standard model

Standard Model, in physics: see elementary particles.

---

standard model

In physics, the combination of two theories of particle physics into a single framework to describe all interactions of subatomic particles except those due to gravity (see gravitation). The two theories, the electroweak theory and the theory of quantum chromodynamics, describe the interactions between particles in terms of the exchange of intermediary particles. The model has proved highly accurate in predicting certain interactions, but it does not explain all aspects of subatomic particles. For example, it cannot say how many particles there should be or what their masses are. The search goes on for a more complete theory, and in particular a unified field theory describing the strong, weak, and electromagnetic forces.

---

standard model [′stan·dərd ′mäd·əl]

(particle physics)

The modern theory of the interactions of elementary particles, comprising the Weinberg-Salam theory and quantum chromodynamics.

---

Standard model

The theory that explains the three major interactions of elementary particle physics—the strong interaction responsible for nuclear forces, the weak interaction responsible for radioactive decay, and the electromagnetic interaction—in terms of a common physical picture. The model for this picture is quantum electrodynamics, the fundamental theory underlying electromagnetism. In that theory, electrons, viewed as structureless elementary constituents of matter, interact with photons, structureless elementary particles of light. The standard model extends quantum electrodynamics to explain all three interactions of subnuclear physics in terms of similar basic constituents. See Electron, Electroweak interaction, Elementary particle, Light, Photon, Quantum chromodynamics, Quantum electrodynamics, Strong nuclear interactions, Weak nuclear interactions