Symmetry Definition and 907 Threads

Ive tried to search around for what Bose-symmetry is, but I can't seem to find any definition. Can someone here provide me with a definition of bose symmetry?

In an N-channel mosfet, for example, can the roles of the Drain and Source be reversed such that the FET turns on with positive VGD? Will this threshold be the same as the specified one for VGS?

Homework Statement A lamina occupies the region inside the circle x2+y2=2y but outside the circle x2+y2=1. Find the center of mass if the density at any point is inversely proportional to its distance from the origin. Here is the solution...

Hello assume I sample signal between Transmiter to Reciver T->R Is the chanell respone would be the same to R->T also? especially I wonder about knife difraction effect ( Fresnel zone )

Hi. Question: Sketch f(x) = \sqrt{1 - x} + \sqrt{3 + x} On this test question from calculus, I got full marks for my answer. But I'm posting in this forum because I'd like to know how to analyze the symmetry of this function (posted below), which I actually didn't notice until I read the...

is it true to say that any molecule having a centre of symmetry will have the symmetric stretching IR inactive? thanks!

Hi, I'm going to quote a lot of a book so that I can get some help, brace yourselves... First, \phi_{a} is my field with a=0,1 as internal components and my lagrangian is L=\frac{1}{2}\partial_{\mu}\phi_a \partial^\mu \phi_a +\frac{1}{2}\mu^2 \phi_a \phi_a +\frac{1}{4}\lambda (\phi_a...

Hello, I working through my notes on Nother's theorem and invariance under translation. I don't understand how they get expression 7.3, from the line before 7.3 (see attachment). Can anyone explain. Thanks.

I am lost and confused. I have been on the same problem for 2 hours. I know all the formulas, but I'm not doing something right...

Heck, I don't even know if this is true. Intuition seems to suggest that it is but I know of no way to prove it. In general I don't know of any way to rigorously determine axes of symmetry. And I am having trouble finding anything about this, so any links are appreciated.

How to prove that wave function at \Gamma point can always be a real function? I know it is not true for general k point, but for \Gamma and other high symmetry point like X, is there a simple proof? Thanks!

Why stress tensor must be symmetric?

I was wondering about a system, specifically quantum, though classical solutions are still welcome, which was resisting all applications of Noether's Theorem, and related techniques. If a system is invariant under a switch from E→-E AND m→-m, then what are the conserved quantities (in analogy to...

Quick question (I think anyway) I'm currently trying to solve a problem that essentially is asking for me to find the final velocity of an electron that is traveling between a cathode and an anode of potential difference 300. At half the distance to the anode can I assume by symmetry that it...

Hello, I am trying to shortly explain how the Yukowa potential breaks symmetry in weak interactions. I would like to use the mexican hat potential as a specific example. Unfortunately Wikipedia does not go very in depth or explain it very well. Link. Any help on understanding the collapse of...

Homework Statement Show that Gij = Gji using the Riemann tensor identity (below) Homework Equations Gij = Rij - 1/2(gijR) Rabcd + Rbcad + Rcabd = 0 R = gmrRmr Rmr = Rmnrn The Attempt at a Solution I have tried to put the Ricci tensor and Ricci scalar (from the Gij...

Just a quick question about notation really here. In neutrino oscillation we can calculate a probability of an oscillation occurring between two flavour eigenstates - invariably denoted P(\nu_{\alpha} \rightarrow \nu_{\beta}) . I've got some confusion about what happens to this when we apply...

Given that the Classification Theorem says that every finite simple group is isomorphic to one of 4 broad categories of (specific) finite simple groups, does this mean that any conceivable symmetric: i) 2D form; or ii) 3D object is also isomorphic to one of these 4 categories. Otherwise...

Homework Statement It's example 3.8 in the Griffiths book in case someone has it. Basically the problem involves a uncharged metal sphere in a uniform field in the +z direction. Naturally, there will be induced positive charges on top and negative charges at the bottom. The question asks for...

Hi everyone, While reading about the BHZ model used to describe HgTe quantum well topological insulators, I read at many places that the effective Hamiltonian (which is a 4 x 4 matrix) can be written in block diagonal form and the lower 2x2 block can be derived from upper 2x2 block as...

Given the complete classification of finite simple groups, can one say that the number of all conceivable 2D/3D symmetrical geometric objects/arrangement is limited? Is spatial symmetry limited in our 3D world? IH

If matter composed of quarks of positive charge, and anti-quarks have negative charge, why do we call electrons particles of matter rather than anti-matter? Is it possible that the matter-antimatter symmetry problem exists because we are actually calling something that is a particle of...

The singularity theorems apply to situations away from exact symmetry ... away from Schwarzschild solution or Friedmann solutions for example. There are a number of accounts of the singularity theorems but none addressing the problem of proving a 'trapped set' still persists after slight...

What symmetry of nature yields the conservation of electric charge?

Symmetry, Groups, Algebras, Commutators, Conserved Quantities OK, maybe this is asking too much, hopefully not. I'm trying to understand the connection between all of these constructions. I wonder if a summary about these interrelationship can be given. If I understand what I'm reading, there...

This is in the introduction of the lecture notes I am using to study group theory: "An object is symmetric or has symmetry if there is an operation (e.g. a rotation, reflection or translation) s.t. the object looks the same after the operation as it did originally. An equilateral triangle is...

Steve Carlip says this [back in 2007], here,: http://www.2physics.com/2007/06/symmetries-horizons-and-black-hole.html"...Until fairly recently, no one had a clear idea of the microscopic states responsible for black hole entropy. Today, we suffer the opposite problem: we have many...

