# Physics - Standard Model

> Source: https://ollybritton.com/notes/a-level/physics/topics/standard-model/ · Updated: 2022-01-31 · Tags: school, physics, year-2, particle-phyiscs

## Flashcards
### 2022-01-31
##### What are the four fundamental forces??
1. Strong nuclear force
2. Weak nuclear force
3. Electromagnetic force
4. Gravitational force

##### In what context does the strong nuclear force show up??
Holding nucleons together.

##### When does the electromagnetic force act??
When two charged objects interact.

##### In what context does the weak nuclear force show up??
Beta decay.

##### When does the gravitational force show??
When any particles have mass.

##### What is the relative strength of the strong nuclear force??
$$
1
$$

##### What is the relative strength of the electromagnetic force??
$$
10^{-3}
$$

##### What is the relative strength of the weak nuclear force??
$$
10^{-6}
$$

##### What is the relative strength of the gravitational force??
$$
10^{-40}
$$

##### What is the range of the strong nuclear force??
$$
\approx 3 \text{fm}
$$

##### What is the range of the electromagnetic force??
$$
\infty
$$

##### What is the range of the weak nuclear force??
$$
\approx 1 \text{fm}
$$

##### What is the range of the gravitational force??
$$
\infty
$$

##### Which of the 4 fundamental forces is the weakest??
Gravity.

##### When is the strong nuclear force attractive??
Between $3 \text{fm}$ and $0.5\text{fm}$.

##### When is the strong nuclear force repulsive??
At distances less than $0.5\text{fm}$.

### 2022-02-03
##### What, according to the Standard Model, comes with every type of particle??
A corresponding antiparticle.

##### What is the name of an electron's antiparticle??
A positron.

##### What two things are true about a particle's corresponding antiparticle??
* Same mass
* Opposite charge

##### If a proton is denoted $p$, how would you denote an antiproton??
$$
\bar{p}
$$

##### What, in terms of quarks, are the antiparticle versions of hadrons made from??
Antiquarks.

##### What is a fundamental particle??
A particle that has no internal structure and so cannot be divided into smaller particles.

##### What is an example of a fundamental particle??
* Electron
* Neutrino
* Muon

##### What is the process where a particle and an antiparticle are mutually destroyed called??
Annihilation.

##### Why isn't a proton or a neutron a fundamental particle??
Because they can be divided into quarks.

##### What are the two broad categories of particles in the standard model??
1. Leptons
2. Hadrons

##### What is "lepton" Greek for??
"Light", because the particles are light.

##### How can you remember that hadrons have mass??
Think "the large hadron collider", it has to shove things with mass into one another.

##### What are the 6 leptons??
1. Electron
2. Muons
3. Tau
4. Electron neutrinos
5. Muon neutrinos
6. Tau neutrinos

##### What is a lepton??
A fundamental particle that does not experience the strong nuclear force.

##### What is a hadron??
A non-fundamental particle that do experience the strong nuclear force and decay via the weak nuclear force.

##### What are all hadrons made from??
Quarks.

##### What are the two sub-categories of hadrons??
1. Baryons
2. Mesons

##### In terms of the sub-categories of hadrons, what is most of ordinary matter made from??
Baryons.

##### In terms of the sub-categories of hadrons, which consist of three quarks??
Baryons.

##### In terms of the sub-categories of hadrons, which consist of quark-antiquark pair??
Mesons.

##### What is true about the quark-antiquark pair in a meson??
The quarks are not of the same type, otherwise they'd annihilate one another.

##### What are the six quarks??
1. Up
2. Charm
3. Top
4. Down
5. Bottom
6. Strange

##### What is the charge of the up, charm and top quarks??
$$
+2/3 e
$$

##### What is the charge of the down, strange and bottom quarks??
$$
-1/3 e
$$

##### What combinations of quarks makes a proton??
$$
u, u, d
$$

##### What combination of quarks makes a neutron??
$$
d, d, u
$$

##### How can you work out the overall charge of a particle from its quarks??
Add them together.

##### What combination of quarks makes an electron??
Trick question -- electrons are not made of quarks.

##### What combination of quarks makes an antiproton??
$$
\bar{u}, \bar{u}, \bar{d}
$$

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