You meant to say yes. Within the Standard Model, as you say, the photon and electron fields have different properties, therefore have to be treated as separate.
In this case, just don't forget to draw the arrows! However, this seems to me like a careless introduction of Feynman diagrams within a pedagogical text.
The diagram you show may be useful (but maybe even more so misleading) for a heuristic approach to the scattering problem. Apart from the remark that you would have to include arrows on the lines, one has to notice two important facts:
1.) In quantum field theory, scattering amplitudes are...
Yes, it is. It allows one to calculate meson, baryon and glueball spectra, form factors, and even incorporates chiral symmetry restoration at high temperature. If you're interested, take a look at some of those papers:
http://arxiv.org/abs/hep-th/0412141
http://arxiv.org/abs/hep-th/0507073...
The axial anomaly of nonabelian gauge theories actually comes from a broken U(1) symmetry.
In QCD, you have U(N_f)_L\times U(N_f)_R chiral symmetry, with both a conserved left-handed current L^\mu and a right-handed one, R^\mu. It is now possible to make a linear combination of those two...
There is a very nice website http://physics-animations.com/Physics/English/phon_txt.htm explaining your example generally (it has different masses instead of different force constants, but you can just rename the constant in the first equation on the webpage).
The animation in the bottom...
The only reason I can think of is: By defining S=k_b \log \Omega, it just works out; for an ideal gas as well as for other systems (that I can't come up with right now).
\frac{dS}{dE}=\frac {1}{T(E,...)}\, states that temperature is a measure of the increase in entropy when some energy is...
In it's strict mathematical formulation, it is restricted to string theory.
I'm not sure about Susskind and t'Hooft, but Maldacena is the one who conjectured it.
The black hole entropy was derived without explicit use of string theory, and as such it can be seen as a manifestation of the...
The holographic principle manifests itself in string theory in the form of the so-called "AdS/CFT-Correspondence". It was formulated in the late 90's by Juan Maldacena (hence it is also often called "Maldacena Conjecture") and it states a duality between a type IIB string theory on an...