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After reviewing the more than half dozen questions on the DCQE here, this doesn't seem to have been asked or answered directly - if I've missed this piece in one...
Asked on 11/05/2020 by JPattarini
5 answerLet's say we have a massless QED theory with a Lagrangian begin{equation}L=ibar{psi}not{D}psi-frac{1}{4}F_{munu}F^{munu}end{equation} The symmetric energy-momentum tensor is begin{equation}Theta^{munu}=frac{1}{2}bar{psi}Big{gamma^mu D^nu+gamma^nu D^muBig}psi-eta^{munu}ibar{psi}not{D}psi-F^{mulambda}F^nu_{ lambda}+frac{1}{4}eta^{mu nu}F^{sigmalambda}F_{sigmalambda}end{equation} The trace...
Asked on 11/05/2020
1 answerI have a theoretical black body spectrum as described by plancks law. I also have the bandpass sensitivity function for various filters. I would like to calculate a colour index...
Asked on 11/05/2020
1 answerI've read it said that decoherence is the reason we don't observe macroscopic superpositions. I find this very confusing... what exactly does it mean to observe a macroscopic superposition? Doesn't...
Asked on 11/05/2020 by Ameet Sharma
1 answerThis question is somehow related to Newton's bucket and absolute rotation concepts, but applied to a simple, tangible scenario. Let's suppose I could hover over the...
Asked on 11/04/2020 by user3566357
2 answerOne of the reasons why we can neglect electron-electron interactions in metals is the fact that their coulomb interaction is screened. I'm confused about the nature of this screening. In...
Asked on 11/04/2020 by curio
1 answerReading David Tong notes on QFT, he mentions about Gupta-Bleuler condition $$partial^{mu}A_{mu}^{+}|Psirangle=0tag{6.54},$$ which makes sure that matrix elements vanish,$$langle Psi|partial_{mu}A^{mu}|Psirangle=0.tag{6.55}$$ I also came across Ward...
Asked on 11/04/2020
1 answerDoes the resistance of a conductor depend on an inertial frame? What is the experimental and the theoretical evidences for that?...
Asked on 11/04/2020
0 answerI have given the cyclic shift operator $X(x) in mathbf{R}^{d times d}$, the generalized pauli operator, for a qudit system. This operator is defined by the action it takes...
Asked on 11/04/2020 by enco909
1 answerBasically voltage and current is gained in an amplifier which ultimately results in power and energy gain? Where does the energy come from? Does it violate law of conservation of...
Asked on 11/03/2020 by Shreyansh Pathak
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