Restrictions on B - L Symmetry Breaking Implied by a Fourth Generation Neutrino †
نویسندگان
چکیده
We point out that if the fourth generation neutrino is a Majorana fermion, then the astrophysical constraints coupled with the precision measurements of the Z-width at LEP require that the corresponding B-L symmetry is unlikely to be a spontaneously broken global symmetry. If B-L is chosen to be a local symmetry, its breaking scale should be less than a few TeV.
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