Luminous solar neutrinos II: Mass-mixing portals

Understand

Solar neutrinos can be efficiently upscattered to MeV scale heavy neutral leptons (HNLs) within the Earth's mantle.

• HNLs can then decay to electron-positron pairs leading to energy deposition inside large-volume detectors.
• In this paper we consider mass-portal upscattering of solar neutrinos to HNLs of mass 20 MeV $\geq m_N \geq 2 m_e$.
• The large volume of the Earth compensates for the long decay-length of the HNLs leading to observable rates of $N\rightarrow \nu_\alpha e^+e^-$ in large volume detectors.