While the Standard Model has been remarkably successful in explaining fundamental particles and interactions, it does not fully account for several neutrino-related mysteries such as the origin of neutrino mass, potential sterile neutrino states, and the matter-antimatter asymmetry in the universe.
Many beyond the SM theories propose the existence of new particles, such as heavy right-handed neutrinos, which could explain the small observed masses of the known neutrino species through the so-called seesaw mechanism.
Likewise, precision measurements in neutrino experiments aim to test CP violation in the neutrino sector, which could be crucial for understanding why our universe is dominated by matter rather than a balanced mix of matter and antimatter.