Symmetry Definition and 907 Threads

I don't know if it is the correct sub-forum, if I choose wrong then feel free to move the thread. I was listening to a talk today using DCSB. I think I could get a glimpse on some other parts of the talk and found some ideas intriguing. I would like to understand them better, but I cannot...

Hi, As per Clariut's theorem, if the derivatives of a function up to the high order are continuous at (a,b), then we can apply mixed derivatives. I am looking at http://en.wikipedia.org/wiki/Symmetry_of_second_derivatives and I cannot understand in the example for non-symmetry, why the...

I still wonder about this. A simple results of this equation is: If a charge has a velocity in the positive y direction [v = (0,1,0)] and it accelerates in the positive x direction (it curls) then there will be a magnetic field in the positive z direction. There will be no magnetic field...

Hi, I was wondering about the U(1)_A problem. The Lagrangian exhibits a (in the limit of vanishing quark masses) U(1)_A symmetry but due to the chiral anomaly, the current J_5^{\mu} is not conserved: \partial_{\mu}J_5^{\mu} = G\tilde{G} + 2i\bar{u}\gamma_5 u +... The G\tilde{G} term...

I have the next decay: B^0 \rightarrow D^+ e^- \nu_e The question is: employ CP symmetry on the particles in this process, what reaction would you get? and what would happen if CP symmetry breaks? Now if I employ CP symmetry I get: B^0 \rightarrow D^- e^+ \bar{\nu_e} But in my...

Homework Statement I am given a symmetric tensor A, meaning A^{\mu\nu}=A^{\nu\mu} and I am given an asymmetric tensor B, meaning B_{\mu\nu}=-B_{\nu\mu} Now I need to show that: A^{\mu\nu}B_{\mu\nu}=0 0) Homework Equations We know that an asymmetric tensor can be written as...

Is the Lagrangian of the neutral Proca field \mathcal{L}=-\frac{1}{16\pi}\left(F^{\mu\nu}F_{\mu\nu}-2m^2 A_{\mu} A^{\mu}\right) symmetric? And How to make sure whether it's symmetric.

Excerpted from an article by U. of Hawaii Physics Professor, Victor J. Stenger: "As has been known for seventy years, quantum phenomena depend not only on the initial conditions of an experimental setup but also on the final conditions. This observation already signals that the quantum...

Homework Statement Derive an expression for the moment of inertia about the axis of symmetry for a cylinder of mass M , length L and radius a, where the mass density decreases as a function of distance from the axis as 1/r Homework Equations The Attempt at a Solution 1) am i...

Hello everybody, that´s a simple question: I have a symmetry problem to analisys using Structural Mechanic on Ansys Workbench. I´ve applied a Symmetry function on Design Modeler. Can I visualize the result on the whole geometry? Thank´s in advance

The total electric field is given as Etotal = E0 +E1 +E2 +E3 Where E0 is the applied field, E1 is the depolarization, E2 is caused by polarization of a hypothetical sphere while E3 is the one dependent on lattice geometry... How come E3 is zero for cubic symmetry? Can I picture this as...

Homework Statement Given f(x), find an expression to check whether f(x) has rotational symmetry about any arbitrary point (h, v).Homework Equations If f(x) = f(-x) then the function is symmetrical about the y-axis. If f(x) = -f(-x) then the function is point-rotational about the origin.The...

Hi... I have studied the standard model and know that spontaneous symmetry breaking by a vev breaks SU(2)xU(1) to a U(1). How do we know to what group a vev will break the original group? I have heard of Dynkin diagrams. Are they only for continuous groups? Is there any other method for...

This is not homework. I have problem deriving the solution for cylinder with radial symmetry given: \nabla^2U(\rho,z)=R''+\frac{1}{\rho}R'+\frac{Z''}{Z}=0 Which give \rho^2 R''+ \rho R' -k\rho^2 R=0 \hbox { and } Z''+kZ=0 With given boundary conditions U(\rho,0) = U(\rho,h) =0...

I have come across a problem I am trying to understand, and hoping someone here has some insight. Basically, when writing down different solutions for an EM field from given sources, there seems to be a problem from the standpoint of time symmetry. From my understanding, if you reverse time, the...

