# Tagged Questions

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### General definition of vector spinor and spin

I am looking for basic and exact definitions of fundamental physical consepts in graduate level. I reach this following definitions. Could you please help to improve these definitions. Spin: ...
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### Why must these Spinors be normalized?

I have just begun studying spin and there are two spinors mentioned: The main spinor $\chi$ and the spin-up spin down spinors (eigenspinors) $\chi_+ ,\chi_-$. I learned that the main spinor is a ...
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### Helicity and Chirality

Does the concept of both helicity and and chirality make sense for a massive Dirac spinor? A massive electron in chiral basis is written as a column made up of $\psi_L$ and $\psi_R$. What are the ...
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### Wavefunction of an electron

Electron is a spin $\frac{1}{2}$ particle, so needs 2-component wave function but the Dirac theory of electron is based on 4-component wave function, are all components of it independent or only two ...
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### Why normalizing spin state is different? Why no need dxdydz?

An electron in a spin state: $$X=A\quad\begin{pmatrix} 2i\\2\end{pmatrix}\quad$$ In order to get A, I have to normalise it, my question is how should write? Since I have to normalise why no need ...
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### Spinors and Probabilities of Electron-Positron Pair

Question: An electron and positron are moving in opposite directions, and are in the spin singlet state. Two Stern-Gerlach machines are orientated in some ...
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### Energy Spectrum of pair of spin-1/2 particles with general Hamiltonian

I found this problem, and so far I am stumped. I was wondering if anyone wanted to solve it with me, or help me calculate eigenvectors, or just give insight on my questions. Consider a system of ...
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### What're the relations and differences between slave-fermion and slave-boson formalism?

As we know, in condensed matter theory, especially in dealing with strongly correlated systems, physicists have constructed various "peculiar" slave-fermion and slave-boson theories. For example, For ...
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From the Schrödinger equation of a system I'm investigating, where the wave function is a 4-component spinor of coefficients $C_1, C_2, C_3, C_4$, I am able to obtain the expression $\begin{pmatrix} ... 2answers 406 views ### Two ways to form SU(2) singlets? I am trying to reconcile the two ways of forming SU(2) singlets out of a pair of doublets. Method (1): If$v=\begin{pmatrix}v^1\\ v^2\end{pmatrix}$and$w=\begin{pmatrix}w^1\\ w^2\end{pmatrix}$are ... 4answers 829 views ### Could one argue that h (Planck constant) and$\hbar\$/2 (Dirac constant) are in fact independant constants?

My question is very naive and could sound strange but it seems to me natural in so far as the Planck constant is related to the first quantization (of newtonian particle mechanics/galilean relativity) ...
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### How quantum field transforms in case of some particular spin

Except when a particle is spin-0, field of all particles transforms when frame of reference is changed, and this defines what spin is. The question is, specifically how does the quantum field ...
Generally, Gamma matrices could be constructed based on the Clifford algebra. $$\gamma^{i}\gamma^{j}+\gamma^{j}\gamma^{i}=2h^{ij},$$ My question is how to generally ...