A technique for generating Feynman diagrams
نویسندگان
چکیده
We present a simple technique that allows to generate Feynman diagrams for vector models with interactions of order 2n and similar models (Gross-Neveu, Thirring model) using a bootstrap equation that uses only the free field value of the energy as an input. The method allows to find the diagrams to, in principle, arbitrarily high order and applies to both energy and correlation functions. It automatically generates the correct symmetry factor (as a function of the number of components of the field) and the correct sign for any diagram in the case of fermion loops. We briefly discuss the possibility of treating QED as a Thirring model with non-local interaction. Research assistant NFWO, e-mail: [email protected] Senior research associate NFWO, e-mail: [email protected]
منابع مشابه
Feynman Diagrams and the Kdv Hierarchy
The generating functional of the intersection numbers of the stable cohomology classes on moduli spaces of curves satisfy the string equation and a KdV hierarchy. We give a proof of this classical Kontsevich-Witten result completely in terms of Feynman diagrams.
متن کاملCombinatorial Physics, Normal Order and Model Feynman Graphs
Abstract. The general normal ordering problem for boson strings is a combinatorial problem. In this talk we restrict ourselves to single-mode boson monomials. This problem leads to elegant generalisations of well-known combinatorial numbers, such as Bell and Stirling numbers. We explicitly give the generating functions for some classes of these numbers. Finally we show that a graphical represen...
متن کاملGenerating and Calculating One-loop Feynman Diagrams with FeynArts, FormCalc, and LoopTools
A set of programs is presented for automatically generating and calculating Feynman diagrams. Diagrams are generated with FeynArts, then algebraically simplified using a combination of Mathematica and FORM implemented in the package FormCalc, and finally evaluated numerically using the LoopTools package. FormCalc works either in dimensional regularization or in constrained differential renormal...
متن کاملPerturbation theory via Feynman diagrams in classical mechanics
In this paper we show how Feynman diagrams, which are used as a tool to implement perturbation theory in quantum field theory, can be very useful also in classical mechanics, provided we introduce also at the classical level concepts like path integrals and generating functionals.
متن کاملGenerating functionals for harmonic expectation values of paths with fixed end points: Feynman diagrams for nonpolynomial interactions.
We introduce a general class of generating functionals for the calculation of quantum-mechanical expectation values of arbitrary functionals of fluctuating paths with fixed end points in configuration or momentum space. The generating functionals are calculated explicitly for the harmonic oscillator with time-dependent frequency, and used to derive a smearing formula for correlation functions o...
متن کامل