Van der Waerden notation
In theoretical physics, Van der Waerden notation refers to the usage of two-component spinors (Weyl spinors) in four spacetime dimensions. This is standard in twistor theory and supersymmetry. It is named after Bartel Leendert van der Waerden. Dotted indices. Spinors with lower undotted indices have a left-handed chirality, and are called chiral indices. Spinors with raised dotted indices, plus an overbar on the symbol (not index), are right-handed, and called anti-chiral indices. Without the indices, i.e. "index free notation", an overbar is retained on right-handed spinor, since ambiguity arises between chirality  when no index is indicated. Hatted indices. Indices which have hats are called Dirac indices, and are the set of dotted and undotted, or chiral and anti-chiral, indices. For example, if then a spinor in the chiral basis is represented as where In this notation the Dirac adjoint (also called the Dirac conjugate) is