Introduction to feynman diagrams

A short Introduction to Feynman Diagrams

1 Kinetic terms A quantum field theory is defined by a Lagrangian. The first step is to define the fields. such that they represent particles. That means that there should be no terms with only one field present and all vacuum expectation values should have been subtracted The kinetic terms, those containing exactly two fields, are assumed to be diagonalized. This means that all terms with two ...

Feynman diagrams versus Fermi-gas Feynman emulator

superstring Feynman diagrams

The multi-loop amplitudes for the closed, oriented superstring are represented by finite dimensional integrals of explicit functions calculated through the super-Schottky group parameters and interaction vertex coordinates on the supermanifold. The integration region is proposed to be consistent with the group of the local symmetries of the amplitude and with the unitarity equations. It is show...

0 From Finite Sets to Feynman Diagrams

‘Categorification’ is the process of replacing equations by isomorphisms. We describe some of the ways a thoroughgoing emphasis on categorification can simplify and unify mathematics. We begin with elementary arithmetic, where the category of finite sets serves as a categorified version of the set of natural numbers, with disjoint union and Cartesian product playing the role of addition and mul...

How to Define Generalized Feynman Diagrams?

Generalized Feynman diagrams have become the central notion of quantum TGD and one might even say that space-time surfaces can be identified as generalized Feynman diagrams. The challenge is to assign a precise mathematical content for this notion, show their mathematical existence, and develop a machinery for calculating them. Zero energy ontology has led to a dramatic progress in the understa...