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| visits | member for | 2 years, 6 months |
| seen | 15 hours ago | |
| stats | profile views | 138 |
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May 13 |
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Lagrangian of electromagnetic tensor in light cone coordinates? @kernel_panic: It's hard to tell what you're asking. You're saying you have the Lagrangian in light cone coordinates and would like to get to cartesian coordinates? If you add the formulas you have and describe the problem better, maybe someone could reopen the question. |
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May 13 |
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Caveats when using event-by-event reweightings? Hmm, I'll write up something or look for a reference when I have time. |
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May 13 |
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Caveats when using event-by-event reweightings? (Seems you need 50 reputition to comment...) I was asking about the most general case, since this has many uses: Fixing MC, estimating BGs from data, estimating trigger effects without simulating the trigger, .... You give every event a different weight, and make a certain distribution $y$ match perfectly - but have no predictive power there anymode, since data=BG per construction. You hope that in a somewhat correlated distribution $x$ (maybe with a different selection) you now have a better modelling of the BG, but you'll be able to discern the signal, in the simplest case a bump. |
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May 12 |
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Gravity in other dimensions than 3 and stable orbits I wonder what happens if one just uses a different potental, so that one still has $F \propto 1/r^2$ even in higher dimensions? |
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May 12 |
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Caveats when using event-by-event reweightings? Say your interested in the dilepton invariant mass, so $y=M_{\ell\ell}$. You believe the angle between leptons is not well modeled, so you correct the $\varphi_{\ell\ell}$ MC distribution ($x$). You would do that in bins of $\varphi$, and you have one factor for each bin. One may determine the factor in a sideband, but applies it to all events. You seem to be thinking about normalizing to the Upsilon peak (~10 GeV), however in the case I mean the total normalization often doesn't change. (By the way, you're answer would better be a comment. We should move this discussion there.) |
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Apr 30 |
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How to calculate Riemann and Ricci tensors for a sphere? I'm not sure, can't you just read off the $g_{ij}$, since the differentials are not mixed? For example $g_{\theta\theta} = R^2 \sin^2 \varphi$. I forgot why one is allowed to do that though... |
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Apr 23 |
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Why does Hydrogen molar heat capacity reach 7/2 R? @Georg: I found it in need of an explanation that the 7th degree of freedom is really a separate DOF. Some simple arguments suggest otherwise: Say #6 is the wiggling, or $\dot p$ of the HO, and #7 is the motion of the center of mass, or $\dot x$. Then a) one variable is determined by the other through the HO DGL, thus they are not independent and b) isn't the movement of the center just a translation? |
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Apr 20 |
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How to determine predicted CP violation for a given SUSY point? Thanks. I have some negative mass parameters at the GUT scale (e.g. $M2$), but not negative squared masses, so I don't believe I have complex parameters - at least it was not my intention to introduce them. I was just told in passing by a colleague "Negative mass parameters? That's bad, you'll have too much CP violation!", although he couldn't tell me how exactly, or where he got that. |
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Feb 27 |
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Local $U(1)$ gauge invariance of QED @Nivalth: Thanks a lot, but you didn't have to accept it if it didn't help you. Qmechanic and twistor59 also deserve some credit, but unfortunately you don't get points for comments. |
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Feb 3 |
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What constitutes an observation/measurement in QM? As far as I understand, decoherence is objective, so no, two observers can't disagree. They can disagree over wheter a system is in a pure or a mixed state. Maybe my use of 'observer' is confusing here. I don't mean something deep like different frames of reference, just that different people (experimentators) have different incomplete knowlege, and that is expressed through their density operators / mixed states. Its like statistical mechanics, but QM. |
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Jan 1 |
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What is the origin of flavor? @DavidZaslavsky: Actually, I am asking the same question again. Let me justify it: The first time around, the question was misunderstood by everyone, probably because I wasn't clear enough. I wanted to correct the question, but then the (otherwise fine) answers didn't match anymore, and I was asked to open a new topic with my actual question. I guess the best thing would be to reformulate the other question to match it's answers (I'll be glad if you have any suggestions on how), and to reopen this as my actual intended question. |
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Dec 9 |
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To which extent is general relativity a gauge theory? @namewhere: No, what I meant was more along the lines of what Murod Abdukhakimov posted, namely that the metric connection shows up in the covariant derivative in the same way as the gauge field would. |
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Dec 9 |
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To which extent is general relativity a gauge theory? I faintly remember that there is a nice way to think about GR as a gauge theory (or gauge theories as geometry), and it had to do with viewing the Levi-Civita connection as a gauge field. Unfortunately I don't know enough GR to write down the argument. |
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Dec 7 |
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Expressions for canonical partition function and probabilities $p(E_i)$ If your asking questions related to your homework, you should include a bit more on what you already tried and where exactly you're stuck. Try to show some effort, people don't like doing the work for you :-). If you just need the definitions, look here: en.wikipedia.org/wiki/…, it should be easy to solve then. |
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Dec 7 |
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How do I calculate the probability that the oscillator is in a certain state using partition function? Hi abcXYZ, and welcome to Physics.SE! If you want to, you can use LaTeX code in your question to make the formulas more readable: \$ x^2 \$ becomes $ x^2 $ |
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Dec 6 |
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What is the origin of flavor? @dmckee: I want to know how people are trying to explain the origin of flavor. i.e. the conserved thing that makes muons different from electrons. Can it be a broken symmetry? Substructure? That's what I tried to ask both times. However, the other question was universally misinterpreted as something like "why three generations? (how do we know the fact, and what phenomena depend on it?)". |
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Dec 6 |
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Origin of lepton/quark generations? @Anixx: I didn't mean to ask about the number of generations. I know that answer, besides, it was already handled before here: physics.stackexchange.com/q/2051/825 . I opened a new, clarified question here: physics.stackexchange.com/q/46097/825 |
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Dec 6 |
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What is the origin of flavor? @AndreHolzner: Right. It seems that flavor is something fundamental and real, and thus a better theory might explain it. "Oh, that's a manifestation of the XYZ symmetry.". It might as well go away as a fundamental concept, like nuclear isospin, when a new theory comes along. I'm just looking for either kind of theory here. Some brilliant theorist must have thought of some crazy theory to explain this, they always do :-) |
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Dec 6 |
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Origin of lepton/quark generations? @user1504 OK, a second try :-) physics.stackexchange.com/questions/46097/… . Should we change this question to match its answers better? |
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Dec 6 |
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Origin of lepton/quark generations? Well, I explicity asked for current theories explaining the "generation" phenomenon, and I explicitly said I wasn't interested where the number "3" comes from. I'm surprized this got so misinterpreted... but you're probably right |
