Abstract

The use of geometrical quantities and geometrical methods in the calculation and interpretation of physical systems have been very successful. Among others it has been shown how non-relativistic spin one half and massless relativistic spin one half with the corresponding Pauli matrices can be phrased geometrically. An analogous formulation for massive and relativistic spin one half was however missing. By the use of geometrical angular coordinates we construct a concrete realization of relativistic and massive spin one half. A Lagrange formulation is found, equations of motion are derived, and Lorentz invariance is discussed.