Exchange particles
Virtual particles that mediate fundamental forces between matter particles. In quantum field theory, forces are transmitted by the exchange of virtual particles: photons for electromagnetism, W and Z bosons for weak interactions, gluons for strong interactions, and gravitons for gravity (theoretically). These particles are called virtual because they exist only briefly, below the threshold for direct detection.
Real World
At CERN's Large Hadron Collider, physicists confirmed the existence of W and Z bosons by smashing protons together at energies high enough to produce these exchange particles as real, detectable objects.
Exam Focus
Match each force to its exchange particle in a table — electromagnetic/photon, weak/W and Z, strong/gluon — as recall questions test all three.
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