Homework Statement Determine the orders of all the elements of the power set P(S) of a set S with symmetric difference Δ. Homework Equations The Attempt at a Solution If A,b are two elements of the power set the symmetric difference is AΔB = (A-B) U (B - A) How are we...

Hi, I have already been familiar with that exterior symmetry is the spacetime symmetry. Such kind of symmetry has been depicted by Poincare' group. Then I am still find the concept internal space/internal symmetry ambiguous. And I cannot understand why put Spin in exterior symmetry not...

Homework Statement As an example, if we find a DFT of x[n]={1,1,0,1} the result will be X(m)={3,1,-1,1} Homework Equations My Question is that as we know DFT holds symmetry property, why this answer does not void for that property?

I'm trying to figure out where symmetry breaking occurs in Feynman diagrams. I'm just free wheeling here, correct me where needed. But as I understand it, when you have a Feynman diagram where there is an interaction of one particle which decays to others, the incoming particle may obey one...

Hi All, I am trying to work through a QFT problem for independent study and I can't quite get my head around it. It is 5.16 from Tom Bank's book (http://www.nucleares.unam.mx/~Alberto/apuntes/banks.pdf) which goes as follows: "Show that charge conjugation symmetry implies that the...

The Standard Model symmetries are U(1), SU(2), and SU(3). But I'm not sure whether these are symmetries of the Action intgral or if they are symmetries of the background spacetime.

Hey, We saw in class that rotating a spin state with an angle of 2pi returns minus the state, and so it has to be rotated 4pi rad in order to return to the original state. However, we also saw that the expected value of the spin DOES return to its original value after a rotation of 2pi rad...

In a mathematical system, what similarities are there between the most and least absolute symmetries? Might Noether's theorem explain this?

Hi everyone! So we're learning about the Hydrogen atom in QM and I'm having trouble reconciling something in my head. We're looking at potentials that are only radius dependent, like the Coulomb potential. Now, I know the math. I see that we assume the wave function can be separated into the...

Homework Statement Construct a hyperboloid of one sheet whose axis of symmetry is the y-axis. Homework Equations Hyperboloid of One Sheet --> x^2 + y^2 - z^2 = c The Attempt at a Solution The relevant equation is the one given in the book and in my notes. Obviously I can have...

Please teach me this: Why is CP symmetry violated in electro-weak interaction? Is it correct that because of the mass of neutrino is zero(so that the left and righ neutrinos do not mix with each other)? Thank you very much in advance.

As I understand it the heart of gauge symmetry is that I can change the phase at different points different amounts and the Lagrangian/action is unchanged. What I am not clear on is whether the changes I can make are completely arbitrary - I can make any change I want at any point - or whether...

Here are some questions that have been puzzling me about symmetry and charge. Any answers to any of these questions would be very helpful. Thank you. What does U(1) gauge symmetry mean? Does anyone have a simple explanation? Can Maxwell's equations be derived from the premise of U(1)...

Hello, new member here. I've been fascinated reading some of the threads and decided I had to register to ask a question that's always been a bit confusing to me. From what I've learned The Big Bang theory seems the most likely explanation of the start of the universe but there's one thing in...

Why do we care about Lorentz or gauge invariance if we're going to remove the cutoff at the end. our physical answers are independent of the procedure,, why do we care about preserving the symmetry "during" the calculation? Thanks for your time!

Hi, I am reading the BRST Symmetry section of Peskin and Schroeder but I can't find anywhere why the BRST transformation for the gauge vector, \delta A_\mu^a = \varepsilon \partial_\mu c^a implies that only forward polarized states can create ghosts by applying Q, Q being define by...

when a continuous symmetry is broken, we say that the ground state is just one of the possible ground states, and there is no energy cost in moving from one to the other.. why doesn't the state keep changing with the slightest perturbation (production of goldstone boson). why don't we have a...

Please teach me this: How many conserved observations(''charges'') are there in SU(2) and SU(3) symmetries?I know that U(1) has only one charge that is electric charge. Thank you very much for your kind helping.

Please teach me this: Why Sp(N) symmetry has N(N+1)/2 generators?(QFT of Peskin and Schroeder). Thank you very much for your kind helping.

Homework Statement Show that the curve is symmetrical about the x-axis (without drawing the graph) eq of the curve is : x^2 + 4y^2 = 1 also show that the curve is symmetric about the y axis Homework Equations The Attempt at a Solution To prove that the curve was symmetric abou...

Hi, If I have the Lagrangian L=i\chi^{\dagger\alpha i}\bar{\sigma}^{\mu}(D_{\mu})_{\alpha}^{\beta}\chi_{\beta i}+i\xi^{\dagger}_{\bar{i}\alpha}\bar{\sigma}^{\mu}(\bar{D}_{\mu})^{\alpha}_{\beta}\xi^{\beta i}-1/4 F^{a\mu\nu}F_{\mu\nu}^{a} where \alpha,\beta are colour indices, and i=1,2 is a...

I can only assume it is, if a Higgs can be found anyway. I learned about hysteresis in certain physical processes. I don't have the math to guess nor Google skills to find a clear answer. If it were, would a sufficiently large and hot enough black hole be in danger of losing its mass terms...

Hi, Can anyone explain the difference between axisymmetric and cyclic symmetry boundary conditions? Isn't it the same i.e. bith cyclic symmetry and axisymmetric?