The Eta Meson

Eta 介子

Particle 质点	Symbol 符号	Anti- particle 反粒子	Makeup 组成	Rest mass MeV/c² 静止质量 MeV/c²	S	C	B	Lifetime 寿命	Decay Modes 衰变模式
Eta Eta（专名或术语）	η⁰	Self 自身	2*	548.8	0	0	0	<10^-18	2γ, 3μ
Eta prime Eta prime（专名或术语）	η^0'	Self 自身	2*	958	0	0	0	...	π⁺π^-η

2* The neutral eta meson is considered to be a quark combination

Meson diagram

介子图

Table of mesons

介子表

中性eta介子被认为是由夸克组成的。

Index

Particle concepts

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The Rho Meson

_rho 介子

Particle 质点	Symbol 符号	Anti- particle 反粒子	Makeup 组成	Rest mass MeV/c² 静止质量 MeV/c²	S	C	B	Lifetime 寿命	Decay Modes 衰变模式
Rho Rho（专名或术语）	ρ⁺	ρ^-	ud	770	0	0	0	0.4 x10^-23	π⁺π⁰
Rho Rho（专名或术语）	ρ⁰	Self 自身	uu, dd	770	0	0	0	0.4 x10^-23	π⁺π^-
Omega 欧米伽	ω⁰	Self 自身	uu, dd	782	0	0	0	0.8 x10^-22	π⁺π^-π⁰

The rho meson has the same quark composition as the pion and can be considered to be an excited state of the pion. The fact that its mass is five and one half times the mass of the pion illustrates the difficulties of assigning mass to the quarks. Hadron masses depend upon the dynamics inside the particle, and not just upon the quarks contained. The quark modeling of the pion and rho classifies the pion as a pseudoscalar meson with zero angular momentum. The quarks have spin 1/2 and the spins are "paired" or anti-aligned. In the rho meson, a vector meson, the angular momentum is j=1, indicating parallel spins. Under the influence of the strong color force, the state with spins aligned has a higher energy which shows up as a larger mass energy. The analogy to the higher energy of aligned spins in a magnetic field (Zeeman effect) is instructive, but this difference in energy associated with the color force is enormous.

ρ介子的夸克组成与π介子相同，可以被视为π介子的激发态。其质量是π介子质量的五点五倍，这说明将夸克的质量赋予数值存在困难。强子的质量取决于粒子内部的动力学，而不仅仅是所含的夸克。π介子和ρ介子的夸克模型将π介子分类为自旋为零、角动量为零的赝标量介子。夸克的自旋为1/2，且自旋是“配对”或反向对齐的。在ρ介子中，作为矢量介子，其角动量为j=1，表明自旋是平行的。在强色力作用下，自旋对齐的状态具有更高的能量，这表现为更大的质量能量。与磁场所致的自旋对齐状态的更高能量（塞曼效应）的类比是有启发性的，但与色力相关的能量差异却非常巨大。

Georgi comments "There is good reason to believe that most of the mass of the quark that we 'see' in the mass of the proton or the rho is a dynamical effect of quark confinement, that the u and d quarks in the underlying QCD theory actually have masses much smaller than 1/3 the mass of the proton."

Georgi指出："有充分理由相信，我们看到的质子或ρ介子中的夸克质量，大部分是夸克禁闭的动力学效应，即在基本的QCD理论中，u和d夸克的实际质量远小于质子质量的1/3。"

The omega meson is grouped here with the rho mesons because of similar mass and the same constituent quarks.

这里的omega介子与rho介子归为一类，因为它们具有相似的质量和相同的构成夸克。

Meson diagram

介子图

Table of mesons

介子表

Index

Particle concepts

Reference
Georgi

粒子概念索引参考Georgi

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The Phi Meson

Phi 介子

Particle 质点	Symbol 符号	Anti- particle 反粒子	Makeup 组成	Rest mass MeV/c² 静止质量 MeV/c²	S	C	B	Lifetime 寿命	Decay Modes 衰变模式
Phi 菲	φ	Self 自身	ss	1020	0	0	0	20 x10^-23	K⁺K^-,K⁰K⁰

Meson diagram

介子图

Table of mesons

介子表

Index

Particle concepts

索引粒子概念

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