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Why exactly do sometimes universal covers, and sometimes central extensions feature in the application of a symmetry group to quantum physics?

Have we figured out how to analyze turbulent fluids?

Is the density operator a mathematical convenience or a 'fundamental' aspect of quantum mechanics?

Anyons as particles?

Braiding statistics of anyons from a Non-Abelian Chern-Simon theory

In a universe with four spatial dimensions would there be elementary particles with intrinsic isoclinic spin?

Gauge invariant but not gauge covariant regularization

Calculating $\mathrm{Tr}[\log \Delta_F]$

Where does a fermionic coherent state live (which Hilbert space)?

Group theory and quantum optics

Capturing (perturbatively) non-equilibrium field theory effects using "elementary" methods

Fermion boundary conditions at finite temperature

Two interacting electrons in infinite square potential - is there a solution?

Matsubara frequencies and analytic continuation - Domain and uniqueness

Significance of Dirac cones in condensed matter physics

Experimental evidence for non-abelian anyons?

Is there no mode expansion for $:e^{i k_\mu X^\mu(z, \bar z)}:$ in the free boson CFT?

Symmetry Breaking and Vacuum Expectation Values

Is there a rigorous proof that photons do not acquire mass through renormalization?

Exact solution of SU($N$) model in large $N$ limit

SUSY sigma model in QM, bosonic sector?

Can a quantum state with infinite variance of photon number be found in nature or artificially created?

Ambiguity in Beta Functions (2-loop)

Why is a particles magnetic moment proportional to its spin?

Diffeomorphism invariance for QFT in curved space

Temperature of spin-glass transition

Mathematical understanding of band energy

Entanglement entropy for finite interval using heat kernel method

Stratonovich integral in quantum field theory

Gauge invariance of non-Abelian theories under Pauli-Villars-Regularisation