Symmetry Definition and 967 Threads

For instance,how to systematically derive the equns 2.2 & 2.5 given a Hamiltonian on the article below?; arxiv.org/pdf/0904.2771.pdf .

Recently I saw this YouTube video from Veritassium about CPT -Symmetry: In this video an experiment of Prof. Chien-Shiung Wu is presented, which has proven that parity is not symmetric, by observing the emmition of electrons from Co60 atoms with synchronised spin. After thinking about this...

Will translation parallel to x-axis work ? Else please suggest the symmetry? And does symmetry here refer to the symmetry of the sheet which causes the symmetry of the field or something else? Please be kind to help.

Hello, Today I found this paper and this one where P.W. Anderson says that there is no broken symmetry in ferromagnetism because the ground state is an eigenstate of the spin rotation operator. And so we don't have in this system Goldstone's mode for example. But I thought spin waves were...

{a} P = identity Matrix w/ -1 on diagonals {b} eigenvalues = +/- 1

1.) The rule for the global ##SO(3)## transformation of the gauge vector field is ##A^i_{\mu} \to \omega_{ij}A^j_{\mu}## for ##\omega \in SO(3)##. The proof is by direct calculation. First, if ##A^i_{\mu} \to \omega_{ij}A^j_{\mu}## then ##F^i_{\mu \nu} \to \omega_{ij}F^j_{\mu\nu}##, so...

When we are talking about Bloch's theorem and also the tight-binding approximation, we can use them to help finding eigenstates of a system. However, I am so confused how to apply it in this case (below is my homework) and don't even know how to start it... All I understand about the Bloch's...

In supersymmetry, are there corresponding antimatter particles to the Susy sparticles similar to the corresponding standard model antimatter particles, e.g., antiselectron, etc.?

Symmetry transformations in physics can be either passive or active. Symmetries in field theory can be either global or local. But only the local ones, the so called gauge symmetries, are fundamental. Except that local transformations cannot be active (despite the fact that diffeomorphisms are...

After countless google searches, I decided to ask the experts. The multiverse idea seems to be popular among physicists, but the idea of a mirror universe seems much more plausible. Like quantum theory, it’s symmetrical. For every quantum fluctuation in our universe, there would be an equal and...

Hi Pf I read that the accelerated Unruh observer is in a thermal bath of particles. For him the mean value of his occupation number N of the inertial vacuum V0 is not null. <V0 N V0> is greater than 0. He is not in his vacuum V'. Suppose that he travels with a box. he cools it and leaves it...

I know that for the infalling observer the horizon is a fake singularity that can be removed via the Eddington-Finkelstein co-ordinates but wouldn't the classic Swartsheild co-ordinates still apply for the outside observer? So, while for the infaller it takes a finite time, the outside...

As I understand it for every symmetry there is associated a conserved quantity - so for time symmetry there is energy conservation. I understand as well that charge conservation is associated with a 'mathematical' local symmetry - something turning in a mathematical space at a point so to...

Hello! When using a Jordan-Wigner-mapping or parity-mapping to map the hydrogen molecule \mathrm{H}_2 with two electrons and 4 spin-orbitals to 4 qubits, it is possible to reduce the number of qubits down to two [1,2,3]. The reason is apparently that the molecule has a discrete...

For an infinite system of coupled oscillators of identical mass and spring constant k. The matrix equation of motion is \ddot{X}=M^{-1}KX The eigenvectors of the solutions are those of the translation operator (since the translation operator and M^{-1}K commute). My question is, for the...

Naively there is a conflict between CPT symmetry being at heart of fundamental physics models like QFT, and 2nd law of thermodynamics: saying that entropy grows toward future. Is there really a conflict here - so is physics symmetric or not? How to understand it? Personally I disagree with that...

https://arxiv.org/abs/2009.14613 A group-theorist's perspective on symmetry groups in physics Robert Arnott Wilson [Submitted on 29 Sep 2020 (v1), last revised 12 Nov 2020 (this version, v3)] R.A. Wilson (physics blog) worked on finite simple groups such as the famous "Monster". He writes...

