Xiao-Gang He, Xue-Qian Li, Bruce H. J. McKellar, Yue Zhang
Published 2004-12-24, updated 2005-05-18Version 4
We study the Berry phase in neutrino oscillations for both Dirac and Majorana neutrinos. In order to have a Berry phase, the neutrino oscillations must occur in a varying medium, the neutrino-background interactions must depend on at least two independent densities, and also there must be CP violation if the neutrino interactions with matter are mediated only by the standard model W and Z boson exchanges which implies that there must be at least three generations of neutrinos. The CP violating Majorana phases do not play a role in generating a Berry phase. We show that a natural way to satisfy the conditions for the generation of a Berry phase is to have sterile neutrinos with active-sterile neutrino mixing, in which case at least two active and one sterile neutrinos are required. If there are additional new CP violating flavor changing interactions, it is also possible to have a non-zero Berry phase with just two generations.
Comments: RevTex 16 pages, no figures, new discussions about sterile neutrino added,typos corrected and errors in references corrected
Journal: Phys.Rev. D72 (2005) 053012
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