Feynmandiagrammeja

Feynmandiagrammeja are graphical tools used in quantum field theory to represent terms in perturbative expansions of particle interactions. They encode the possible interaction processes and provide a practical method to compute scattering amplitudes and decay rates.

Historically, Feynman diagram techniques were introduced by Richard Feynman in the mid-20th century as part of quantum electrodynamics and were later extended to the Standard Model. The diagrams offer a visual shorthand for mathematical expressions that describe how particles interact through fundamental forces.

A diagram consists of lines and vertices. External lines represent incoming and outgoing particles, while internal lines denote virtual particles propagating between interaction points. Different line styles indicate particle types: solid lines with arrows for fermions, wavy lines for gauge bosons like photons, and dashed lines for scalar particles. Vertices correspond to fundamental interaction terms in the theory, and momentum conservation is enforced at each vertex.

Feynman rules translate a diagram into a specific integral or algebraic expression. Each vertex contributes a coupling constant, each line a propagator, and each loop introduces an integration over internal momenta. Tree-level diagrams have no loops and give leading-order results; loop diagrams include quantum corrections and often require renormalization to handle divergences.

Feynmandiagrammeja are widely used in quantum electrodynamics, quantum chromodynamics, and electroweak theory to predict cross sections, decay rates, and other observables. They are a standard tool in theoretical and experimental particle physics, valuable for organizing complex calculations and interpreting experimental data.