📚 Quarks, Leptons and Exchange Particles | 夸克、轻子与交换粒子
The Standard Model of particle physics organises all known elementary particles and describes three of the four fundamental forces. Quarks and leptons are the fundamental fermions that build matter, while exchange particles — the gauge bosons — carry the forces between them. A deep grasp of their properties is a core requirement in IB Physics, especially in Topic 7.
粒子物理学的标准模型对所有已知的基本粒子进行了分类，并描述了四种基本相互作用中的三种。夸克和轻子是构成物质的基本费米子，而交换粒子（规范玻色子）则在它们之间传递相互作用。深刻理解它们的性质是IB物理（尤其是Topic 7）的核心要求。
1. The Standard Model Overview | 标准模型概览
The Standard Model divides particles into fermions (matter particles with half-integer spin) and bosons (force mediators with integer spin). All stable matter around us is built from first-generation fermions: up and down quarks, electrons and electron neutrinos. The model also accounts for two heavier generations and the antiparticles of every fermion.
标准模型将粒子分为费米子（具有半整数自旋的物质粒子）和玻色子（具有整数自旋的力的媒介粒子）。我们身边所有稳定物质都由第一代费米子构成：上夸克、下夸克、电子以及电子中微子。该模型也涵盖了两个更重的代以及每种费米子的反粒子。
The forces are described by the exchange of gauge bosons: the photon for electromagnetism, W and Z bosons for the weak force, and gluons for the strong force. Gravity, mediated by the hypothetical graviton, is not yet integrated into the Standard Model.
基本力通过交换规范玻色子来描述：光子传递电磁力，W⁺、W⁻和Z⁰玻色子传递弱力，胶子传递强力。由假想的引力子传递的引力尚未被纳入标准模型。
2. Quarks: The Building Blocks of Hadrons | 夸克：强子的基本单元
Quarks are spin-½ fermions with fractional electric charges. They feel all four fundamental forces and are the only particles that experience the strong force. There are six flavours of quarks, grouped into three generations.
夸克是自旋为½的费米子，带分数电荷。它们能感受全部四种基本力，并且是唯一能感受强力的粒子。夸克共有六种“味”，分成三代。
| Flavour | Symbol | Charge (e) | Baryon number | Strangeness | Charm | Bottomness | Topness |
|---|---|---|---|---|---|---|---|
| up | u | +⅔ | +⅓ | 0 | 0 | 0 | 0 |
| down | d | -⅓ | +⅓ | 0 | 0 | 0 | 0 |
| strange | s | -⅓ | +⅓ | -1 | 0 | 0 | 0 |
| charm | c | +⅔ | +⅓ | 0 | +1 | 0 | 0 |
| bottom | b | -⅓ | +⅓ | 0 | 0 | -1 | 0 |
| top | t | +⅔ | +⅓ | 0 | 0 | 0 | +1 |
夸克的六种味及其量子数如上表所示。每一味夸克的重子数都是+⅓，反夸克的重子数为-⅓。奇异数S、粲数C、底数B’和顶数T在强相互作用与电磁相互作用中守恒，但在弱相互作用中不守恒。
3. Properties of Quarks | 夸克的性质详解
Quarks carry a baryon number B = +⅓. Antibaryons are made of three antiquarks, each with B = -⅓, giving a total baryon number of -1. The electric charge of a quark is either +⅔e or -⅓e. Because qu
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