1. Particle Physics and The Standard Model

2. What are the Most Important Questions?
A large portion of particle physics asks:
“What is the smallest?”

3. What are the Most Important Questions
Atomic Theory

4. What are the Most Important Questions
Once we understood the atom, we realized there were different kinds of atoms
….so we organized them

5. The Standard Model
A theory that explains the properties, behaviors and interactions of the elementary particles and the fundamental forces

6. The Standard Model 12 Particles 4 Forces 6 Quarks 6 Leptons
Model is composed of …
12 Particles
6 Quarks
6 Leptons
4 Forces
Bosons (Force Carriers/Gauge Bosons)

7. Disclaimer
*This material touches on the origins of the universe
*This material is presented to ensure your awareness of the current scientific theory, not to influence any belief systems.

8. How did we know there was anything smaller?
Cosmic Rays (from outer space)
Earth receives high- energy beams of radiation from outer space.
Beams strike and interact with particles in our atmosphere

9. Cosmic Rays Caused particles to break apart into smaller pieces
We began to study these, but could not accurately predict where these rays would hit

10. On Earth, without producing Cosmic Rays, we break atoms apart with ‘atom smashers’ aka particle accelerators
Most Famous: Large Hadron Collider (LHC)
17 miles in diameter
Spans across the France- Swiss Border

11. When Atoms Smash…
Particles are accelerated close to the speed of light and then…
Particles break apart into…Energy
…which then forms into any number of different particles

12. The Standard Model - Hadrons
*We used to think protons, neutrons, and electrons were as small as we could go…
WRONG!
Protons and Neutrons are particles in a category called Hadrons
Hadrons  made up of …
Quarks

13. The Standard Model - Quarks
Quarks – Fundamental particles that make up other particles. Never seen alone, always in combinations
Quarks: Up
Charm
Top
Down
Strange
Bottom

14. The Standard Model - Leptons
Leptons – Fundamental particles not involved with the nucleus, nor do they combine with other leptons
Leptons:
Electron
Muon
Tau
Electron Neutrino
Muon Neutrino
Tau Neutrino

15. When do I see these?
Likelihood of seeing a particle is based on stability and weight.
Generation one lightest and most stable.
Generation two - next in stability
Generation three - largest and least stable

16. The Standard Model - Forces
All of the universe can be explained by four fundamental forces 4
Gravitational Force 2
Electromagnetic Force 1
Strong Force 3
Weak Force
…Strongest force?
At the beginning of the universe, it has been hypothesized that these four forces were united in a grand unified theory

17. The Standard Model - Bosons
Bosons – Have different properties than quarks and leptons But also differ in function.
Force Carrier Bosons:
Photon -
Force carrier for electromagnetic forces
Z and W Bosons -
Force carriers for the weak force
Gluon-
Force carrier for the strong force

18. Main Categories Bosons Hadrons Mesons Fermions Baryons
Composite Particles (Made from combinations of fermions)
Involved with the Fundamental Forces
Mesons
Fermions
Baryons
Fundamental Particles (Nothing smaller that we know of)
Protons and Neutrons
Quarks
Leptons

19. The Standard Model – Higgs Boson
Higgs Boson – Same properties as the other bosons (physically) BUT has a different function
This particle gives mass to other particles.
Without mass, particles cannot interact.

20. The Standard Model – The Higgs Field
Higgs particles are part of the Higgs Field – which all other particles interact with.
As particles move through the Higgs Field, some have a high level of interactions, more mass
Some have less interactions, less mass

21. Why Do We Need Mass? Newton’s Law of Universal Gravitation
A force of attraction exists between any objects with mass