Force carrier

In particle physics, the quantum field theory called the Standard Model describes the strong, weak and electromagnetic fundamental forces. In such theories, each type of interaction has a characteristic set of force carrier particles associated with quantum excitation[?] of the force field[?] related to that interaction.

The carrier particles either appear in intermediate stages or are produced during all particle processes involving that type of interaction. Forces between particles can be described in terms of static force fields and exchanges of force carrier particles between the affected particles.

All force carriers particules are bosons:

• Gluons are the carrier particles of strong interactions.
• Photons are the carrier particles of electromagnetic interactions.
• W and Z bosons are the carrier particles of weak interactions.

The name for the carrier particle of gravitational interactions is the graviton. The status of this particle is still tentative, because the theory is incomplete and there has been no good experimental evidence that they exist. Gravitons are not considered to be a part of the Standard Model.

In the Standard Model a fifth interaction type is needed to account for the masses of all particles, the hypothetical Higgs field carried by Higgs bosons.