KATRIN Experiment Refines Neutrino Mass Upper Limit

The KATRIN experiment has established the most precise upper limit yet for the mass of neutrinos, setting it at less than 0.45 electron volts, which is less than one-millionth the mass of an electron. This finding refines the previously estimated upper mass limit by nearly half and challenges the Standard Model's assumption that neutrinos are massless. Neutrinos, known for their elusive nature and abundance in the universe, have a mass that influences cosmic structures and galaxy formation. The KATRIN collaboration, involving over a hundred scientists, achieved this result by analyzing the beta decay of tritium, observing the energy distribution between electrons and electron antineutrinos. This advancement not only narrows the possible mass range for neutrinos but also pushes the boundaries of particle physics beyond the Standard Model. The experiment is set to continue until 2025, aiming to further constrain the neutrino mass limit.