Mesons and strangeness

Question 1

What mesons do you need to know about?

Answer 1

• pions
• kaons

Question 2

How were these mesons discovered?

Answer 2

• in cosmic rays
• cosmic rays are a source of both particles
• you can observe the tracks of these particles in a cloud chamber

Question 3

How do mesons interact with baryons?

Answer 3

• via strong interaction

Question 4

What are pions?

Answer 4

• lightest meson
• can have any charge
  
  • three version

Question 5

How are pions produced?

Answer 5

• many pions are produced in high-energy particle collision like those at the CERN particle accelerator

Question 6

What are kaons?

Answer 6

• heavier mesons
• more unstable that pions
• short life time

Question 7

What do kaons decay into?

Answer 7

• pions

Question 8

What are the properties of the quarks?

Answer 8

• up
  
  • +2/3 charge
  • +1/3 baryon number
  • 0 strangeness
• down
  
  • -1/3 charge
  • +1/3 baryon number
  • 0 strangeness
• strange
  
  • -1/3 charge
  • +1/3 baryon number
  • strangeness of -1

Question 9

What do cosmic rays consist of?

Answer 9

• investigations showed that cosmic rays were fast-moving protons or small nuclei
• they collide with gas atoms in the atmosphere, creating a shower of particles that can be detected at ground level

Question 10

What are the types of interaction that mesons go through>

Answer 10

• strong
• and electromagnetic in charged mesons

Question 11

Give the characteristics of a strange particle that make it different from a particle that is not strange?

Answer 11

• longer half life than expected
• decay through weak interaction