Bottom quark

Third generation quarks with charge − 1 ⁄ 3 e

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Bottom quark Yes with charge − the third generation of 1 ⁄ 3 e quark , also known as Mequark 。

Chinese name: Bottom quark

Foreign name: Bottom quark
Discovery: Fermilab

catalog

one brief introduction
two Hadron with bottom quark

three Quark model
four States other than quark model

five see

brief introduction

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Although quantum chromodynamics describes each kind of quark in a similar way, because the bottom quark has a large Naked mass (about 4.2GeV/ c two , slightly more than proton Four times the mass), and CKM matrix Elements of V ub And V cb The value of is very small, so the bottom quark has a unique label. As an experiment, a method called Bottom sticker Its trace can be easily identified by the technology of. because CP damage Three generations of quarks are involved, so the particles suitable for studying CP violation are those containing bottom quarks meson 。 BaBar experiment 、 Belle experiment And LHCb Experiments of this kind are being carried out.^[1]

Hadron with bottom quark

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Main entry: Baryon list

Here are some of the hadron ：

B meson Contains a bottom quark (or Antibottom quark ）With a Upper quark or Lower quark 。
Bc meson contains a bottom quark and Charm quark 。
The Bs meson contains a bottom quark and a Odd quark 。
There are many kinds Bottom quarkonium State, such as Pion 、 Large Hadron Collider First discovered particle χb(3P) 。 They are all particles formed by a bottom quark and an anti bottom quark.
Bottom quark containing baryon It has been observed that they are named like odd baryons.^[1]

Quark model

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stay Particle physics On, Quark model (English: Quark Model) quark The category of hadron classification scheme, and the valence quark is the quark and anti quark in the hadron, they are hadrons Quantum number The source of. Quark is“ SU (3) taste symmetry ”Or Octet This classification scheme successfully grouped a large number of lighter hadrons discovered in the 1950s and 1960s. It was experimentally confirmed in the late 1960s, and is still a correct and effective classification method. In 1964, the quark model was Murray Gelman and George Zweig Independent proposal (see also). Today, the quark model has been Standard model The standard model refers to the established Strong interaction and Weak current interaction Quantum field theory.

Hadrons are not "basic" and can be regarded as the bound states of "valence quarks" and their anti quarks, which are the source of hadron quantum numbers. These quantum numbers are labels to identify hadrons and can be divided into two types. A kind of Poincare symmetry

However, J, P and C represent Total angular momentum 、 Parity and Charge conjugation symmetry 。^[2]

States other than quark model

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Although the quark model can be derived from the theory of quantum chromodynamics, the structure of hadrons is much more complex than the model can allow. Completeness of all hadrons quantum mechanics wave function Must include virtual quark pairs and virtual Gluon Yes, at the same time, multiple kinds of mixing should be allowed. There may be hadrons outside the quark model. Such particles include Rubber ball (only containing valence gluons), mixed particles (containing valence gluons and quarks) and“ exotic hadron ”(including Tetraquark state and Pentaquark state ）。^[2]

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Quark model

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