Particle Physics Questions
Q2.
(a) Hadrons are a group of particles composed of quarks. Hadrons can either be baryons or mesons.
(i) What property defines a hadron?
Hadrons are particles that experience the strong (nuclear) force/interaction.
(ii) What is the quark structure of a baryon?
A Baryon is made up of three querks.
(iii) What is the quark structure of a meson?
A meson is made up of a quark and an anti-quark.
(3 marks)
(b) State one similarity and one difference between a particle and its antiparticle.
Similarity: the same (rest) mass or (rest) energy
Difference: opposite charge, opposite baryon number or opposite lepton number
(2 marks)
(c) Complete the table below which lists properties of the antiproton.
|
Charge/C |
baryon number |
quark structure |
antiproton |
|
-1 |
|
-1 for each mistake or omission
(2 marks)
(d) The 
is an example of a meson with strangeness –1.
It decays in the following way:
(i) State, with a reason, what interaction is responsible for this decay. (2 marks)
Weak interaction because strangeness is not conserved.
(ii) State two properties, other than energy and momentum, that are conserved in this decay.
- charge
- baryon number
- (muon) lepton number
Any two
(2 marks)
(Total 11 marks)
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