Calculating Feynman Diagrams in Time Domain

Calculating Transition Amplitudes from Feynman Diagrams

When one thinks of quantum field theory, one’s mind is undoubtedly drawn to Feynman diagrams. The näıve view these diagrams as merely a concise and standardized way of describing collisions and processes. Feynman diagrams, however, encode a great deal of information, for each one corresponds exactly to the probability amplitude of the transition it describes. In other words, it is easily possib...

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...

Feynman Diagrams in Quantum Mechanics

We explain the use of Feynman diagrams to do perturbation theory in quantum mechanics. Feynman diagrams are a valuable tool for organizing and understanding calculations. We first work several examples for the 1-dimensional harmonic oscillator, and then proceed to justify our calculations.

Generating 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...