2 Quarks and Leptons

Question 1

what are cosmic rays?

Answer 1

high energy particles (fast moving protons or small nuclei) that travel through space from the stars

Question 2

what is created when cosmic rays crash into the gas particles in the atmosphere?

Answer 2

new short lived particles and antiparticles as well as photons

Question 3

what are the properties of the muon?

Answer 3

• negatively charged
• rest mass of over 200 times that of an electron

Question 4

what are the properties of the pion (or pi meson)?

Answer 4

• can be positively or negatively charged or neutral
• rest mass is greater than a muon but less than a proton

Question 5

what are the properties of a kaon (or K meson)?

Answer 5

• can be positively or negatively charged or neutral
• rest mass greater than a pion but less than a proton

Question 6

what are strange particles?

Answer 6

particles which decay into pions and take longer to decay than expected

Question 7

what can kaons decay into?

Answer 7

pions or a muon and an antineutrino or an antimuon and a neutrino

Question 8

what do muons decay into?

Answer 8

an electron and an antineutrino
antimuons decay into a positron and a neutrino

Question 9

what do charged pions decay into?

Answer 9

• a muon and an antineutrino
• an antimuon and a neutrino

Question 10

what do neutral pions decay into?

Answer 10

high energy photons

Question 11

What are hadrons?

Answer 11

Particles and antiparticles that can interact through the strong interaction

Question 12

What are leptons?

Answer 12

Particles and antiparticles that do not interact through the strong interaction

Question 13

What is a baryon?

Answer 13

Protons and other hadrons that decay into protons, either directly or indirectly

Question 14

What are mesons?

Answer 14

Hadrons that do not include protons in their decay products (kaons and pions)

Question 15

Why are there different types of neutrinos?

Answer 15

The neutrinos and antineutrinos produced in beta were different from those produced by muon decays

Question 16

What are the two types of neutrinos?

Answer 16

Electron neutrinos and muon neutrinos

Question 17

What can a neutrino or antineutrino do in interaction between a lepton and a hadron?

Answer 17

They can change into or form a corresponding charged electron

Question 18

What happens during muon decay?

Answer 18

• The muon changes into a muon neutrino
• An electron is created and corresponding antineutrino is also created

Question 19

When when is strangeness conserved?

Answer 19

During the strong interaction

Question 20

What is the quark composition of mesons?

Answer 20

A quark and an antiquark

Question 21

What is the quark combination of baryons?

Answer 21

Three quarks

Question 22

What happens in terms of quarks in beta plus decay?

Answer 22

Are down quark in the neutron changes to an up quark
A beta plus particle and a neutrino is also emitted

Question 23

What happens in terms of quarks during beta plus decay?

Answer 23

And up quark in the proton changes to a down quark in the neutron
A beta plus particle and a neutrino are also emitted

Question 24

What is conserved during all particle interactions?

Answer 24

Energy
Charge
Lepton number
Baryon number

Question 25

What is not conserved in weak interactions?

Answer 25

Strangeness

Question 26

What type of quarks do kaons always contain?

Answer 26

Strange quarks