How do we know from representation theory that a massless spin-1 particle has only two polarizations?
11181
Counting degrees of freedom of gauge bosons
37022
Is there an elegant proof of the existence of Majorana spinors?
2613
Difference between spin and polarization of a photon
116427
$(c^{\mu}\partial_{\mu}-m)\phi(x)=0$ not Lorentz-invariant?
26125
Does the canonical commutation relation fix the form of the momentum operator?
90221
Regarding the Weyl spinor and its transformation properties
71626
Superposition of distinct vevs in spontaneous symmetry breaking
123595
Representations of Direct Sum of Lie Algebras
73624
Why is orbital angular momentum quantized according to $I= \hbar \sqrt{\ell(\ell+1)}$?
104657
Wave/particle duality
134962
What causes the Pauli exclusion principle (and why does spin 1/2 = fermion)?
153205
Why is the $(\frac{1}{2},\frac{1}{2})$ representation of the Lorentz group realized as the vector space of Hermitian $2\times 2$ matrices?
13292
Which of $\{J_0,J_1,J_2\}$ and $\{J_0,J_+,J_-\}$ is a generator for the Lie algebra $\mathfrak{su}(2)$?
116799
Theoretical Proof of Pauli's Exclusion Principle
58445
What does the Canonical Commutation Relation (CCR) tell me about the overlap between Position and Momentum bases?
81188
$SO(3)$, orbital angular momentum, vector product
39244
References on the non-compositeness of the known elementary particles