Hello all, This is not a homework problem. Just to understand the two doubly degenerate mode of D4h symmetry i wanted to make sample calculation. Pt in the middle of a square formed by 4 Cl atoms. PtCl4 has square planar structure (AB4) molecule. 1. What is the whole charge of PtCl4 ? Is this -2...

Hello all, In a D4h symmetry group we have 5(3)-6=9 normal mode of vibrations. Normally in books they show only 7. Because 2 of that 7 doubly degenerate Eu modes. And i know the how it vibrates (picture shown in book). But does anyone know how their degenerate partners vibrate ? Is there some...

Hey! I am stuck at a passage in the QFT book of Peskin & Schroeder and I need your help :) It is about page 698, last break. The sentence is: "At long wavelength, the Goldstone bosons become infinitesimal symmetry rotations of the vacuum, Q |0> , where Q is the global charge associated...

Hi I am struggling to get my head fully around the conjugacy classes of D5. Everywhere I have looked seems to say that there are 4 irreducible representations of D5 which implies that there are 4 conjugacy classes. However, when examining the symmetry of the pentagon I am only able to see 3...

For a graph of any function, one of following conditions is said to exist so as for it to be symmetric: a graph is symmetric about y-axis if along with a point (x,y) a point (-x, y) exists. a graph is symmetric about x-axis if along with a point (x,y) a point (x, -y) exists. a graph is...

Can anyone help me how the high symmetry points in the bandstructure are named. I know a few rules which are as listed below: * Points (and lines) inside the Brillouin zone are denoted with Greek letters. * Points on the surface of the Brillouin zone with Roman letters. * The...

So I've found the strangest thing with oreos and milk. I have a glass of milk and when I just toss an oreo inside of it and let it sit, even for the longest time, it doesn't really get all saturated with milk and delicious. However, when I hold the oreo while dipping it in the milk, it becomes...

Homework Statement Take the Schrodinger equation for a point particle in a field: i\hbar \frac{\partial \Psi}{\partial t} = \frac{1}{2m}(-i\hbar\nabla - q\vec{A})^2\Psi + q\phi\Psi I'm supposed to determine what the transformation for Psi is that corresponds to the gauge transformation...

I've been thinking about how the requirement of anti-symmetry of the wavefunction is introduced in multi-electron problems and I am left puzzled over some aspects of it. Various types of symmetry come automatically in classical physics. If you are studying water flowing in a cylindrical...

given a symmetrical truss, loaded with an assymetrical load, i can divide this truss into 2 separate symmetrical trusses, one with a symmetrical load and one with an antisymmetrical load, then to solve the truss i can solve half of each of these 2 trusses and add/subtract results accordingly...

I know people have looked into what it would mean if photons had a mass. But what would it mean if gluons had a mass? ie. if there was a small violation of SU(3) symmetry. In other words, how do we know (experimentally) there is SU(3) symmetry?

Hello, Now that there's only one week left until the LHC starts working on the collisions, I think it's a good idea for me to ease my mind and ask how will they observe superparticles and discern them from the SM particles.

Homework Statement Using indical notation, prove that a 2nd order symmetric tensor D remains symmetric when transformed into any other coordinate system. Homework Equations Tensor law of transformation (2nd order): D'_{pq} = a_{pr}a_{qs}D_{rs} The Attempt at a Solution I think I'm...

Homework Statement I have to find the area moment of inertia about an axis 33 to the x-axis http://img227.imageshack.us/img227/2392/shape.jpg Homework Equations I_\phi=\frac{1}{2}(I_{xx}+I_{yy})+\frac{1}{2}(I{xx}-I_{yy})cos2\phi - I_{xy}sin2\phi The Attempt at a Solution I found...

Homework Statement Using indical notation, prove that D retains it's symmetry when transformed into any other coordinate system, i.e. D'_{pq} = D'_{qp} (where D is a symmetric 2nd order tensor) Homework Equations D'_{pq} = a_{pr}a_{qs}D_{rs} (law of transformation for 2nd order tensors)...

With all kinds of low energy superpartner particles floating around, do we get the same types of atoms and molecules that build up our world? Will the periodic table of elements be larger or smaller? Is this world friendly to the evolution of intelligent life?

Is there any book or source avaliable that clearly shows the point symmetry operation with matrix representations?

