Electron-Positron Collisions

Figure 18.9: Two jet events resulting from the annihilation of high energy electrons and positrons. The virtual photon decays into a quark-antiquark pair which in turn generate the oppositely pointing jets of particles.

Two jet events can also be created by the collision of high energy electrons and positrons. Figure 18.9 shows how this process is thought to work. The annihilation of the electron and positron results in a virtual photon, which in turn decays into a quark-antiquark pair. The quarks then produce the jets. These results suggest that quarks can indeed occur outside of protons, at least if they occur in quark-antiquark pairs.