Gluon

A Gluon is a subatomic particle that hold quarks together. It is at about 1.3 MeVs, versus the quark’s 200,000. They are vector bosons that mediate the strong force. Gluons "glue" quarks together, forming hadrons. The gluon has negative intrinsic parity. They have color unlike other particles. Since gluons themselves carry color charge, they participate in strong interactions. Gluons are also found in the hypothetical 5th state of matter quark-gluon plasma.

Experiments
The PLUTO detector at the DORIS collider was the first one to observe gluons. In 1979, the higher-energy PETRA collider found qq gluon bremsstrahlung.