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Dear forum please help me with the following understanding: There is (are) such equipment Earth ground testers (https://www.fluke.com/en/products/electrical-testi...) - it is used to measure grounded electrical systems or to measure. Such equipment is having multiple poles that are attached to...

Dear willem2 and DaveE, Let me ask another question... "When you get far away from the conductor, it should look like the conductor had no effect. Like this:" When an initial charged (with charge +Q) plate creates an electric filed it originates from the charged surface and penetrates into...

Dear PF, I have a question regarding a conductor in electric filed. I have formulated my question in attached PDF file ... would please be so kind and advise me please... Thanks you in advance ...

Dear PF, I need to have a simple mini-camera with wire connection... (i don't want wireless transmission). if i get for example an ordinary small FPV camera...

Dear Forum Memebrs, Could you please advise if it is possible to think that in some instances the flow of fluid in P&ID diagram is similar to the flow of electrical current in circuit boards: in order to have an electric current you have to have a potential difference across two points (which...

Thanks Bill_K for you help... So is it (TT gauge) much the same as Coulomb gauge in vector field theory ? Thanks

I have a question about gauges in gravity. Symmetric tensor field in four dimensions has 10 independet components, when we want to describe massless spin-two field (graviton) we impose harmonic gauge which reduces 10 independet components to 6 and afterwards we use diff invariance and...

Dear PF... Please help me with basic question more I think more I get confused... In O(n) space there are n(n-1)/2 generators... suppose I have symmetric tensor in O(n) space, it will have n(n+1)/2 independent components... and i am building invariant potential from it (quartic polynomial...

Could you please advise me how does one get the 5.4.10 matrix in the attached page from the "MOHAPATRA R.N. UNIFICATION AND SUPERSYMMETRY.. THE FRONTIERS" or what are those epsilons... Thank you

Dear PF, Could you please advise me good detailed reference on Grand Unified Theories... especially I want to see where for example SU5 potential is composed from two Higgs representations (two Higgs fields) and how symmetry breaking (minima of potential appears for both of fields) happens...

Could you pls advise me any reference (textbook for example) where I can find how to calculate maxima minima of function of several variables... or drop a couple of lines here.. Thank you

Hi, A symmetric 4x4 matrix has 10 independent components. Let's say that matrix describes graviton h_mu_nu. In general I can bring any symmetric matrix to diagonal form, so if can and I bring my h_mu_nu matrix to diagonal form where it has only 4 independent components ... than what happens...

Dear PF, I am trying to draw some diagrams in jaxo draw, but I don't know how to assign Greek index whenever necessary, can you please advise me step by step... as i understand it is related to some "postscript" issues that i don't know how to set up ... would you be so kind and drop me a...

Dear PF, I am a little bit confused could you pls help me ... Suppose I a have a scatering or conversion of two particles via graviton propagator. Graviton propagator couples with energy-momentum tensor of matter fields. So can i assume that vertex to which graviton propagator is coupled...

Thank you Bob S for your reply... If the source is radioactive isotope then I guess only Crystal Bragg diffraction might be applicable . . . correct ?

Dear PF, Is is possible to focus somehow gamma radiation? Suppose d'like to intensify gamma rays and I want to focus it... is it possible to do it... ? Are there any materials that may "reflect" gamma rays.. to use as a "reflector" thus intensifying ... thank you

Just forgotten to mention (combination of fields) exactly the same . . . so identical field combinations in two vertex but different coupling strength . . .

Sorry if this appears a basic question, but could you pls advise me is it possible to have a two identical vertexes but with different strength coupling? I have some toy Lagrangian and when I calculate Feynman rules I get for one vertex following expression: (M1+M2)*(combination of...

Hi, In SUSY we introduce chiral superfield, vector superfield, then build some invariants and get the SUSY lagrangians which after decomposition into normal fields (F and D terms) gives us for example ordinary QED plus some other terms. And we call this SUSY-QED. I have following question...

Hi, I have a following question... Can it be that there is given some Lagrangian and instead of considering whole Lagrangian one makes its series expansion and considers only some orders of expansion? Can you bring some examples or why and when does this happen... ? Thank you

Qgravity thanks for interesting resources... wish you successful 2012

Hi, Could you pls advise me any textbooks or papers where I can find pedagogical introduction to N=2 Supersymmetry & familiarize myself... Thank you very much Best Regards

HI, We can construct vector superfield by chiral field minus anti chiral super field (example Bailin-Love page 59 expression 3.23) So does this vector superfield have a kinetic term-WW ? since the for the kinetic term we have expression 3.37 and it seems that if vector superfield is...

