Symmetry Definition and 907 Threads

\mathcal{L} = \frac{1}{2}(\partial_{\mu}\underline{\phi}).(\partial^{\mu}\underline{\phi}) + \frac{1}{2}\mu^{2}\underline{\phi}.\underline{\phi} - \frac{\lambda}{4}(\underline{\phi}.\underline{\phi})^{2} + \bar{\psi}(i\gamma . \partial )\phi - g\bar{\psi}(\phi_{1}+i\gamma^{5}\phi_{2})\psi...

Dear PF, Could anyone help me to understand the following issue: I don't understand the formation of Goldston bosons in chiral symmmetry breaking. Namely - suppose there is only fermion fields Lagrangian and due to some reasons the fermion field obteins VEV - <0|psi^bar psi|0> is non...

I often have this problem when reading physics books (the kind I can understand) where, because I'm only in High school math, the author explains only in analogies, and the analogies sometimes don't make logical sense. I'm reading Steven Weinberg's "Dreams of a Final Theory" and I got to the...

Hello. I've got a QFT final tomorrow, and one question is still bothering me. Consider two lagrangians. The first one is L = \frac{1}{2} D_{\mu} \vec{\phi}.D^{\mu} \vec{\phi} + \frac{m^{2}}{2} \vec{\phi}.\vec{\phi} - \frac{\lambda}{4} \left(\vec{\phi}.\vec{\phi}\right)^{2} The second...

Hi, i am confused on this question: Wigner proved that a symmetry is represented by either a linear unitary operator or an anti-linear anti-unitary operator. But does it's inverse right? i.e. Does any linear unitary operator stand for a symmetry transformation? It seems to be right, as a...

Having watched with interest the "progress" in theory since my retirement, I have come to the conclusion that it well may be in the state that Ptolemaic astromical theory was in its heyday. That is to say since the circle was the most 'perfect' figure everything else could be understood using...

Would forces act with the same symmetry in 4D as it does in 3D?

Dear PF, Could anyone advise me where I can find the following book: Dynamical symmetry breaking in quantum field theories - Miransky, V.A. Is itt possible to download from somewhere? Cheers George

Right I have been given the following problem and cannot resolve it. I have had an attempt but without much success. Could anyone help me with this exercise, please? A cyclic hexagon is a hexagon whose vertices all lie on the circumference of a circle. The vertices of a cyclic hexagon are...

Right I have been asked to identify the elements of a full symmetry group of a pentagon and give the order of each element? I have found the elements which I have marked as I, R (Rotation of 72 degrees), R2 (Rotation of 144 degrees), R3 (Rotation of 216 degrees), R4 (Rotation of 288 degrees)...

Sorry I am not sure if I should put this thread here.. looks like I am going to be told off by the boss :frown: Anyway, here is my question in a triangle ABC, AB = AC and D is a point on AC such that AD = DB = BC. Find the size of the angle BAD? Find the angles of triangle ABC? Just need...

In a triangle ABC, AB = AC and AD = DB = BC. Find the size of the angle BAD? Find the angles of triangle ABC? Just need a few hints to get this problem started please? :redface:

8. Let f : R^3 → R a function all whose first order partial derivatives are continuous and such that f(0, 1, 1) = 0, f_x(0, 1, 1) = 1, f_y(0, 1, 1) = 2, f_z(0, 1, 1) = 3. Find lim t-->0 f(t2, cosh t, et) f(t, cos t, cosh t) 9. Let f : R2 → R such that f(x, y) = f(y,−x) for all (x, y) ∈ R2, and...

New issue of http://www.symmetrymagazine.org/cms/?pid=1000183" is about the Snowmass meeting to work toward designing the International Linear Collider. Other stories: http://www.symmetrymagazine.org/cms/?pid=1000191": An experiment with polarized electrons probed the strength and asymmetry...

How is the electroweak symmetry actually broken in the standard model ? Please could you explain the idea to me. Thanks Roger.

y=-2\tan (3x+\pi) +3 state the following period = \frac {\pi} {3} y-intercept=3 Range = {y: yER} Domain= {x: ?} Symmetry? Vertical Asymptotes? Zeros? Can someone please tell me how to figure out what is left there are so many zeroes and i can't read them off of my...

Hi can someone please help me get started on the following question? Q. Let A be a real invertible n * n matrix. Show that \left\langle {\mathop x\limits^ \to ,\mathop y\limits^ \to } \right\rangle \equiv \mathop y\limits^ \to A^T A\mathop x\limits^ \to = \left( {A\mathop y\limits^ \to...

Hi all, Reintroducing myself, this is the David who was active here many years ago when Greg started up physics forums. I've been off buried in other projects for some years but hope to become active again here. Some people in this forum might find the magazine I run useful and...

Does EM force obey the conservation of strangeness like the strong force?

Does anybody have an enough simple example and explanation of spontaneous breaking symmetry in quantum mechanics? When does the process of breaking take place? After or before some small perturbation appears?

I would much appreciate if anyone could give me some tips/referencess on Dynamical Symmetry Breaking. Namely detailed referrence on Namby Jona-lasinio model of mass for particles.

Here's 2 more I am having difficulty with, I'll show you what I came up with or what I think the answer is 1. 2x = 3y^2 (sqrt 2x/3) = 3y/3 y = sqrt (2x/3) Symmetric to the X-axis 2. x^2 + 4y^2=16 not symmetric to any axis

I'm looking at how you find E in a Nonconducting sheet. It all makes sense until the last part. Visualize a thin, infinite, nonconducting heet with a uniform positive surface charge density \delta . A sheet of thin plastic wrap, uniformily charged on one side, can serve as a simple model...

