2.4 Quarks and antiquarks

Question 1

What do we call particles that decay into pions?

Answer 1

» Kaons

Question 2

What is the strangeness number?

Answer 2

» A number introduced so strangeness is always conserved in the strong interaction

Question 3

In which interaction is strangeness always conserved?

Answer 3

» Strong interaction

Question 4

How can strangeness change in weak interaction?

Answer 4

» It can change by 0, +1, or -1

Question 5

What can the properties of hadrons be explained by?

Answer 5

» Explained by the quarks inside the particles

Question 6

What is conserved in all interactions?

Answer 6

» Momentum
» Energy including rest mass energy
» Charge

Question 7

What are the three quarks you need to know for this course?

Answer 7

» Up quark
» Down quark
» Strange quark

Question 8

What is the charge of an up quark?

Answer 8

» +2/3

Question 9

What is the charge of a down quark?

Answer 9

» -1/3

Question 10

What is the charge of a strange quark?

Answer 10

» -1/3

Question 11

What is the strangeness of up-and-down quarks?

Answer 11

» 0

Question 12

What is the strangeness of a strange quark?

Answer 12

» -1

Question 13

What is the baryon number for up down and strange quarks?

Answer 13

» 1/3

Question 14

What is the baryon number for each quark?

Answer 14

» +1/3

Question 15

What is the charge of an anti-down and anti-strange quark?

Answer 15

» +1/3

Question 16

What is the charge of an anti-up quark?

Answer 16

» -2/3

Question 17

What is the strangeness of an anti-strange quark?

Answer 17

» +1

Question 18

What type of particles are mesons?

Answer 18

» Hadrons

Question 19

What does mesons consist of?

Answer 19

» An quark and antiquark combination

Question 20

What are the particles called that contain a combination of s quarks?

Answer 20

» Not called pions, but called Kaons because they decay much faster than pions

Question 21

How many uncharged kaons are there?

Answer 21

» 2
» K^0 meson
» Anti k^0 meson

Question 22

What are the 2 different types of mesons?

Answer 22

» Pions
» Kaons

Question 23

What is the quark combination of K^0?

Answer 23

» Anti-strange, down quark

Question 24

What is the quark combination of k^+?

Answer 24

» Anti-strange, up quark

Question 25

What is the quark combination of k^-?

Answer 25

» Strange, anti-up quark

Question 26

What is the quark composition of the Antiquark k^0?

Answer 26

» Anti down, strange quark

Question 27

What is the quark composition of pi^+?

Answer 27

» Up, anti down quark

Question 28

What is the quark composition of pi^-?

Answer 28

» Anti - up, down quark

Question 29

What is the quark composition of pi^0?

Answer 29

» Anti down, down » Anti up, up

Question 30

What do baryons and antibaryons consist of?

Answer 30

» They are hadrons » Consist of three quarks for a baryon » Consist of three antiquarks for an antibaryon

Question 31

What is the quark composition for a proton?

Answer 31

» uud

Question 32

What is the quark composition for a neutron?

Answer 32

» udd

Question 33

What is the quark composition for an antiproton?

Answer 33

» Anti(udd)

Question 34

What is the sigma particle?

Answer 34

» Baryon which contains a strange quark

Question 35

Why is the proton the only stable baryon?

Answer 35

» A free neutron can decay into a proton, releasing an electron and an eletron antineutrino

Question 36

What quark changes in beta-decay?

Answer 36

» Quark composition of a neutron is udd » To make a proton, a d has to change to an up quark