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Naturally Large Cosmological Neutrino Asymmetries in the MSSM

John McDonald

hep-pharXiv:hep-ph/9908300

Abstract

A large neutrino asymmetry is an interesting possibility for cosmology, which can have significant observable consequences for nucleosynthesis and the cosmic microwave background. However, although it is a possibility, there is no obvious reason to expect the neutrino asymmetry to be observably large. Here we note that if the baryon asymmetry originates via the Affleck-Dine mechanism along a d=4 flat direction of the MSSM scalar potential and if the lepton asymmetry originates via Affleck-Dine leptogenesis along a d=6 direction, corresponding to the lowest dimension directions conserving R-parity, then the ratio nL/nB is naturally in the range 108-109. As a result, a potentially observable neutrino asymmetry is correlated with a baryon asymmetry of the order of 10-10.

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