Probing neutrino magnetic moment and unparticle interactions with Borexino

Understand

We discuss the limits on the neutrino magnetic moment and hypothetical interactions with a hidden unparticle sector, coming from the first neutrino data release of the Borexino experiment.

• The observed spectrum in Borexino depends weakly on the solar model used in the analysis, since most of the signal comes from the mono-energetic 7Be neutrinos.
• This fact allows us to calibrate the nu-e scattering cross section through the spectral shape.
• In this way, we have derived a limit on the magnetic moment for the neutrinos coming from the Sun (in which a nu_mu and nu_tau component is present): mu_nu<8.4E-11 mu_B (90%CL) which is comparable with those obtained from low energy reactor experiments.