Neutrinoantineutrino

Neutrinoantineutrino refers to the pair formed by a neutrino and its antiparticle, the antineutrino. In the Standard Model, each lepton flavor has a neutrino and a corresponding antineutrino: electron neutrino and electron antineutrino, muon neutrino and muon antineutrino, tau neutrino and tau antineutrino. Neutrinos are neutral, very light fermions that interact predominantly through the weak force and gravity. They are produced in a variety of processes, including beta decay, nuclear reactions in stars, and particle decays.

A key distinction is between neutrinos and antineutrinos under lepton number conservation. For Dirac neutrinos, the neutrino and antineutrino are distinct particles with lepton numbers +1 and −1, respectively. If neutrinos are Majorana particles, they would be their own antiparticles, rendering the distinction between neutrino and antineutrino dependent on the chosen description; experimentally distinguishing these possibilities is an active area of research, notably in the search for neutrinoless double beta decay.

Interactions of neutrinos and antineutrinos differ in charged-current processes. A neutrino of flavor l interacts via a W+ exchange to produce the corresponding charged lepton l−, e.g., νl + n → l− + p. An antineutrino interacts via a W− exchange to produce the corresponding antiparticle lepton l+, e.g., ν̄l + p → l+ + n. Both types interact with the Z boson in neutral-current processes.

Neutrino–antineutrino pairs can annihilate at high energies into Z bosons or W boson pairs, and they participate in flavor oscillations. The study of these pairs informs questions about neutrino masses, mixing, and the possible Majorana nature of neutrinos, with implications for cosmology and particle physics.