A Feynman diagram is a graphical representation of the interactions between particles in quantum field theory. It is used to calculate the probability of a specific scattering process or interaction between particles.
To evaluate a Feynman diagram without external fermion lines, you first need to assign mathematical expressions to each line and vertex in the diagram. These expressions represent the propagator for the particle and the interaction between particles, respectively. Then, you use Feynman rules to calculate the amplitude of the diagram, which is then used to determine the probability of the scattering process.
Feynman diagrams provide a visual representation of complex mathematical calculations in QFT, making it easier to understand and interpret the results. They also allow for the calculation of higher-order corrections to scattering processes, which would be difficult to do using traditional methods.
Yes, Feynman diagrams can be used for all types of particle interactions, including electromagnetic, weak, and strong interactions. However, the specific Feynman rules for each type of interaction may vary.
Evaluating Feynman diagrams in QFT is essential for understanding the behavior of particles and their interactions. It is used in a wide range of applications, including particle physics experiments, particle accelerator design, and theoretical calculations of particle interactions in various physical systems.