryon production. For this mechanism we nd both an enhancement of baryon production and the generation of inhomogeneities during the electro-weak phase transition. We calculate the magnitude of the baryon enhancement, which can be as large as a few orders of magnitude, depending on the parameters of the theory, and we calculate the size and amplitude of the inhomogeneities generated. We determine that the inhomogeneities generated in a thermally nucleated electro-weak phase transition are to small to survive di usive processes and e ect the nucleosynthesis epoch. We also examine the possibility that a phase transition nucleated by other means, such a s b y the presence of cosmic strings, may produce inhomogeneities that could e ect nucleosynthesis.

In the standard Big Bang cosmology the canonical value for the ratio of relic neutrinos to CMB photons is 9/11. Within the framework of the Standard Model of particle physics there are small corrections, in sum about 1%, due to slight heating of neutrinos by electron/positron annihilations and finite-temperature QED effects. We show that this leads to changes in the predicted cosmic microwave background (CMB) anisotropies that might be detected by future satellite experiments. NASA's MAP and ESA's PLANCK should be able to test the canonical prediction to a precision of 1% or better and could confirm these corrections.Comment: 8 pages + 3 figure

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We show that once a black hole surpasses some critical temperature T crit , the emitted Hawking radiation interacts with itself and forms a nearly thermal photosphere. Using QED, we show that the dominant interactions are bremsstrahlung and electronphoton pair production, and we estimate T crit ∼ m e /α 5/2 , which when calculated more precisely is found to be T crit ≈45 GeV. The formation of the photosphere is purely a particle physics effect, and not a general relativistic effect, since the the photosphere forms roughly α −4 Schwarzschild radii away from the black hole. The temperature T of the photosphere decreases with distance from the black hole, and the outer surface is determined by the constraint T ∼ m e (for the QED case), since this is the point at which electrons and positrons annihilate, and the remaining photons free stream to infinity. Observational consequences are discussed, and it is found that, although the QED photosphere will not affect the Page-Hawking limits on primordial black holes, which is most important for 100MeV black holes, the inclusion of QCD interactions may significantly effect this limit, since for QCD we estimate T crit ∼ Λ QCD . The photosphere greatly reduces possibility of observing individual black holes with temperatures greater than T crit , since the high energy particles emitted from the black hole are processed through the photosphere to a lower energy, where the gamma ray background is much higher. The temperature of the plasma in the photosphere can be extremely high, and this offers interesting possibilities for processes such as symmetry restoration.