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.![](../../../graphics/symbols/nuclides/ticksmall.png)
(ii) What is the quark structure of a baryon?
A Baryon is made up of three querks.![](../../../graphics/symbols/nuclides/ticksmall.png)
(iii) What is the quark structure of a meson?
A meson is made up of a quark and an anti-quark.![](../../../graphics/symbols/nuclides/ticksmall.png)
(3 marks)
(b) State one similarity and one difference between a particle and its antiparticle.
Similarity: the same (rest) mass or (rest) energy ![](../../../graphics/symbols/nuclides/ticksmall.png)
Difference: opposite charge, opposite baryon number or opposite lepton number ![](../../../graphics/symbols/nuclides/ticksmall.png)
(2 marks)
(c) Complete the table below which lists properties of the antiproton.
|
Charge/C |
baryon number |
quark structure |
antiproton |
|
-1 |
|
![](../../../graphics/symbols/nuclides/ticksmall.png)
-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:
![](3.png)
(i) State, with a reason, what interaction is responsible for this decay. (2 marks)
Weak interaction
because strangeness is not conserved.![](../../../graphics/symbols/nuclides/ticksmall.png)
(ii) State two properties, other than energy and momentum, that are conserved in this decay.
- charge
- baryon number
- (muon) lepton number
Any two ![](../../../graphics/symbols/nuclides/ticksmall.png)
![](../../../graphics/symbols/nuclides/ticksmall.png)
(2 marks)
(Total 11 marks)