Description
The interaction of neutrino magnetic moments with the solar magnetic field can give rise to the phenomenon of spin-flavour precesion. For Majorana neutrinos, the effect of spin-flavour precession together with flavour oscillations would manifest itself as a small, yet potentially detectable, flux of electron antineutrinos. The non-observation of such a flux can be used to constrain the product of the solar magnetic field and the neutrino magnetic moments. Taking, as a starting point, a simple analytical expression for the electron antineutrino appearence probability derived in the three neutrino picture, we check its validity by comparing it with full numerical calculations and apply it to revisit the existing limits on the product of the neutrino transition magnetic moment $\mu_{12}$ and the magnetic field at the neutrino production point inside the Sun. The outlined procedure can also be applied to future solar antineutrino searches.
