Recent content by elduderino

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    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?
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    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
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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.
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    Degeneracy in a rectangular box

    [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.
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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...
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    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...
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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.
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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...
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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...
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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...
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    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...
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    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...
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    Noether's theorem: quantum version

    To what I have thought about it, yes and yes.
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    How do I subscribe to individual subforums on my google reader?

    I am trying to subscribe to individual sub-forums, for example, Physics Forums > Science Education > Homework & Coursework Questions> Advanced Physics But I am not able to do it. The reader just gives me the feeds of the entire website. Anyone has any clues what I could do, preferably in...
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    Scattering States vs. Bound States

    First, examine the time independent schrodinger 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...
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