Messenger Particles
The messengers of the strong interaction are called gluons because they "glue"
the quarks together into particles like protons and neutrons and in turn
glue protons and neutrons together into atomic nuclei. Photons are the
messengers of the electromagnetic interaction and particles called W and Z
carry the weak interaction. Gravitons are believed to carry gravity, but
they have so far not been found.
One of the things that determines the range of an interaction is the mass
of the messenger particles...
...heavier messengers have a shorter range.
Particle Physics Education CD-ROM ©2001 CERN