Light sterile neutrinos, spin flavour precession and the solar neutrino experiments

Understand

We generalize to three active flavours a previous two flavour model for the resonant spin flavour conversion of solar neutrinos to sterile ones, a mechanism which is added to the well known LMA one.

• The transition magnetic moments from the muon and tau neutrinos to the sterile play the dominant role in fixing the amount of active flavour suppression.
• We also show, through numerical integration of the evolution equations, that the data from all solar neutrino experiments except Borexino exhibit a clear preference for a sizable magnetic field either in the convection zone or in the core and radiation zone.
• This is possibly related to the fact that the data from the first set are average ones taken during a period of mostly intense solar activity, whereas in contrast Borexino data were taken during a period of quiet sun.