# Questions tagged [notation]

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### Meaning of the $\delta$ notation [duplicate]

Two examples I've seen of this so far are in statistical mechanics, when looking at the work done on a system: $$dW=-\frac{1}{\beta}\frac{\partial \ln{Z}}{\partial V}\delta V$$ and in the Noether ...
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### Terminology for the symmetric vector product on the Bloch sphere

I was reading the paper "The extended Bloch representation of quantum mechanics and the hidden-measurement solution to the measurement problem" by Diederik Aerts, Massimiliano Sassoli de Bianchi. ...
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### Taking the Hamiltonian eigenvalue problem into position space?

I'm having a hard time notationally understanding the relationship of: $$\hat{H} \vert{\psi}\rangle = E\vert \psi\rangle$$ and $$\hat{H} \psi(x) = E\psi(x)$$ Here's my thought process: Starting ...
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### Question about Einstein summation convention

I'm dealing with the following: $$\eta^{\alpha \mu} \eta_{\alpha \nu} \phi,_{\beta \mu}$$ $$\eta^{\alpha \beta} \phi,_{\alpha \beta}$$ where $\eta$ is the Minkowski metric and $\phi$ is a function ...
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### Confusion about expressing an inner product using the Einstein summation convention

I think this likely comes down to the following expression, $$g’^{ab}e’_a e’_b = \delta ^a_b$$ Is this in agreement with the Einstein summation convention? Because even though the two indices are ...
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### Why can we 'act on the left' with an operator?

This comes from notes on perturbation theory I am learning in class. I have seen this a few times but never really understood it: how is it that we can apply an operator to the conjugate state on the ...
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### What does it mean “differentiation with respect to the coordinates of particle 1 or 2”?

I was reading Introduction to Quantum Mechanics by Griffiths. In Chapter 5, Identical Particles, I came across the notation $\nabla_1$ and $\nabla_2$. Griffiths writes that it means "differentiation ...
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### How does a linear operator act on a bra?

I'm studying QM from Shankar. He introduces linear operators and says that an operator is an instruction for transforming one ket into another. But then a few lines below he says operators can also ...
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### Is Schwarzschild's solution in his original paper consistent with current solutions? [duplicate]

I was reading the Schwarzschild's original paper where he derives the Schwarzschild metric for the first time(The english translated version found in arXiv : On the Gravitational Field of a Mass ...
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### Particle notation: What does the asterisk stand for?

For instance, what's the difference between $\Sigma^0$ particles and $\Sigma^{0*}$ particles? I know they have the same quark configuration $sdu$, so how exactly are they different? Some context: I'm ...
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