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The cross sections and neutron decay more » width decrease with temperature because color-electric-charge screening reduces the self-dual-instanton density at finite temperature.
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The neutron decays via n.->.p-bar+e-bar+nu-bar with a lifetime of the order 10/sup 146/ years. e-bar+nu-bar and eleven other similar reactions are of order s x 10/sup -195/ cm/sup 2/, where s is the total center-of-momentum energy squared in GeV/sup 2/. At zero temperature the total cross sections for p+n.->. As an example we consider a simplified model involving only the proton, neutron, electron, and electron neutrino. We make a quantitative study of instanton-induced baryon- and lepton-number-violating processes in an SU(2) x U(1) electroweak gauge theory at zero and finite temperatures (in the ''dilute-instanton-gas'' approximation). We also discuss the case when baryon number U(1)B is promoted to a gauge symmetry, and discuss electroweak baryogenesis and its corresponding phenomenology. We explore the model phenomenology related to the leptophilic Z', the dark matter candidate, the Higgs boson, and the additional scalar, as well as implications for electric dipole moments.
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Weak sphalerons are then in charge of transforming the net lepton charge asymmetry into net baryon number. Dark CP violation is diffused in front of the bubble walls and creates a chiral asymmetry for χ, which in turn creates a chemical potential for the standard model leptons. The complex scalar field couples to the Higgs portal and is essential in enabling a strong first order phase transition. The lepton number is spontaneously broken at high scale and the effective theory, containing the standard model, the Z', the fermionic dark matter, and an additional complex scalar field S, violates CP in more » the dark sector. Extra fermionic degrees of freedom, including a fermionic dark matter χ, are introduced in the dark sector for anomaly cancellation. This is based on a novel electroweak baryogenesis mechanism first proposed by us in Ref. We explore the generation of the baryon asymmetry in an extension of the standard model where the lepton number is promoted to a U(1)ℓ gauge symmetry with an associated Z' gauge boson. In many models this implies that neutrinos must be so light that they cannot contribute appreciably to the mass density of the Universe. Without introducing new particles-beyond the usual quarks and leptons-it is necessary that the Universe possess a nonzero value of is the temperature at which a B - L asymmetry is produced. In some cases the electron-neutrino asymmetry is exactly specified in terms of the baryon asymmetry. In the presence of rapid fermion-number violation due to nonperturbative electroweak effects certain relations between the baryon number of the Universe and the lepton numbers of the Universe are predicted.