1. Standard Model for Sub-atomic Particles

2. Elementary & Fundamental Particles
Democritus introduced the word which in English translates as atom
Elementary Particles
The name given to protons, neutrons and electrons
Today we use the term "fundamental" for the six types of quarks and the six leptons

3. Quarks
Quarks are fundamental matter particles that are constituents of neutrons and protons and other hadrons
Proton -- composed of two up quarks and a down quark
Neutron -- composed of two down quarks and an up quark

4. Classification of Matter
Hadrons: Particles made of quarks. Protons, Neutrons and their Anti-particles
Hadrons are further broken into Baryons and Mesons. ( both break down into Quarks)
Leptons: Are NOT made of sub particles. Electrons are examples of Leptons

5. Hadrons Hadrons break down into two groups
Baryons are made of 3 Quarks
Mesons made up of 2 quarks and anti-quarks, or 1 of each
***(charge must add up to an integer not a fraction)

6. THE STANDARD MODEL

7. Leptons
Leptons are fundamental particles that have no strong interactions
Lepton is Greek for "light particle”
Ex. The electron, but there are heavier leptons
The first to be found was the muon

8. Sample Problem A Baryon may have a charge of
Correct answer is 0e (all types of matter must have an integer charge)

9. FROM THE TEXTBOOK (i) allowed (charge and lepton number conserved)
9. a) the Weak Nuclear Force is responsible
for proton decay into a neutron
b) According to Hideki Yukawa,
the W+ boson particle mediates
this decay.
c) electron neutrino, νₑ
10. a) (i) u⁻ → e⁻ γ
(ii) p n → p π⁰
(iii) P → π⁺ π⁻
(i) allowed (charge and lepton number conserved)
(ii) not allowed (baryon number not conserved)
(iii) not allowed (charge and baryon number not conserved
b) exchange particles in the Weak Interaction can be W+ , W- , or Z bosons
Hideki Yukawa ( )
Tokyo & Kyoto Prefecture. Book, “Tabibito”

10. Neutrinos (type of Lepton)
These particles are so small that they pass right through the Earth without interacting with a single atom.

11. Strong Force
Quarks and Gluons have a type of charge that is NOT electromagnetic
The “color” charged particles are very powerful (STRONG)
Quarks are glued together with GLUONS (Nuclear Energy)

12. Weak Force
The stable matter of the universe is made up of the two least massive quarks: UP and Down and the least massive Lepton, the electron ( A Hydrogen Atom)
When a quark or lepton changes type (muons changing to an electron), this is called a “flavor” weak interaction

13. 11. Negative Kaon collides with a proton
K⁻ + p K⁰ K⁺ + X
a) Kaons belong to the meson (middle) family,
with 2 quark structure
b) proton quark structure is uud
(⅔ ⅔ -⅓) = +1
FROM THE TEXTBOOK c)
baryon number (1 = 1) and strangeness both conserved
12. a) exchange particle carries the force between particles;
said to be virtual because it is not detected during exchange
b) W- boson (since diagram shows β – decay)

14. Reference Chart : Standard Model