What is the symmetry group of manifold which models our world in general relativity. In special relativity this group is Poincare group. Its elements preserve standard lorentz inner product. What structure is preserved by elements of symmetry group in GR (sygnature of metric, maybe sth else?).

Sorry I am spamming the forum, but I have yet another question on Feynman diagrams - Please see attached picture. Apparently the symmetry factor for this FD is 1 - I am trying to understand why. My notes explain that "the symmetry factor is 1 because: φ(x1) contracts to φ(y1) in 4 different...

This is a general question, I was reading my textbook and this statement confuses me: "The symmetry of the electric field must match the symmetry of the charge distribution" this is said regarding symmetry in relation to GAuss' law. I do not understand what they mean by symmetry of charge...

Symmetry breaking "domain walls" The only "spontaneously broken symmetry" that I can easily visualize, is cooling down a ferromagnetic material and having the spins randomly choose a direction to align. Since the choice is random, different regions will usually choose different directions...

OK, having some trouble wrapping my head around this so would appreciate some clarification. Let us say I had a long, thin wall metal tube of radius R with a uniform charge per unit length. Would there be some magnitude of E of the electric field at a radial distance of R/2? I understand...

1. could anyone give sort of a qualititative explanation of how symmetry and irreducible representation are related in the context of molecular spectroscopy? like why is it so useful to count how many symmetries a molecule has and what does it have to do with irreducible represenations and...

Hey guys, I've been doing a lot of reading on quantum mechanics lately and realized immediately that i am not going to get far without first understanding the meanings of lie groups, SU groups etc. Now I've loked at wiki but unfortunately wiki is not a very good tool for learning math, it's more...

my question is , given the Group G of symmetries for the equation x^{4} + a^{2}=0 for some 'a' Real valued i see this equation is invariant under the changes x \rightarrow -x x \rightarrow ix x \rightarrow -ix x \rightarrow -x x \rightarrow i^{1/2}x x...

It is my understanding that in string theory, loop quantum gravity, the 'asymptotic safety' approach, and in semiclassical quantum gravity, local Poincare symmetry is exact. But there are things like DSR (does the D stand for Deformed, or Doubly? I've heard people say it either way), which...

When deriving the conserved quantity in the case of space-time symmetry, a line in my notes goes from: \int{dt.(1+\epsilon\dot{\xi}).L[q(t+\epsilon\xi)+{\delta}q(t+\epsilon\xi)]} - \int{dt.L[q(t)+{\delta}q(t)]} where L is the Lagrangian and \xi is a function of time and both integrals are...

In short, if we consider the group of symmetries of a regular octahedron, we see (or at least, the author of "Groups, Graphs and Trees" saw...) that the group is isomoprhic to Z2\otimesZ2\otimesZ2\otimesS3 - particularly since if we break up the vertices into 3 groups of front-back, top-bottom...

Not getting symmetry at all. I keep reading over and looking for various materials on the subject, but I still can not seem to fully grasp it. Could someone explain what symmetry means in quantum mechanics in a way that a new learner can grasp? This question also applies to super-symmetry...

but ultra important in quantum physics? i can see it is important in quantum physics but i can not see why it is less important in classical physics.

In superconductivity, Meissner effect describes the expulsion of magnetic field. Could this be described as a breaking of the electromagnetic force in the way that the higgs field breaks electro-weak force?

How does one express mathematically the fact that: if we complex-conjugated everything (switch i to -i (j to -j etc. in hypercomplex numbers) in all the definitions, theorems, functions, variables, exercises, jokes ;-)) in the mathematical literature the statements would still be true?

I am struggling for some time to understand the concept of broken symmetry. As I come more from the solid state side than from high energy physics. My problem is the following: I understand, how e.g. the rotational symmetry in a ferromagnet is broken. The magnetic moment is observable and I can...

The Lagrangian is given by, \sum_{a=1}^N \left[(\partial^{\mu}\phi_{a}^{\ast})(\partial_{\mu}\phi_{a})-m^{2}\phi_{a}^{\ast}\phi_{a}\right]. Is the symmetry SO(2N), SU(N) or U(N)? It seemed quite obvious to me and some of my friends that such theory has an SO(2N) symmetry. If we view...

how to prove that the symmetry group of a regular polygon has only 1 and 2 dim irreducible representations?