Classification of Particles

Question 1

What are Hadrons?

Answer 1

• Hadrons are a group of subatomic particles that are made up of quarks and can interact via strong nuclear force

Question 2

What are the two classes of Hadrons?

Answer 2

• Baryons like protons and neutrons (particles that can decay into a proton and particles are made up of 3 quarks)
• Mesons like pions and kaons (particles that can’t decay into a proton and particles are made up of a quark and antiquark pair)

Question 3

State the difference of anti-hadrons

Answer 3

• Anti-baryons now have 3 anti-quarks instead of 3 quarks
• Anti-mesons quark now becomes an anti-quark and it’s anti-quark now becomes a quark
• Combination of quarks and anti-quarks don’t exist in baryons

Question 4

Describe how a baryon number is used

Answer 4

• Baryons have a baryon number of +1
• Anti-baryons have a baryon number of -1
• Particles that are not baryons have a baryon number of 0
• In all interactions, the baryon number is conserved

Question 5

What is the proton as a baryon?

Answer 5

• Proton is the most stable baryon
• Longest half-life than any baryon
• Particle that all baryons eventually decay into
• Lightest baryon (which is why it is stable)
• Radioactive decay occurs when heavier particles decay into lighter particles
• A decay of the proton would therefore violate the conservation of baryon number

Question 6

What are gluons/pions?

Answer 6

• Pions (π–mesons) can be positive (π+ ), negative (π- ) or neutral (π 0)
• Lightest meson (most stable meson)
• Both pions and gluons are exchange particles of the strong force
• Gluons bind quarks together (strong interaction)
• Pions bind nucleons together (strong nuclear force)