The atomic nucleus is a bound state of protons and neutrons so called nucleons. The A4 collaboration is investigating the structure of these nucleons.
The BaBar experiment is an international collaboration of more than 500 physicists and engineers studying the subatomic world at energies of approximately ten times the rest mass of a proton ~10 GeV. Its design was motivated by the investigation of CP violation. BaBar is located at the SLAC National Accelerator Laboratory, which is operated by Stanford University for the Department of Energy in California.