| | |
Summary: astro-ph/9905259 v2 21 May 1999
Neutrino-Mixing-GeneratedLeptonAsymmetryandthe
Primordial4
HeAbundance
XiangdongShi,GeorgeM.FullerandKevorkAbazajian
DepartmentofPhysics,UniversityofCalifornia,SanDiego,LaJolla,California92093-0319
January23,1999
Ithasbeenproposedthatanasymmetryintheelectronneutrinosector
maybegeneratedbyresonantactive-sterileneutrinotransformationsduring
BigBangNucleosynthesisBBN.Wecalculatethechangeintheprimordial
4HeyieldYresultingfromthisasymmetry,takingintoaccountboththetime
evolutionoftheeandedistributionfunctionandthespectraldistortions
inthese.Wecalculatethischangeintwoschemes:1aleptonasymmetry
directlygeneratedbyemixingwithalighterright-handedsterileneutrino
s;and2aleptonasymmetrygeneratedbya$sor$strans-
formationwhichissubsequentlypartiallyconvertedtoanasymmetryinthe
eesectorbyamatter-enhancedactive-activeneutrinotransformation.In
therstscheme,wendthatthepercentagechangeinYisbetween,1
and9withthesigndependingonthesignoftheasymmetry,bounded
bytheMajoranamasslimitme1eV.Inthesecondscheme,themax-
|
