Neutrina

Neutrina is a hypothetical elementary particle proposed in certain extensions of the Standard Model of particle physics. The term is used in some theoretical contexts as a neutral, weakly interacting fermion analogous to the neutrino, but with distinct properties that set it apart from known neutrino species. The exact characteristics of a neutrina vary by model, but typical descriptions assume a spin-1/2 fermion with neutral electric charge and a mass scale that may be very light or significantly heavier, depending on the theory. The particle may be Dirac or Majorana in nature and could mix with standard neutrinos or belong to a separate family of states.

Interactions and detection: neutrina is expected to interact primarily via the weak force, leading to very small interaction cross-sections. Some models allow additional interactions through new gauge forces or portal couplings to dark sectors. Because of weak interactions and potentially small mass, neutrinas would be extremely difficult to detect directly and would typically produce missing energy and momentum signatures in detectors.

Origin and role: in some theories neutrinas are introduced to address questions such as the origin of neutrino masses, the matter–antimatter asymmetry, or dark matter. They may arise as heavy neutral leptons in the early universe or as low-mass states in extended neutrino sectors.

Status: there is currently no experimental confirmation of neutrinas. Constraints come from collider experiments, precision electroweak measurements, cosmology, and neutrino experiments; future experiments and observations could probe relevant mass ranges and mixings.

See also: neutrino, sterile neutrino, heavy neutral lepton, beyond the Standard Model.