Conservation Laws

Question 1

What are the four properties that are always conserved?

Answer 1

• Charge
• Baryon Number
• Strangeness
• Lepton Number

Question 2

What is the conservation of charge?

Answer 2

In any particle interaction, the total charge after the interaction must equal the total charge before the interaction.

Question 3

What is the conservation of baryon number?

Answer 3

In any particle interaction, the baryon number after the interaction must equal the baryon number before the interaction.

Question 4

What is the conservation of strangeness?

Answer 4

• Strangeness is conserved only in strong interactions, in strong interactions there has to be the same number of strange quarks at the beginning as at the end.
• In weak interactions strangeness can change by, -1, 0 or +1.

Question 5

What is the conservation of lepton numbers?

Answer 5

• In any change, the total lepton number for each lepton branch before the change is equal to the total number for that branch after the change.
• Two types of lepton number have to conserved separately.