1.6 Quarks and Antiquarks

Question 1

What is the quark structure of a proton?

Answer 1

Up, up, down

Question 2

What is the quark structure of a neutron?

Answer 2

Up, down, down

Question 3

What are the properties of the antiquarks?

Answer 3

The opposite properties of the quarks

Question 4

What is the quark composition of baryons?

Answer 4

• all baryons are made up of 3 quarks
• antibaryons are made up of 3 antiquarks
• the charge and baryon number of a baryon is the total charge and baryon number of its quarks

Question 5

What is the quark composition of mesons?

Answer 5

• all mesons are made of one quark and one antiquark
• pions only contain up and down quarks or up and down antiquarks
• kaons contain either a strange quark or a strange antiquark

Question 6

What is the strangeness of the K0 meson?

Answer 6

+1

Question 7

What is quark confinement?

Answer 7

It is not possible to get a quark by itself. If you supplied a proton with a lot of energy, instead of a single quark being removed the energy you supplied would just get changed into mass.

Question 8

What happens at the quark level during beta minus decay?

Answer 8

A d quark is turned into a u quark. This can only happen using the weak interaction

Question 9

What happens at the quark level during beta plus decay?

Answer 9

A u quark turns into a d quark

Question 10

Why are experiments in particle physics often carried out by a large team?

Answer 10

• particle accelerators are needed to make the particles travel at high speed, which are very expensive
• hypothesises need to be peer reviewed by other scientists to ensure they are correct
• lots of specialist skills are required to prove a hypothesis