Quark model

The quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. These quantum numbers are labels identifying the hadrons, and are of two kinds. One set comes from the Poincare symmetry — JPC(m) (where J is the angular momentum, P, the intrinsic parity, and C the charge conjugation parity). The remainder are flavour quantum numbers such as the isospin, I. When three flavours of quarks are taken into account, the quark model is also known as the eightfold way, after the meson octet of the figure below (with an allusion to the eightfold way of buddhism).

Related Topics:
Hadron - Quark - Quantum number - Poincare symmetry - Angular momentum - Intrinsic parity - Charge conjugation - Flavour - Isospin - Eightfold way - Eightfold way - Buddhism

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The quark model uses the standard assignment of quantum numbers to quarks — spin 1/2, baryon number 1/3, electric charge 2/3 for the u quark and -1/3 for the d and s. Antiquarks have the opposite quantum numbers. Mesons are made of a valence quark-antiquark pair, and hence have baryon number zero. Hadrons are made of three quarks and hence have unit baryon number. This article discusses the quark model for SU(3) flavour, which involves the u, d and s quarks. There are generalizations to larger number of flavours.

Related Topics:
Spin - Baryon number - Electric charge - Meson - Hadron - SU(3)

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