Recent content by elduderino
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Graduate Why gluon cannot decay to quark and photon
What are flavor arguments that prevent a gluon from decaying into quark and photon, or anti-quark and photon, etc?- elduderino
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- Decay Gluon Photon Quark
- Replies: 15
- Forum: High Energy, Nuclear, Particle Physics
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Graduate Decomposing the direct sum as direct product
This is a basic question in angular momentum in quantum mechanics that I am studying. I know that \frac{1}{2}\otimes \frac{1}{2} = 1\oplus 0 What would be a strategy to proving the general statement for spin representations j\otimes s =\bigoplus_{l=|s-j|}^{|s+j|} l- elduderino
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- Direct product Direct sum Product Sum
- Replies: 2
- Forum: Quantum Physics
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Schools Withdrawing from a course at US university?
As a GTA, do I have to pay for a course if I withdraw from a course right now(>5 weeks into program). I registered late for the course and I realize that professor K teaching Quantum Mechanics 2 is not that good a teacher, and a really tough grader.- elduderino
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- Course University
- Replies: 2
- Forum: STEM Academic Advising
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Is the First Excited State of a Particle in a Rectangular Box Degenerate?
[What Tangent means] From the boundary conditions you get that n is an integer. You reject negative integers because of they give you no new information. You reject zero because that makes your wave function zero everywhere, and hence makes it non-normalizable. Only things left are n>=1.- elduderino
- Post #7
- Forum: Advanced Physics Homework Help
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Prove that dirac matrices have a vanishing trace
Not a Homework problem, but I think it belongs here. Homework Statement Consider four dirac matrices that obey M_i M_j + M_j M_i = 2 \delta_{ij} I knowing the property that Tr ABC = Tr CAB = Tr BCA show that the matrices are traceless. Homework Equations Tr MN = Tr NM The Attempt...- elduderino
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- Dirac Matrices Trace
- Replies: 1
- Forum: Advanced Physics Homework Help
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Graduate Ground state wavefunction real?
I take it you mean the solution to the time independent schordinger equation(TISE). If that is the case, then not just the ground state, any solution can be taken to be real. If psi is a solution of the TISE, then so is its complex conjugate psi* (do it and check it, this is so because the...- elduderino
- Post #5
- Forum: Quantum Physics
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Felony: Need advice for a friend
Just an FYI, most university applications have a tickbox where you check in if you have been prosecuted for any federal/state offense. So as long as he does not lie about it, there is no risk as pengwuino said.- elduderino
- Post #4
- Forum: STEM Academic Advising
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Schools Grad School Outside the US for an American
If you just want to leave the US, have you considered Canada? Good Physics places that come to mind, in continental Europe are ETH Zurich, Max Planck Institute in Germany (different for nano/theory/etc) , Utrecht in Netherlands, and some in France whose names were too French for me to remember...- elduderino
- Post #7
- Forum: STEM Academic Advising
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Programs How can one combine different areas of specialization in a PhD program?
You will join the hordes of people that spend a decade of their life as postdocs. So the motivation should be this: if you're good, and in theoretical particle physics which is a field composed entirely of outliers, being good means beyond exceptional, then you can land a job straight after your...- elduderino
- Post #7
- Forum: STEM Academic Advising
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Summer Research at CERN - Share Your Experience!
I was there 2009 summer in their official program. It was nice. I didn't get too much out of it because the best part about that program are the lecture series (which can be viewed online too btw). I had to come way before their program officially started so by the time the lectures had started...- elduderino
- Post #2
- Forum: STEM Academic Advising
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Graduate Noether's theorem: quantum version
Classically, a change in the phase space variable q_i \rightarrow q_i + \epsilon K_i(q) does not cause a first order change in the Lagrangian then it corresponds to a symmetry. The conserved quantity would be \sum_i \frac{\partial L}{\partial\dot{q_i}}K_i A commuting with the Hamiltonian...- elduderino
- Post #5
- Forum: Quantum Physics
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Graduate Non-uniform dielectric polarization
From what you've told of the solar cell, if there is no polarization on the macro scale for the ferroelectric capacitor, then there wouldn't be a discharge, just as in the solar cell. Also, in the solar cell, there's cheap energy source to cause an inhomogeneous charge distribution. Even though...- elduderino
- Post #2
- Forum: Electromagnetism
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Graduate Noether's theorem: quantum version
To what I have thought about it, yes and yes.- elduderino
- Post #2
- Forum: Quantum Physics
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What Are Scattering States and Bound States in Quantum Mechanics?
First, examine the time independent Schrödinger equation. It tells you that E should always be greater than minimum of the potential well (otherwise the function and the second derivative would have the same sign and function would no longer be normalizable). Now, think in analogy to the...- elduderino
- Post #5
- Forum: Advanced Physics Homework Help
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Graduate Any quantum analog for Betrand's theorem?
I googled your problem and this is a paper which exactly confronts your problem. (link at end of post) Bertrand's theorem: the only central forces that result in closed orbits for all bound particles are the inverse square law and Hooke’s law When looked at from a QM perspective, there's some...- elduderino
- Post #7
- Forum: Quantum Physics