1. Physics 4 – April 18, 2019 Agenda:
P3 Challenge – Distinguish between a hadron, a baryon and a meson?
Objective:
7.3 Structure of Matter
Assignment:
p307 #28-38
Agenda:
Homework Review
Particle Characteristics
Standard Model
Particle Conservation Laws
Particle Reactions
Get out p284 #14-15 and p307 #25-27
for a HMK check

2. Quark characteristics
Symbol
Baryon #
Charge
Strange Up u
1/3
+2/3
Down d
–1/3 s –1
Charm c
Top t
Bottom b
Ex: Proton = u,u,d 1/3 + 1/3 + 1/3 = 1 Baryon # Charge = +2/3+2/3–1/3 = +1
Antiparticles have the same mass, but opposite baryon #, charge, strange, color.
Ex: Pion+ = u, d 1/3 – 1/3 = 0 Baryon # Charge = +2/3+1/3 = +1

3. Fundamental forces, Bosons
There are four fundamental forces: Electromagnetic force, Strong nuclear force, Weak nuclear force, and Gravity.
All other forces can be understood as a fundamental interaction based on one or more of these forces.
Forces interact through exchange particles called bosons.
Force
Particle used
Acting on
Electromagnetic
photon
leptons (e.g. e-)
Strong nuclear
gluon
quarks
Weak nuclear
W / Z
Gravity
graviton
all mass

4. Relative strengths, Range of influence

5. Standard Model
The Standard Model summarizes all elementary particles, like a periodic table of particles.
6 Quarks, 6 Leptons, 4 Bosons
Predicts the existence of a Higgs particle that is to mass what the photon is to electromagnetism.
The Higgs particle is a quantum of a Higgs field which describes mass.
Observed in 2012.
Gravity remains a mystery. Gravity waves first discovered in 2015.

6. Particle Conservation Laws
All particle interactions are governed by conservation laws for
Charge
Baryon Number
Lepton Number
Strangeness
For any particle interaction/reaction, all four must be conserved or the reaction will not occur.

7. Particle Reactions 𝝁 + → 𝒆 + + 𝝊 𝒆 + 𝝊 𝝁
Check to see if this reaction is possible.
K- + p  + + n where K- = s u and + = u d
Check all 4 conservations and explain which get violated.
𝝁 + → 𝒆 + + 𝝊 𝒆 𝝊 𝝁

8. Exit slip and homework
Exit Slip – What is the anti K- particle quark structure? What is it’s charge, baryon number, lepton number and strangeness?
What’s due? (homework for a homework check next class)
P307 #28-38
What’s next? (What to read to prepare for the next class)
Read 7.3