Protons are made of more fundamental particles called quarks held together by particles, called gluons, that transmit the strong nuclear force.
The objects which carry the color force between quarks and hence glue them into hadrons are called gluons.
The radiated gluons themselves are not directly observed but are instead detected via their hadronic decay products.
At a critical point the potential stored in the color field manifests itself as spontaneously emitted gluons, which then split into quark-antiquark pairs.
Strong interaction The interaction responsible for binding quarks, antiquarks, and gluons to make hadrons.