Past Paper Questions

1
Past Paper Questions

• RQM Klein Gordon
• Kinematics four-momentum
• Feynman Graphs
• Discrete Symmetries Helicity

2
RQM- Klein-Gordon
June 2001 Q1
3
Kinematics four momentum
Question 1 June 2002
4
Feynman Graphs
June 2002 1st part
1. a) One decay mode of the Z is Z???- The t
subsequently decays. Draw Feynman diagrams for
the following t decay modes i) ?- ?e- ?t
vebar ii) ?- ?µ- vt vµbar? iii) ?- ?p- vt 3
Suppose both taus decay to electrons under what
kinematic conditions might this decay be mistaken
for Z?ee- 2 Draw a Feynman diagram for the
transition D0 ?D0. 3
5
Discrete symmetries- Helicity
2B June 2001, 2nd part
Define helicity and show that it is a
pseudoscalar quantity. Describe the experiment
of Goldhaber et al (1958) which measured the
handed-ness of the electron neutrino. Indicate
how the experimenters concluded from their
observations that the electron neutrino is left
handed. Given this result, and that the anti
electron neutrino is right handed, comment on
a) the expected mass of the neutrino, b) the
application of the charge conjugation and parity
operators (separately and together) to the
neutrino state. 12