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Abstract |
The interference between the atmospheric and solar neutrino oscillation subamplitudes is said to be responsible for CP violation (CPV) in neutrino appearance channels. More precisely, CPV is generated by the interference between the parts of the neutrino oscillation amplitude that are CP even and CP odd: even or odd when the neutrino mixing matrix is replaced with its complex conjugate. This is the CPV interference term, as it gives a contribution to the oscillation probability, the square of the amplitude, which is opposite in sign for neutrinos and antineutrinos and is unique. For this interference to be nonzero, at least two subamplitudes are required. There are, however, other interference terms, which are even under the above exchange, and these are the CP conserving (CPC) interference terms. In this paper, we explore in detail these CPC interference terms and show that they cannot be uniquely defined, as one can move pieces of the amplitude from the atmospheric subamplitude to the solar subamplitude and vice versa. This freedom allows one to move the CPC interference terms around, but does not let you eliminate them completely. We also show that there is a reasonable definition of the atmospheric and solar subamplitudes for the appearance channels such that in neutrino disappearance probability there is no atmospheric-solar CPC interference term. However, with this choice, there is a CPC interference term within the atmospheric sector. |
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