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Comparing quantum and natural Hamiltonian dynamical systems for the hydrogen atom: Why is quantum preferred?

The quantum model for the hydrogen atom is a Hamiltonian dynamical system based on Schrödinger operator $H$. When compared with the physical atom it has important shortcomings. First and foremost the ...
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6 views

Where to find a Path Integral treatment of 1D Quantum Heisenberg model or Quantum Spin Chain?

All: Where to find a Path Integral treatment of 1D Quantum Heisenberg model or Quantum Spin Chain ? I would like to find a detailed calculation of path amplitude in such situation. I did some ...
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7 views

Single slit or double slit

Are there any mathematically rigorous problems on single slit diffraction problems that I could read about, that concerns itself with more geometric optics as well? All the examples in my book are so ...
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0answers
9 views

Quantum secret sharing

I was reading an article https://journals.aps.org/pra/abstract/10.1103/PhysRevA.71.044301 It had 3 parties Bob, Alice and Charlie. They agree on sharing a classical secret quantum mechanically. The ...
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8 views

Einstein–Brillouin–Keller quantization rule, what does it really mean?

The Einstein–Brillouin–Keller method is a quantization rule going from classical mechanics to quantum mechanics, according to wikipedia: I have several question regarding the above description: what ...
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12 views

how to know the (c-)parity of a particle?

As a following up to Why does the parity of a meson have a "+1" in it? I have another question: Why does the photon have a c-parity of -1? Is it due to some advanced calculation or can I ...
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16 views

Why is force invariant under a Galilean transformation? [duplicate]

I've had a look around online, but I haven't been able to find something which answers this in a way I understand. Essentially, I'm trying to figure out why force is invariant under a Galilean ...
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0answers
9 views

Simple question on Giamarchi's book

I have trouble from Eq.(2.62) to Eq.(2.63) in Giamarchi's "Quantum Physics in One Dimension". The book says as follows, but I think that some terms are missing. By straight computation of $\rho(r)\...
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1answer
22 views

Why the eigenvalues of $L^2$ never take half-integral values?

In general, if a set of three hermitian operators $J_i (i=1,2,3)$ satisfy the commutation relation $[J_i, J_j]=i\hbar\epsilon_{ijk}J_k$, then it follows that the eigenvalues of $j(j+1)\hbar^2$ of $J^2\...
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1answer
14 views

Method of resolution of forces numerical Question

The resultant of two forces F1 and F2 is at right angles to F1. Determine the angle between the forces.
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1answer
14 views

Statics - Equilibrium of Rigid Bodies Worksheet Question

I have a standard worksheet problem involving free body diagrams and equilibrium of a rigid body. I need to calculate the reactions at A and B for the simply supported frame in the image below. I've ...
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1answer
19 views

Linearizing Equations (Question given below):

This question is mainly asking to rewrite a different graph equation (maybe parabolic, curved, etc) and changing it to a normal linear equation in the form y = mx+b. The question 5 and 6 can be seen ...
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0answers
7 views

Calculating natural ventilation rate of a room

How can I calculate the natural ventilation rate of a room? Which law of fluid suits best for this situation?
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0answers
24 views

(Giamarchi) Physical meaning of $\Psi^\dagger(r)\Psi^\dagger(r+a)$

I am currently reading Giamarchi's "Quantum Physics in One Dimension". The below is the part of the book: Question: 1. Eq. (2.72) of the book defines $$O_{SU}(r)=\Psi^\dagger(r)\Psi^\dagger(r+a)$$ ...
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18 views

Hysteresis in ferromagnets

In my text it is given that the magnetic susceptibility X = I/H but in another it was dI/dH. But second can be used to draw the hysterisis graph so I think the second must be correct. X is dependent ...
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0answers
34 views

Fictious force energy

In a general non inertial system four fictitious forces arise: 1 coriolis Force, 2 centrifugal Force, 3 azimuthal Force, 4 "translational" Force (due to linear acceleration of the origin of the ...
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0answers
7 views

Phase Shift in Cirac-Zoller Quantum Gate

How can we see that in the Cirac-Zoller phase gate, a $2 \pi$ laser pulse gives us a phase shift of $(-1)$? We apply a $2 \pi$ pulse tuned to the red sideband transition, which corresponds to a ...
2
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0answers
19 views

Doppler effect of light

Doppler effect for light is created for relative motion . But shouldn't light always approach us at the same velocity 'c' regardless of the relative speed ?Then how does Doppler effect work ?
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30 views

Can a field $\phi$ obey both the scalar relation and the fermi relation?

