Particle X has a strangeness of –1 and decays to produce a proton and a pion.
(a)
Deduce the quark structure of particle X.
[3]
Question 1b
Marks: 3
A strange quark decays in the following way
(b)
Deduce particle Y.
[3]
Question 1c
Marks: 3
(c)
Hence, draw a Feynman diagram at the quark level for the decay of particle X.
[3]
Question 2a
Marks: 3
a)
Explain why the discovery of the Higgs Boson was of crucial significance.
[3]
Question 2b
Marks: 3
(b)
Draw a Feynman diagram for the interaction
Assume that the time axis is from left to right.
[3]
Question 2c
Marks: 3
(c)
Explain why multiple hadrons have been produced in this reaction.
[3]
Question 3a
Marks: 3
A young student of physics reads up about particles and anti-particles.
In their physics lesson, they excitedly tell their teacher how they learned that a proton has an anti-particle called an anti-proton, and the neutron has an anti-particle called an anti-neutron.
They go on to say that, since the neutron is neutrally charged, it is its own anti-particle.
(a)
Identify the student’s misconception and explain why they are incorrect.
[3]
Question 3b
Marks: 2
(b)
Suggest another particle which is an example of being its own anti-particle and explain your reasoning.
[2]
Question 3c
Marks: 3
Interactions between protons and neutrons can temporarily violate conservation laws.
One such interaction is shown.
(c)
(i)
Identify the type of interaction shown.
[1]
(ii)
By referencing the properties of the exchange particle, explain how it temporarily violates conservation laws.
[2]
Question 4a
Marks: 4
The baryon decuplet is a vision tool used by particle physicists to classify groups of particles called baryons.
(a)
Discuss the properties of baryons.
[4]
Question 4b
Marks: 3
In the baryon decuplet, strangeness S is plotted on the horizontal axes and charge Q is plotted on the diagonal axe. Some information is missing.
(b)
Deduce the quark composition of the Ω– baryon, using each axis to justify your answer.
[3]
Question 4c
Marks: 4
(c)
Deduce the quark composition and an appropriate symbol for the missing baryon.
[4]
Question 5a
Marks: 3
(a)
(i)State two particles that are their own antiparticle.
[2]
(ii) Explain why K0 is not its own antiparticle.
[1]
Question 5b
Marks: 3
(b)
The K0 meson decays into two pions and has a strangeness of 1. State the decay equation at the quark level for the K0 meson.
[3]
Question 5c
Marks: 4
Heavier quarks can decay into lighter quarks by exchanging a virtual particle that meditates the type of interaction. This particle can then decay into a quark and its equivalent anti–quark.
(c)
Draw a Feynman diagram for the decay of the K0 meson at the quark level. Clearly label the K0 meson and the two pions.
[4]
Question 5d
Marks: 4
Muons decay via the same interaction as the K0 meson into leptons. One such decay is
(d)
(i)
Complete the missing particle in the decay.
[1]
(ii)
Draw the Feynman diagram for the decay of a negative muon, (μ–). Clearly label the time axis.