particle conservation rules

Question 1

Particle interaction rules

Answer 1

the following properties are conserved in particle interactions:

• momentum
• mass- energy (E = mc^2)
• charge (+,-,0)
• lepton number
• baryon number
• strangeness

Question 2

Charge conservation

Answer 2

“the total charge after an interaction is equal to the total charge before an interaction”

e. g. beta decay (n–> p + e- + v-)
- charge before= 0
- charge after= (+1) + (-1) + 0=0

Question 3

Lepton number conservation

Answer 3

“the total lepton number after an interaction is equal to the total lepton number before an interaction”

• a lepton (e.g. electron) =1
• an antilepton (e.g. antineutrino) =-1
• all other particles have lepton number =0

Question 4

Baryon number conservation

Answer 4

“the total baryon number after an interaction equals the total baryon number before an interaction”

• a baryon (e.g. neutron) =1
• an antibaryon (e.g. antiproton) =-1
• all other particles have baryon number =0

Question 5

Strangeness conserved

Answer 5

“the total strangeness after an interaction equals the total strangeness before an interaction”

• a strange particle (e.g. k+ kaon) =1
• a strange antiparticle (e.g. k- kaon) =-1
• all other particles have a strangeness =0