Let $L_{\text{scalar}}=\frac{1}{2}\eta^{\mu\nu}\partial_\mu \phi \partial_\nu \phi$ be the scalar lagrangian and $L_{\text{fermion}}=i\psi \gamma^u \partial_\mu \psi$ be the fermionic lagrangian. Can ...
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1answer
19 views

Is there a difference between metal waveguides in microwave frequencies and dielectric waveguides in optical frequencies?

Do they work the same way? Do metal waveguides in MW also work through total internal reflection like in optical waveguides?
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1answer
30 views

Energy stored in a field - isolated system

If I consider an isolated system, e.g. two masses, i know I can apply the energy conservation principle considering the kinetic energy and the gravitational potential energy of the two masses. But to ...
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3answers
23 views

How to determine the direction of components of force while solving the problems related to hinge force?

There are two different directions of horizontal force in two different situations. Why?
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0answers
21 views

How to formally integrate the geodesic equation given the Christoffel symbols?

Given the geodesic equation $$\ddot{x} + \Gamma^a_{\;bc}\,\dot{x}_b\dot{x}_c = 0$$ with initial conditions, say $x(\lambda=0)=0,\dot{x}(\lambda=0)=v^a$, and all the data of Christoffel symbols ...
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0answers
10 views

Correct method for error propagation in pseudo-data approach using model

I want to compute the error on the integral over experimental data $(y_i,\delta y_i)$ in a pseudo-data approach using model ($x_i$ are assumed to be known error-less numbers). If I were using direct ...
2
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2answers
30 views

How to convert $\rm kg/m^3$ to $\rm J/m^3$ for natural gas and biogas?

I want to convert from mass density to energy density: Natural gas has a density of $0.8\: \rm kg/m^3$. Biogas has $1.15\:\rm kg/m^3$. I want to convert them into $\rm J/m^3$ so that I can ...
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0answers
25 views

Consistent calculation of the total momentum in quantum physics

When we are considering a one-dimensional case in quantum physics, we can calculate the momentum by solving the eigenvalue equation: $$ -i \hbar \frac{d}{d x} \psi(x, t) = p_x \psi(x, t).$$ If we ...
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0answers
21 views

Why is Goldstone boson not observable in the non-Hermitian QFT?

I ahve recently stumble upon a paper on the spontaneous symmetry breaking of Non-Hermitian QFT arXiv:1808.00437. On page 8 (at the end of section 3) the author claims that one can not "observe" the ...
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32 views

Crystal lattice Fourier coefficient

In solid state physics we have a periodic function over the lattice as $$f(\boldsymbol{r})=\sum_{\boldsymbol{G}}f_{\boldsymbol{G}}\mathrm{e}^{2\pi i\boldsymbol{G}\cdot\boldsymbol{r}}$$ where $$\...
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1answer
25 views

Is the strong potential repulsive for high distances?

The negative region in a potential is attractive and the positive region is repulsive. At least in case of the coulomb potential: When having a look at the strong potential it is obvious that the ...
2
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0answers
22 views

Supercurrent conservation for super-Yang-Mills in D=3,4,6,10 dimensions

I am following the book by Freedman and Van-Proeyen and this question is related to exercise 6.3. The supercurrent of a super Yang-Mills theory is given by $\mathcal{J}^{\mu} = \gamma^{\nu \rho} F^...
1
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1answer
30 views

Loss of mass in a fission reaction

I was reading a textbook for fun this summer and I had difficulty to understand this uranium 235 fission reaction: $$\ _0^1n + \ _{92}^{235}U \rightarrow \ _{38}^{94}Sr + \ _{54}^{139} Xe + 3 \ _0^...
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1answer
49 views

Show Galilean invariance of Schrödinger eq

I'm trying to show the Galilean invariance of the (time-dependent) Schrödinger equation by transforming as follows: $$ \left\{\begin{eqnarray}\psi(\vec{r},t) &=& \psi(\vec{r}'-\vec{v}t,t),\\ \...
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0answers
10 views