OK as i understand I can compress ice till it complitely turns into water... if a have an ice cube and i exert force (big force) whole ice will turn into water... but what is its compressibility when my force is not that big to turn the ice cube into water ?

Dear PF, Is ice compressible? What its compressibility... or compressibility relatively to water compressibility Thanks much

Please help me with combinatorics: I have three sets: A with elements (a1 ……..ai ) B with elements (b1 ……..bk ) C with elements (c1 ……..cj ) Pls help me to work out how many sets ABC shall I have that contain each element from sets A, B and C Thanks much

Dear all... Pls advise me how to read and understand piping drawings (process PID drawings)... I mean how does fluid flow and what process are running there. I am doing physics and I have quite good technical background. When interpreting electrical circuits we are having nodes with defind...

Nobody knows :( ...

Dear PF, I am having very heavy supersymmetric derivatives to do (and in general heavy calculations) could you advise me any software/package or something that will help me to do my calculations on computer? Thank you very much Rgds GT

Hi, Is it possible to construct chiral superfield from Vectorsuperfields and/or combinations of vector superfield and some another chiral superfield... Thanks

Silly question... ? :(

Hi, If I have a Lagrangian of complex scalar field (just U(1) local invariance). And I know that phi^star describes field with -e electric charge and phi describes field with e electric charge. How do I apply "charge issue" when I write Lagrnangian after spontaneous symmetry breaking in...

HI, Sorry if this questions should have gone to other section, but since it involves supersymmetry I posted it here. I can't resolve some exercises on supersymmetry and supergravity from Bailin/Love's book - so don't you know if there is some sort of solutions book to those exercises or...

I ve seen here some link to PBS nova website, where it were some short sketches about gravity dark matter strings etc etc... may u please remind me that link... coz I ve gone throught the forum and could not locate that thread. I went directly to Nova website and there also could not see all...

Gents, Is there such software package or something like that... when you input the lagrangian it gives you the vertecies (Feynman rules)... Thanks

Why neutrino may have magnetic moment? Even if it is massive... it is not composite and it is electrical neutral...

Hi, May you please asdvise me where in Peskin Schroeder it is described how to derive 1/r potential for electrodynamics... (I mean from quantum field point of view) Thanks

Any additional comments?

May be in other words my question will sound what are the free field vacuum fluctuations...

Since the only structure that can be constructed for free field is its propagator can we say that process of birth is real death is real but all this happens in a tiny time interval that no energy violation is detected... If there were charges for example electric of course antiparticle will do...

Hello PF, If the the interacting field (phi^4 theory or QED) vacuum corresponds to bubbles for example: photon goes into electron-positron pair and then vice versa.. etc... etc... To what does the free (non-interacting) field vacuum correspond? 10x

? :(

Could you pls advise me QFT textbooks where the Schwinger effect is described... Thanks a lot

no ideas ... :(

Hello PF :) Let me for the moment consider just <0|\varphi(y)\varphi(x)|0> as a propagator (instead of commutator of the fields)... and so in this expression evolves only <0|aa^{+}|0> part. Now my question is: 1) We can consider this expression as <0|a vector multiplied by a^{+}|0> which...

Hi, Could you please advise me any software (and location) to draw Feynam diagrams? I knew one softare Feyndraw but lost it... Thanks

Thanks Gents ...

Hi, Could u advise me please some references where the Feynman rules for graviton are derived I mean graviton-scalar graviton-graviton scattering ... in general graviton vertecies ... Thank you

Hi... Would you please advise me what does gauge fixing term do (physical point of view) ? Does it eliminate unnecessary spin components from lagrangian for example: Vector particle has two (massless case) or three (massive case) degrees of freedom. Vector itself has four, and a vector...

Help urgently needed in Mathematica Simplify Dear All, I have a very longe expression (see file attached ) of variables x, a, Lambda... etc, when I apply "Simplify" I am left only with very short expression ONLY with variable Lambda. But if in the initial expression I declare...