Baryon number

In particle physics, the baryon number is a strictly conserved additive quantum number of a system. It is defined as In particle physics, the baryon number is a strictly conserved additive quantum number of a system. It is defined as where nq is the number of quarks, and nq is the number of antiquarks. Baryons (three quarks) have a baryon number of +1, mesons (one quark, one antiquark) have a baryon number of 0, and antibaryons (three antiquarks) have a baryon number of −1. Exotic hadrons like pentaquarks (four quarks, one antiquark) and tetraquarks (two quarks, two antiquarks) are also classified as baryons and mesons depending on their baryon number. Quarks carry not only electric charge, but also charges such as color charge and weak isospin. Because of a phenomenon known as color confinement, a hadron cannot have a net color charge; that is, the total color charge of a particle has to be zero ('white'). A quark can have one of three 'colors', dubbed 'red', 'green', and 'blue'; while an antiquark may beeither anti-red, anti-green or anti-blue.