Composite Fermions and Bosons

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© CERN.

The protons that came together in the LHC collision shown on the left are composite fermions made of three spin-1/2 quarks. Most protons we encounter in our daily lives behave as single composite fermions, no questions asked. However, collisions at the LHC and other particle accelerators are energetic enough that the proton's internal structure cannot be ignored. At the opposite end of the energy scale are the electrons in superconductors, such as the one pictured on the right, which must be cooled well below room temperature. We normally think of electrons as individual spin-1/2 particles, but in a superconductor the electrons are paired up into bosons. It is these bosonic pairs that determine the electrical properties of the superconductor. (Unit: 6)