Yes, Feynman diagrams are still widely used in quantum electrodynamics (QED) and other quantum field theories. Feynman diagrams provide a visual and calculational tool for representing and computing particle interactions and processes in quantum field theory.
In QED, which is the quantum field theory describing the electromagnetic force and the interaction of photons with charged particles, Feynman diagrams are particularly useful for calculating scattering amplitudes and cross sections. They represent different particle interactions as lines and vertices, with each line representing a particle or antiparticle and each vertex representing an interaction between particles.
Feynman diagrams allow physicists to visualize and calculate the probabilities of various particle interactions and to determine the likelihood of specific outcomes. They provide a way to systematically organize and compute the contributions from different possible particle interactions, leading to predictions that can be compared with experimental data.
While Feynman diagrams originated in the context of quantum electrodynamics, they have also been extended and adapted for other quantum field theories, such as quantum chromodynamics (QCD) describing the strong nuclear force. Feynman diagrams remain an essential tool for theoretical physicists working in the field of quantum field theory and are widely used in calculations, theoretical studies, and the development of new theories.