I’m reading Lancaster & Blundell, Quantum field theory for the gifted amateur (even tho I”m only an amateur...) and have a problem with their explanation of symmetry breaking from page 242. They start with this Lagrangian: ## \mathcal{L} = (\partial_{\mu} \psi^{\dagger} - iq...

I am trying to get a foothold on QFT using several books (Lancaster & Blundell, Klauber, Schwichtenberg, Jeevanjee), but sometimes have trouble seeing the forest for all the trees. My problem concerns the equation of QED in the form $$ \mathcal{L}_{Dirac+Proca+int} = \bar{\Psi} ( i \gamma_{\mu}...

Untill now i have only been able to derive the equations of motion for this lagrangian when the field $$\phi$$ in the Euler-Lagrange equation is the covariant field $$A_{\nu}$$, which came out to be : $$-M^2A^{\nu} = \partial^{\mu}\partial_{\mu}A^{\nu}$$ I have seen examples based on the...

In some models of the beginning of the universe, like for example in chaotic inflation, space would stop expanding in some points, creating Hubble volumes that could experience different spontaneous symmetry breaking, which would result in different properties, such as different physical...

I see that this procedure helps to get rid of the two extra degrees of freedom (due to the scalar and longitudinal photons) one firstly encounters while writing the electromagnetic field theory in a Lorentz-covariant way; it indeed shows that modifying the allowed admixtures of longitudinal and...

Hi! This is a very very noob question, but I am starting to get into particle physics and I don't understand the application of crossing symmetry in the inverse beta decay. Crossing symmetry says (from Griffiths) that, in a reaction "any of these particles can be 'crossed' over to the other...

In some experiments of a complex physical mathematical system, we found some symmetry phenomenon, very similar as symmetry breaking phenomenon, say, as translatable sysmmetry etc. These symmetry (breaking) phenomenon occurs in most of the parts of the system or some parts of the system. Can you...

I recently encountered mirror symmetry method of solving circuits and by it solving circuits became very easy but problem I am facing with it is that I can't figure out logic behind it. For example if we try to simplify this circuit Then we say that if ##I## current flows from Point A to C then...

Is it possible to derive laws of Newtonian gravity from some symmetries?

Some rotational quantum states are not allowed for a rotating particle. At quantum level, these "forbidden" quantum states is based on the requirement of the total wavefunction being either symmetrical or anti-symmetrical, depending on whether the particle is a fermion or boson. The particle's...

I'm watching Sean Carroll's video on symmetry [relevant section at around 8:05] He talks about 120 degree rotations of triangles that leave them invariant. Then he proceeds to talk about flipping them with an interesting (at least to me) remark - "there's nothing that says I'm confined to...

I'm a bit confused about the condition given in the description of the symmetry transformation of the filed. Usually, given any symmetry transformation ##x^\mu \mapsto \bar{x}^\mu##, we require $$\bar\phi (\bar x) = \phi(x),$$ i.e. we want the transformed field at the transformed coordinates to...

Hello! This questions might not make sense and I am sorry if that is the case (I am asking from a QM class perspective). I am a bit confused about the idea of spontaneously symmetry breaking (SSB), from the point of view of QM. I am talking here about the energy plot looking like a mexican hat...

I'm trying to understand the precise reason we claim that a value being conserved means that the system in question is invariant under the corresponding symmetry transformation. Take parity for example. If the parity operator satisfies the commutation relation ##[P, H] = 0## for a given...

How can i know the resulting orbit of is symmetric about two turning points? Where m, l is constant. V is function of r u = 1/r and It is in polar coordinates. We could show that varying theta from 0 to -θ will be the same if we vary 0 to Θ, but i don't know where to start

I try to justify time-reversal symmetry in a very simple classical problem; Free Fall. The position, ##x##, and the velocity, ##v## are obtained versus time from the equation ##-g=\ddot x##. So, if we consider the primary conditions as ##t_0,x_0,v_0## it is clear that...

