Seesaw Mechanism

An elegant theoretical framework that explains the profound smallness of neutrino masses. It postulates the existence of very heavy, sterile "right-handed" neutrinos. The "seesaw" name comes from the mathematical relationship: the mass of the familiar, light neutrinos we observe is inversely proportional to the immense mass of these hypothetical heavy partners. When one goes up, the other goes down. If the heavy neutrinos are at scales a trillion times heavier than a proton, this naturally generates the tiny, observed masses for the active neutrinos. This mechanism not only solves the neutrino mass puzzle but also provides a possible pathway for generating the matter-antimatter asymmetry of the universe through a process called leptogenesis, making it a cornerstone of modern particle cosmology.