Thermal Leptogenesis in Brane World Cosmology

Show simple item record Okada, Nobuchika 2019-05-21T20:08:27Z 2019-05-21T20:08:27Z 2006-03-10
dc.description.abstract The thermal leptogenesis in brane world cosmology is studied. In brane world cosmology, the expansion law is modified from the four-dimensional standard cosmological one at high temperature regime in the early universe. As a result, the well-known upper bound on the lightest light neutrino mass induced by the condition for the out-of-equilibrium decay of the lightest heavy neutrino, m̃₁≲10⁻³  eV, can be moderated to be m̃₁≲10⁻³  eV × (M₁/Tₜ)² in the case of Tₜ≤M₁ with the lightest heavy neutrino mass (M₁) and the “transition temperature” (Tₜ), at which the modified expansion law in brane world cosmology is smoothly connecting with the standard one. This implies that the degenerate mass spectrum of the light neutrinos can be consistent with the thermal leptogenesis scenario. Furthermore, as recently pointed out, the gravitino problem in supersymmetric case can be solved if the transition temperature is low enough Tₜ≲10⁶⁻⁷  GeV. Therefore, even in the supersymmetric case, thermal leptogenesis scenario can be successfully realized in brane world cosmology. en_US
dc.format.mimetype application/pdf en_US
dc.language English en_US
dc.subject Particle-theory and field-theory models of the early Universe (including cosmic pancakes, cosmic strings, chaotic phenomena, inflationary universe, etc.) en_US
dc.subject Gravity in more than four dimensions, Kaluza-Klein theory, unified field theories; alternative theories of gravity en_US
dc.subject Neutrino mass and mixing en_US
dc.title Thermal Leptogenesis in Brane World Cosmology en_US
dc.type text en_US

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