Feynman slash notation

In the study of Dirac fields in quantum field theory, Richard Feynman invented the convenient Feynman slash notation (less commonly known as the Dirac slash notation). If A is a covariant vector (i.e., a 1-form), In the study of Dirac fields in quantum field theory, Richard Feynman invented the convenient Feynman slash notation (less commonly known as the Dirac slash notation). If A is a covariant vector (i.e., a 1-form), using the Einstein summation notation where γ are the gamma matrices. Using the anticommutators of the gamma matrices, one can show that for any a μ {displaystyle a_{mu }} and b μ {displaystyle b_{mu }} , where I 4 {displaystyle I_{4}} is the identity matrix in four dimensions.