Baryons

Thursday, March 12, 2009

Baryons are composite particles made of up three quarks. baryons and mesons are part of the larger particle family which comprises all particles made up of quarks; the hadrons. The term baryon is derived from the Greek barys, which means "heavy", because at the time of their naming it was believed that baryons were characterized by having greater masses than other particles.

As baryons are composed of quarks, they take part in the strong interaction. The most famous baryons are the protons and neutrons which constitute most of the mass of the visible matter in the universe, whereas electrons, the other major component of atoms, are leptons. Each baryon has a corresponding antiparticle where quarks are replaced by their corresponding antiquarks. For example, a proton is made of two up quarks and one down quark. Its corresponding antiparticle, the antiproton, is made of two up antiquarks and one down antiquark.

Baryons are strongly interacting fermions, which means that they experience the strong nuclear force and are described by Fermi-Dirac statistics, which apply to all particles obeying the Pauli exclusion principle. The bosons, on the other hand, do not obey the exclusion principle.

Baryons, together with mesons, are hadrons. That is to say they are particles composed of quarks. Quarks have baryon numbers of B = 1/3 and antiquarks have baryon number of B = -1/3. The term "baryon" usually refers to triquarks—baryons made of three quarks (B = 1/3 + 1/3 + 1/3 = 1).