Checklist for VL-02:

slides 8ff:

(1)
In the slides the covariance against global and local transformations of the 
phase of the spinor was checked and occasionally restored by the covariant 
derivative. Can you do the same exercise for the phase of the wave function 
in the case of the Klein-Gordon equation. 

slide 10:

(2)
A question from VL-01 revisited: can you see here why the Gauge fields of the 
SM are predicted with spin-1?

slide 11:

(3) Comment:
Please note: in the SM a gauge field is something completely different from a 
fermionic matter field. The gauge field transports gauge information from 
space point A to space point B. In this sense it is not a localized object. In 
consequence, and in contrary to a fermionic matter field it cannot be observed 
as a free particle. The sketch shown in this slide is not a complete Feynman 
diagram. In a complete Feynman diagram you wont see free Gauge boson _legs_. 
Many experimental particle physicists do not understand this point very well, 
or are very sloppy in it. Can you imagine actually where the common 
mistreatment of Z, W, and H bosons as freely observable particle comes from? 
Or the other way round: under what conditions would this question have never 
been raised. This question will be re-addressed at the end of the lecture. 

slide 14:

(4)
Do you understand where the prediction of Gauge boson self-interactions comes 
from in the SM? In consequence a measurement of Gauge boson self-interactions 
would be one of the cleanest evidences of the gauge structure of the SM. This 
point will be re-addressed during the lecture.

slide 22:

(5)
Do you understand the slopes of the shown figure? E.g. why is the slope 
corresponding to the blue points smaller than the slope corresponding to the 
red points? How much is it actually smaller? You should be able to give clear 
answers to both questions.

slide 23:

(6)
Do you understand the course of the measured CC cross section? To answer this 
question for yourself check the form of the propagator of the W boson exchange 
and check the position of Q**2=mW**2 in the shown graphs. In consequence how 
could you estimate the W mass (as a parameter of the SM) from such measurements?

(7) Comment:
What resolves the problems of divergences is not the fact that the W boson does 
have a finite mass, but the fact that the existence of mediating fields/parti-
cles prevent point-like interactions. This is b.t.w. no novelty: in classical 
electrodynamics the potential of the electrical field goes to infinity for 
r->0, as all of you know. What happens is that quantum mechanics (in form of 
QED) introduces a minimal cut-off distance, via the uncertainty principle of 
Heisenberg to regularize this behavior. If you calculate a QED cross section 
by hand in Pauli-Villars regularization you will see this cut-off explicitly. 
It still has to be introduced by hand (i.e. by your experimental conditions). 
The non-trivial specialty of the SM is the "promise" that this is always 
possible, i.e. that the SM is renormalizable.

slide 27:

(8) Comment:
To be more precise the SU(2)L acts on the components of the SU(2)L doublets, 
while the U(1)Y acts on the SU(2)L doublet as a whole. 

slide 33:

(9) Comment:
Please note that the Gauge field B couples to the left and right-handed parts of 
the fermions with different coupling strengths YL and YR. It is essential for 
the SM that this is possible. Note that what is called lepton universality only 
refers to the constant "g" in the slides, which originates from the non-Abelian 
Gauge. This is indeed the same for all lepton flavors (please check). The con-
stant "g'", which is related to the Abelian Gauge does not imply such a beha-
vior. In the SM this is manifest e.g. by the different hypercharges Yi. 

slide 35:

(10)
Do you understand what "as desired" means on this slide? 

slides 36ff:

(11)
On slide 22 you have learned that the coupling of the W bosons is maximally 
parity violating. Is this also true for the coupling of the Z boson? Is it 
parity violating? If yes is it maximally parity violating? Is the coupling of 
the photon parity violating? Give a clear reasoning with all your answers.