Solar neutrinos and leptonic spin forces

• Saeed Ansarifard (School of Physics, IPM)

In this talk, I quantify the effects of light spin-zero particles with pseudoscalar couplings to leptons and scalar couplings to nucleons on the evolution of solar neutrinos. I show in this scenario the matter potential sourced by the nucleons in the Sun’s matter gives rise to spin precession of the relativistic neutrino ensemble. For Dirac neutrinos, the spin-flavour precession results in active-sterile oscillations, while for Majorana neutrinos it results in left-handed neutrino to right-handed antineutrino oscillations. In both cases, this leads to distortions in the solar neutrino spectrum which we use to derive constraints on the allowed values of the mediator mass and couplings via a global analysis of the solar neutrino data. In addition for Majorana neutrinos, spin-flavour precession results into a potentially observable flux of solar electron antineutrinos at the Earth which we quantify and constrain with the existing bounds from Borexino and KamLAND.