Solar cell: Surprising change in EL for varying PEDOT:PSS-thicknesses

I am currently working on improving a solar cell, which is partly transparent and therefore utilizes two transparent electrodes (TCO on top and PEDOT:PSS on the bottom). As PEDOT:PSS alone is not ...
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0answers
16 views

Doppler effect with two moving resonators

Sound source with frequency $\mathcal{V}_0$ is located between two moving resonators set to wavelengths of $ \lambda_1$ and $\lambda_2$, respectively. Determine speed ratio of the two resonators $\...
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17 views

Exhaustion of a gas Pressure Tank

Gas tank of the volume $V$ is exhausted with the axial piston pump. It pumps $\Delta V$ of volume per one working cycle. After how many cycles does the pressure in the gas tank reduce by $K$ times? ...
3
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2answers
59 views

Why do all fields in a QFT transform like *irreducible* representations of some group?

Emphasis is on the irreducible. I get what's special about them. But is there some principle that I'm missing, that says it can only be irreducible representations? Or is it just 'more beautiful' and ...
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0answers
11 views

Location of diffraction pattern on the image plane/detector plane

I am trying to make a spectrometer. At the moment, I have an optical setup consisting of a laser, diffraction grating and a screen/detector in a straight line. I am trying to understand how to ...
2
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1answer
38 views

Why does an egg on the bottom of a pot filled with spinning water rise to the top?

If you start stirring water contained in a cylinder shape container a vortex will form and it will pull objects to the top. Why does a vortex even form in such a way that the center gets deeper than ...
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1answer
39 views

Why is the coordinate basis never locally orthonormal in curved spacetime

In Carrolls relativity book “Spacetime and Geometry” he comments that “This is not a situation we can define away; on a curved manifold, a co- ordinate basis will never be orthonormal throughout ...
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1answer
29 views

Interference using three slits

Lets say there is a Young double slit interference apparatus, but with three slits placed at $y= - d$, $0$, $d$, and where the screen is at $X = D$ parallel to the $y$ axis. Can there be any areas on ...
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0answers
9 views

Why linear response theory is exact for quadratic Hamiltonian?

In linear response theory, we consider the Hamiltonian $H(t)=H_0 + \theta(t)H'(t)$, where $H'$ is a perturbation that is turned on $t=0$. A standard result is that for an observable $A$, $$ \langle A(...
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1answer
43 views

Why does the parity of a meson have a “+1” in it?

The parity of a meson is defined as $ P = (-1)^{L+1} $ where $L$ is the angular momentum. What does the "1" in the exponent represent?
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1answer
9 views

Change in momentum in Impulse of deformation and reformation

I was reading some text on coefficient of restitution when I encountered this , In the following you all would notice that in Impulse of deformation for particle $m_2$ we can see that change in ...
2
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0answers
53 views

Is it cold inside a black hole? [duplicate]

What is the temperature inside a black hole? It may be very cold, or very hot. Or just the surrounding temperature. Or maybe neither, because the concept of temperature makes no sense inside somehow?...
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0answers
14 views

Measuring strong coupling constant

How can the strong coupling constant be measured?
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0answers
15 views

Evaluating the radius of a spherical cavity that will make a glass cube just sink in water

A glass cube of side 5cm having spherical cavity within just sinks in water. If the specific gravity of glass is 2.5, what is radius of spherical cavity?
1
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1answer
24 views

Role of the Yukawa potential

What is the Yukawa potential converging to zero? Afaik the strong potential rises with the distance between quarks, hence, it should rise accordingly.
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0answers
12 views

Momentum of neutrino and beta particle [on hold]

In carbon-14 decay beta particles with end point energy 0.155MeV are emitted. A beta particle with 0.025MeV energy is emitted at 135 degree to the direction of motion of recoiling nucleus ,calculate ...
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1answer
40 views

Does the timeline of earth changes if Gravity exceeds 15g instead of 9.8g? [on hold]

as we present a timeline to be the 4th dimensions will the dimension changes simply changing the gravity? lets say 9.8g to 15g what will be the impact on the timeline as we represent timeline as ...
1
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1answer
22 views

Negative pressure in general relativity

Is there an intuitive way to understand what negative pressure means in general relativity in the same way as positive pressure can be thought to be kinetic energy of gas particles? Dark energy has ...

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