Two-component complex objects transforming under the double cover SL(2,C) of the proper Lorentz group. Required to describe half-integer-spin particles (electron, neutrino, quark); rotation by 2π returns ψ → −ψ.
Two-component complex objects transforming under the double cover SL(2,C) of the proper Lorentz group. Required to describe half-integer-spin particles (electron, neutrino, quark); rotation by 2π returns ψ → −ψ.