The potential function: V(x_r,y_r,\theta_r,x_g,y_g,\theta_g,x_b,y_b,\theta_b) = 3 - exp(-x_r^2-y_r^2)(cos(\theta_r) + \sqrt{3}sin(\theta_r)) - exp(-x_g^2-y_g^2)(cos(\theta_g) + \sqrt{3}sin(\theta_g)) - exp(-x_b^2-y_b^2)(cos(\theta_b) + \sqrt{3}sin(\theta_b)) where the nine variables...

You sacrifice mass to create energy (energy is just mass with a velocity), and the faster mass moves (relativity) the more massive the mass gets, is there some sort of significance to that? I hate riddles.

This is my (limited) understanding of particle physics: In particle physics gauge symmetries play an important role. To allow for massive gauge bosons this symmetry is broken. The theory of weak interactions can be derived from a local SU(2) symmetry, and quantumchromodynamics from a local SU(3)...

Determine the restrictions on the constants A, C and E such that the following equation is a parabola with a vertical axis of symmetry. Ax^2+Cy^2+x+Ey=0 a) A=0, C cannot=0, E cannot=0 b) A=0, C cannot=0, E=0 c) A cannot=0, C=0, E=0 d) A cannot=0, C=0, E cannot=0 i know that A cannot=0...

I'm currently taking a symmetry analysis course. It is really interesting. I would recommend it to any math major or anyone interested in ODE's and PDE'S. I am enjoying it very much.

Mass-energy equivalence is fundamental in relativity, but it seems like energy and momentum are also different aspects of the same thing. They've each got very important conservation laws. In SR, the space coordinates of the four-momentum give the momentum while the time coordinate gives...

Hi Could someone point me to a comprehensive resource (either book or website or both) which explains the method of symmetry for the solution of simple resistive electric circuits? Thanks and cheers Vivek

Greetings--a few further questions and thoughts from Peskin and Schroeder An Introduction to Quantum Field Theory. (I'll do my best to keep the discussion self-contained, but I'll provide references as well.) Is there an easy way to produce Feynman diagrams in LaTeX? (Maybe Daniel has a...

Symmetry in crystal structures- please help! Hi there, I was hoping someone here could help explain a few things about crystal symmetry to me cos it hs me so confused (we've been doing crystals for 2 weeks and things up til now have been ok, I'm just getting myself muddled as usual!). The...

Problem : A long coaxial cable carries a uniform volume charge density \rho on the inner cylinder (radius a ), and a uniform surface charge density on the outer cylindrical shell (radius b ). The surface charge is negative and of just the right magnitude so that the cable as a whole is...

What are they? "A fundamental property of the natural world that is of supreme importance for physics. It has two components: rotational symmetry, and boost symmetry." :confused:

I'm considering how the 2nd law of thermodynamics (2LT) might necessitate quantum mechanics. For it would seem that QM effects always consist of a superposition of states. Each state has a particular structure, and there is a number of these states that must be in quantum mechanical...

Quarks can't exist in isolation and the electric charge on quarks can't exist in isolation from the electric charges of other quarks either.The electric charge of leptons like the electron can exist in isolation.Isn't electromagnetism showing a kind of asymmetry here: symmetry could be restored...

How does a non-abelian gauge symmetry lead to asymptotic freedom for quarks?

Experiment shows that many physical quantities are conserved and that the associated conservation laws can be linked to symmetries. However it seems strange that general relativity is a theory built from principles of symmetry and yet energy might not be conserved in general relativity.Surely...

could someone explain this

How does symmetry breaking occur?

If I take a large mass such as the sun and change its negative electric charges (half the total number of charges) into positive charges, so all electric charges are positive, and I transform the electric force so that like charges attract, the charges would be behaving like masses.If I take the...

What are the properties of "space" at the Planck length? http://physicsweb.org/article/world/17/3/7

Is the amount of information taken in by a Blackhole, proportional to the amount given out?

I reading a great book called Symmetry by Roy McWeeny. For those that love Dover Books this one's a gem. Anyway, I have a question. How do you partiton a particular group into distinct classes? The author was discussing the symmetry group C3v the rotation, and reflection of a...

Problem 1. Consider the equation y=a(x-r_1)(x+r_2) Write the equation of the axis of symmetry.

What is this symmetry breaking process I keep hearing about?

Hello, I hope you don't mind this elementary question, but I got stuck with it this evening: GSW state in their equ. (2.1.44) that a combined reparametrisation and a Weyl scaling obeying d^aA^b + d^bA^a = Gamma n^ab don't change the choosen gauge h^ab=n^ab. Now I tried to proof this. The...

Perfect Symmetry Heinz R. Pagels wrote about it. I have read it. But I don’t remember enough to say for sure that what I will discuss in the following is not just echoes of what he said. In any event, my understandings of perfect symmetry are the following. In a perfect universe...

Subtitle: Fallacy of all physical experiments If the symmetry of time is broken then all physical experimentations are fallacious. Take one experiment, a bias is unavoidably embedded into it. This bias is time. All experiments are always done in looking backward in the time direction. A...

If there are three spatial dimensions, why is there only one time dimension? Why can't there be three temporal dimensions parallel to the spatial ones. If there are, perhaps this is what they would resemble. The fourth dimension could be temporal linear - the easiest way to view time...