In physics, force carrier is a particle whose creation, annihilation, and exchange gives rise to one of the forces of the universe.  It is believed that the force carriers, like the leptons and quarks, are fundamental particles with no substructure. The term force carrier is synonymous with field particle, messenger particle, and force mediator.
1. Ford, Kenneth W. (2004). The Quantum World, (pg. 46). Cambridge, Mass.: Harvard University Press.