A hypothetical neutrino state with opposite chirality to observed left-handed neutrinos, possibly existing in extra dimensions.Right-handed neutrinos are hypothetical neutrino states that would interact with matter only through gravity, not through the weak nuclear force, making them extremely difficult to detect. In the Standard Model of particle physics, neutrinos are assumed to be massless and only left-handed, but the observation of neutrino oscillations implies they have mass, which requires the existence of right-handed neutrinos. These particles could be extremely heavy, explaining why they are not observed at low energies, or they could be light and sterile, interacting even more weakly than ordinary neutrinos.
The concept was introduced in the 1970s by several theorists, including Peter Minkowski, Murray Gell-Mann, Pierre Ramond, and Richard Slansky, as a natural explanation for neutrino masses via the seesaw mechanism.
In the theory of neutrino mass, right-handed neutrinos are introduced as partners to the observed left-handed ones. They can mix with left-handed neutrinos through a mass matrix, and in the seesaw mechanism, their heavy mass suppresses the mass of the left-handed neutrinos, explaining why neutrinos are so light. If right-handed neutrinos are light, they would be sterile, meaning they do not participate in weak interactions, and could only be detected through their gravitational effects or through oscillations with active neutrinos.
They are a candidate for dark matter and could explain the matter-antimatter asymmetry of the universe through leptogenesis, where their decays generate a lepton asymmetry that is converted to a baryon asymmetry.
If right-handed neutrinos are very heavy, they could have existed in the early universe and decayed, potentially creating the observed excess of matter over antimatter.


