R-ATPHY-37

Norrie recommends this website.

• Mass displayed represents rest mass. Convert to Joules, then divide by $c^2$, resulting in a conventional mass.

• Fermions: building blocks of matter. These are the 6 quarks and the 6 leptons

  • Conventional matter: Usually just the 1st generation of fermions. i.e. the first column of the fermion table (up, down, electron, electron neutrino)

• Gauge bosons: Exchange particles which mediate forces

  • Higgs boson: Responsible for presence of mass in particles. For some reason that we don't care about :)

• Antimatter: all fermions have an anti-particle equivalent, i.e. opposite values. If a matter particle and anti-matter particle collide they annihilate, releasing energy.

Norrie also recommends hyperphysics!!!

Fundamental (elementary) particles

These properties are important to memorise for test:

Fermion properties

• ½ integer spin - this is a quantum property, not them actually spinning.
• Follow Pauli exclusion principle
  • Two fermions with equal quantum properties cannot occupy the same space at the same time.
  • For example, for electrons in the same orbital in chemistry, we draw $\uparrow \downarrow$, because one of the electrons must have a different spin to the other, else the Pauli exclusion principle is broken!!!
• Build up matter

Quarks

• Use strong interactions, exist in pairs or threes!
• Are in generation. As we go to heavier, higher generations, they are more likely to only have existed at the very beginning, i.e. are very rare as of now

Leptons

• Do not use strong interactions, exist independently, i.e. they just be flying around by themselves 😢

Quark generations

1st Generation

• Up (Quark)
• Down (Quark)
• Electron (Lepton)¹
• Electron neutrino (Lepton)

2nd Generation

• Charm (Quark)
• Strange (Quark)
• Muon (Lepton)
• Muon neutrino (Lepton)

3rd Generation

• Top (Quark)

• Bottom (Quark)

• Tau (Lepton)

• Tau neutrino (Lepton)

Antimatter

We notate antimatter, by putting a line on top of it, with the exception of an electron/position! For example, anti-up is $\bar{u}$, anti-charm is $\bar{c}$.

The antiparticle of an electron is a positron. But p is for proton. So:

$$\begin{align} \text{Electrons: } e^- \\ \text{Positrons: } e^+ \end{align} $$

Hadrons!

Quarks join together to produce hadrons, due to the strong force (mediated by gluons) holding them together.

Hadrons are thus any combination of quarks There are 2 common hadrons:

• Baryons (3 quarks)(fermions cause ½ integer spin!)
• Mesons (2 quarks)
  • Specifically, baryons are a quark and anti-quark pair. Doesn't have to be the same flavour.

Please note that mesons are bosons, NOT fermions. This is because they have an interger spin, which fits the definition of a boson.

Baryons

• Examples of baryons are protons and neutrons (where have I seen this before)

Quark	Charge
$u$	$+\frac{2}{3}$
$d$	$-\frac{1}{3}$

Hence,

$$\begin{align} \text{Protons (+1): } uud\implies \frac{2}{3}+\frac{2}{3}+ -\frac{1}{3}=+1 \ \checkmark \\ \text{Neutron (0): } udd \implies \frac{2}{3}+ -\frac{1}{3} + - \frac{1}{3}=0 \ \checkmark \end{align} $$

Bosons

• Integer spin
• Do not follow Pauli exclusion principle

Photon - No mass - Electromagnetic force Gluons - No mass - Strong force W&Z bosons - Mass - Weak force Graviton² (?????) - ??? - Gravity, if we could figure out if it exists...

Higgs boson - Mass - Mediates mass. Note that it has 0 spin. LHC - Massive particle - High energy The Higgs boson accounts for the mass in all other particles and solves a bunch of random issues.

Footnotes

1. Note that we notate the leptons as such: $e, \mu, \tau, \upsilon_{e},\upsilon_{\mu},\upsilon_{\tau}$. ↩

2. Note that the graviton is theoretical. ↩

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