What is feynman slash?

Feynman slash is a mathematical notation used in the field of theoretical physics, particularly in quantum field theory. It is denoted by a slash through a symbol, typically a gamma matrix or a spinor. The notation is used to represent a mathematical operation called the Dirac slash, which involves taking the product of a four-vector with a gamma matrix or spinor. This operation is used to express the Lorentz-invariant products of fermion fields in scattering amplitudes. The Feynman slash notation was introduced and popularized by the Nobel laureate physicist Richard Feynman, who used it extensively in his famous lectures on quantum mechanics and quantum field theory.