As we all know, for the reference frame S' and S of relative motion, according to Lorentz transformation, we can get As we all know, for the reference frame S' and S of relative motion, according to Lorentz transformation, we can get As we all know, for the reference frame S' and S of relative...

The equations of motions for a closed system consisting of ##N## particles are: $$m_i \vec x_i'' = \sum_{j \neq i}^N \vec F(\vec x_i, \vec x_i', \vec x_j, \vec x_j')$$ $$ i = 1,..., N$$ Now if we impose the requirement that this closed system be symmetric under Galilean transformations, do we...

Hello, My question is simple. I have read that isotropic biaxial strain does not lower C2 symmetry, but no proof whatsoever was provided. I would like to know if it is actually true and have a solid proof. If someone can provide it, that would be wonderful. But also explaining me how to start...

Many times when i ask about test theories of SR, i am reminded by forum members, that equipment sensitivity, is equivalent to producing more extreme physical values. For example, you don't necessarily have to go faster in speed, in order to have a better measurement of time dilation, if you have...

A standard example consider a capacitor whose parallel plates have a circular shape, of radius R, so that the system has a cylindrical symmetry. The magnetic field at a given distance r from the common axis of the plates is calculated via Ampere's law: \oint_\gamma {\mathbf B} \cdot d{\mathbf...

Hi. Over the years I've read LOT of "popular science" (i.e. non-textbook) books on entanglement, and on the explanations / objections / arguments Einsten, Bohr, Bohm and others had that still remain today. There's one aspect which never seems to get covered in these books and I wondered if...

Hello, I would like to find a mathematical demonstration of this problem. While I have always used it, I could never prove it. Given a charge or current distribution with axial symmetry the electric and magnetic dipole moment are null: (electric dipole moment) (magnetic dipole moment)and...

Would it be correct to represent the energy of massless particles before electroweak symmetry breaking as ##E = cp##, just as we do with photons post-symmetry breaking?

Hey! :o Let $F\subseteq \mathbb{R}^2$. A map $\pi:\mathbb{R}^2\rightarrow \mathbb{R}$ is called symmetry map of $F$, if $\pi(F)=F$. A symmetry map of $F$ is a map where the figures $F$ and $\pi (F)$ are congruent. Let $\pi_1:\mathbb{R}^2\rightarrow \mathbb{R}^2$, $x\mapsto \begin{pmatrix}0...

Hi folks! Help me out. Can someone explain what gauge symmetry is? Does it have something to do with the phase angle of the wave function. Any input would be appreciated! If you wanted to let me know the difference between a "local" and a "global" theory I would not object! Thanks a lot.

Browsing via the origin of SR topic below I noticed that nobody mentioned a magic word "symmetry". My opinion is that mathematical symmetries are if not fundamental to physical world then at least they sit very close to God, so to speak. By other words it is hard to come up with something more...

Every kinds of hadrons exist in three versions: normal , mions and tauons.Mion version of electron has mass about 100MeV and has the same quant characteristics as electron. I've read that in mion radiation normal objects become small (mion orbits are about 200times lesser than by electrons).What...

Hi folks! Help me out. I read that each conservation law is required to have an associated symmetry. What happens to this symmetry when something like "pair production" happens (that seems to violate mass-energy conservation for a small amount of time). What happens to the associated...

The definition of a circle is the set of all points equidistant in 2 dimensions from another, center, point.Construct now in 2 dimensions a set of all points, no two equidistant from another, "center," point.One possible construction is an infinite radial line.Another possibility is where...

Although we often frame physics in terms of a Cartesian symmetry, spherical symmetry is predominant, if not universal in our cosmos. Cubic symmetric crystals are the expression of one mode of many resonances possible for spherical atomic orbitals. In physics, 90oangles are little more...

Can anyone please give me a small but presice explanation of symmetry?Thanx