quantum mechanics - Essential background for QFT study

The preface to Mark Srednicki's "Quantum Field Theory" says that to be prepared for the book, one must recognize and understand the following equations:

$$\frac{d\sigma}{d\Omega} = |f(\theta,\phi)|^2, \qquad (1)$$ $$a^{\dagger}|n\rangle = \sqrt{n+1} \space |n+1\rangle, \qquad (2)$$ $$J_{\pm} |j,m \rangle = \sqrt{j(j+1)-m(m\pm 1)} \mid j,m \pm 1 \rangle, \qquad (3)$$ $$A(t) = e^{+iHt/\hbar}Ae^{-iHt/\hbar}, \qquad (4)$$ $$H = p\dot{q}-L, \qquad (5)$$ $$ct'=\gamma (ct-\beta x), \qquad (6)$$ $$E=(\mathbf{p}^2c^2+m^2c^4)^{1/2}, \qquad (7)$$ $$\mathbf{E} =-\mathbf{\dot{A}}/c-\mathbf{\nabla} \varphi. \qquad (8)$$

I am certainly not ready to dive into this book, so I would like some help identifying these equations and learning more about their fundamental usefulness.

I don't recognize (1), but (2) looks like a quantum mechanical creation operator? I thought those were only really useful in the context of the harmonic oscillator problem, but maybe everything is just a complicated HO problem? (3) has to do with angular momentum? (4) is a plane wave solution to the Schrodinger Eqn? (5) is the classical mechanics Hamiltonian, with cannonical coordinates? (6) is the relativistic Lorentz transformation. (7) is the general form of mass energy equivalence from SR. (8) is the electric field expressed as vector and scalar potentials? Is that really the only E&M machinery required?

Any insight as to why these particular expressions are relevant / important / useful to QFT is also appreciated. Also, where are the statistical mechanics ideas hiding? In the QM?

Answer

They are:

1. 
   

   The definition of the scattering cross-section in terms of the scattering amplitude.

   
   


2. 
   

   HO/photon creation operator.

   
   


3. 
   

   Angular momentum raising and lowering operator.

   
   
   


4. 
   

   Heisenberg equations of motion for an operator.

   
   


5. 
   

   Definition of the Hamiltonian.

   
   


6. 
   

   Lorentz transformation.

   
   



7. 
   

   Relativistic equation for energy.

   
   


8. 
   

   Electric field in terms of scalar and vector potentials.

   
   

(1) is because you calculate a lot of cross-sections, (2) & (3) because you use a lot of raising and lowering operators, (4) because you need to know the difference between the Schrodinger, Hisenberg, and Interaction pictures of QM, (5) becuase you use both Lagrangians and Hamiltonians, (6) & (7) for basic special relativity, and (8) for basic E&M.