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Three antiquarks of different anticolors, giving an antibaryon with baryon number −1. The baryon number was defined long before the quark model was established, so rather than changing the definitions, particle physicists simply gave quarks one third the baryon number. Nowadays it might be more accurate to speak of the conservation of quark ...
Mesons named with the letter "f" are scalar mesons (as opposed to a pseudo-scalar meson), and mesons named with the letter "a" are axial-vector mesons (as opposed to an ordinary vector meson) a.k.a. an isoscalar vector meson, while the letters "b" and "h" refer to axial-vector mesons with positive parity, negative C-parity, and quantum numbers I G of 1 + and 0 − respectively.
Because quarks have a spin 1 / 2 , the difference in quark number between mesons and baryons results in conventional two-quark mesons being bosons, whereas baryons are fermions. Each type of meson has a corresponding antiparticle (antimeson) in which quarks are replaced by their corresponding antiquarks and vice versa.
The best known baryons are protons and neutrons, which make up 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 , known as an antibaryon, in which quarks are replaced by their corresponding antiquarks.
Mesons are made of a valence quark–antiquark pair (thus have a baryon number of 0), while baryons are made of three quarks (thus have a baryon number of 1). This article discusses the quark model for the up, down, and strange flavors of quark (which form an approximate flavor SU(3) symmetry). There are generalizations to larger number of flavors.
QCD predicts that quarks and antiquarks bind into particles called mesons. Another type of hadron is called a baryon, that is made of three quarks. There is good experimental evidence for both mesons and baryons. Potentially QCD also has bound states of just gluons called glueballs.
This gives new eigenvectors, which we can call K 1 which is the difference of the two states of opposite strangeness, and K 2, which is the sum. The two are eigenstates of CP with opposite eigenvalues; K 1 has CP = +1, and K 2 has CP = −1 Since the two-pion final state also has CP = +1, only the K 1 can decay this way.
An X boson would have the following two decay modes: [1]: 442 X + → u L + u R X + → e + L + d R. where the two decay products in each process have opposite chirality, u is an up quark, d is a down antiquark, and e + is a positron. A Y boson would have the following three decay modes: [1]: 442 Y + → e + L + u R Y