Gauge Definition and 641 Threads

Whether traveling at c in the form of radiation and carrying energy in the process or to exert the force propagated by force fields, the mass-less gauge bosons cannot go faster than c and even the gravitational force which is caused by the space-time curvature or hypothetically gravitons cannot...

HAI I am SYED , i am doing my project using strain gauges. Problem description: I have 4 strain gauges bonded to an octagonal ring. The strain gauge i am using is METAL FOIL TYPE , GF(gauge factor) -2 and 320ohm resistance. The strain gauge has two terminals ,my question is (1) Can anyone...

I'm currently attempting to explain the concept of Gauge Symmetry to a friend. Copied and pasted pretty much directly from MathIM, (And the same applies for any other potential field, such as gravitational potential.) Would this be correct? I've tried explaining Gauge Symmetry multiple...

Hey there guys! So we know that in linearized GR we work with small perturbations \gamma _{ab} of the background flat minkowski metric. In deriving the linearized field equations the quantity \bar{\gamma _{ab}} = \gamma _{ab} - \frac{1}{2}\eta _{ab}\gamma is usually defined, where \gamma =...

http://arxiv.org/abs/1204.3672 Gauge Theory of Gravity and Spacetime Friedrich W. Hehl (U Cologne and U of Missouri, Columbia) (Submitted on 17 Apr 2012) The advent of general relativity settled it once and for all that a theory of spacetime is inextricably linked to the theory of gravity...

Hello, just had a quick silly question about the coulomb gauge here, though I guess it applies for gauge transformations in general. The problem is, I'm concerned about my gauge choice not being consistent with the equations of motion. For example, suppose I'm working with a nonrelativistic...

I've been reading up on gauge theory and it isn't easy. Can someone give me an easy summary of its fundamental scope and postulates without too much math. It seems really important insofar as it defines itself as something of a "parent" theory to most of the leading cosmological models of the...

These are notes I made when I was studying the subject 20 years ago. They seem fine considering that I was student then. I believe they can be useful for those who are studying Yang-Mills and other related material. Sam

This is an exciting development in LQG. They have a proposal for how to generalize the ideas of spin network and spin foam so that the network vertices are made of chunks of noncommutative space instead of ordinary space. I'd be glad if anybody who's looked at the paper and wants to volunteer...

It is said that : electrodynamics is a gauge theory for U(1) gauge group . what is its physical concept? Mathematically it mean that the field is invariant under transformation under components of U(1) group, that we can show them with e^{i\theta} and we can consider them as a phase angle . so...

I've read that gauge invariance leads to a fundamental phenomenon.What is that? Thanks

I have a motor that I am using, and I need to know what gauge wire to use to connect to the motor. I've looked all over online, but haven't found anything that can tell me a formula or anything to use to figure this out. The motor is 24VDC and draws 50A max, and would be running about 15...

For free EM field: L=-\frac{1}{4}FabFab Then the stress-energy tensor is given by: Tmn=-Fml∂vAl+\frac{1}{4}gmnFabFab The author then redefines Tmn - he adds ∂lΩlmn to it, where Ωlmn=-Ωmln. The redefined tensor is: Tmn=-FmlFvl+gmv\frac{1}{4}FabFab It is gauge invariant and still satisfies...

I'm curious if anybody else has felt this/ what they did to deal with it. I starting going to school with the intention of working in very theoretical physics, something along the lines of M-Theory possibly. I'm in my third year double majoring in physics and mathematics. Unfortunately, I've...

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...

Hi, my question is, if there is an interpretation for electromagnetic gauge fields, whose components are imaginary. This would lead to an imaginary magnetic field... Does anything like this exist? Or is it forbidden ny some first principal arguments? Thank you in advance for every input! Melvin

Hi all, I'm taking graduate level QM I and trying to wrap my head around the notion of gauge symmetry. For some reason I've struggled with this concept more than others. I don't really have a specific question; I'm more looking to see if someone has a succinct explanation of the relevant...

Homework Statement Homework Equations I am learning QFT, and I am confused of such transformations. For example, first, in these equations, especially the one that defines the transformation of A(x), whether should the partial derivative acts on U(or U-1), or just take U as a constant...

I'm currently working through Griffith's book Introduction to Elementary Particles, and studying the chapters on gauge theories. From classical E&M, I understand what we mean by a gauge transformation and why the Lagrangian must be invariant under such a transformation, but what I don't...

How to arrive at Lorenz gauge condition? http://en.wikipedia.org/wiki/Lorenz_gauge_condition I know it's used to simplify the 2 partial differential equations of the potentials, but why can we put such a restriction on the potentials? Doesn't that restriction restrict the possible electrical...

Homework Statement Confirm that the retarded potentials satisfy the Lorentz gauge condition. Homework Equations \vec{A}(\vec{r}, t) = \frac{\mu_{0}}{4\pi}\int\frac{\vec{J}(\vec{r'},t_{r})}{R}d\tau' V(\vec{r}, t) = \frac{1}{4\pi\epsilon_{0}}\int\frac{\rho(\vec{r'},t_{r})}{R}d\tau' Where...

1) Since Wigner it is well known that for massless particles of spin s the physical states are labelled by helicity h = ±s; other states are absent. So e.g. for photons the physical states are labelled by |kμ, h> with kμkμ = 0 and h = ±1 and we have two d.o.f. 2) For gauge theories with...

My book has introduced the idea of gauge invariance in terms of classical electrodynamics (attached file). However, I am not sure I completely understand how it works. On the one hand they use a lot of time on specifying how you can add to the vector potential the gradient of any scalar, whilst...

hi everyone, I have been trying to understand gauge theory. I am familiar with the Noether's theorem applied in the context of simpler textbook cases like poincare invariant Lagrangians. This is my question: Are there Noether currents corresponding to the local gauge symmetries too and would...

My understanding is that for electrons, there is a standard argument that the electromagnetic interaction between them is required, not optional. Since they're identical particles, we should be able to take the wavefunction of two electrons and mix up their identities by any amount we like, and...

Homework Statement I'm working on some things to do with linearized gravitational radiation and I'm trying to justify the claim that in the Lorenz gauge, where \partial_{\nu}\bar{h}^{\mu\nu}=0 (1.1), we are able to impose the additional conditions A_{\alpha}^{\alpha}=0 (1.2) and...

I'm reading wald page 85, and he defines a stress-energy tensor for the linearized gravitational field. he mentions that it not gauge invariant as a problem. but isn't that a general property of any tensor (except scalars). so any stress-energy tensor will not be gauge invariant (change of...

Could someone explain what a gauge theory is, both in general and how it applies to physics? Please try to keep definitions relatively simple, even though the topic is exceedingly complicated. Examples are also greatly appreciated. Thanks!

I have a few strain gauges that are going onto the suspension of a race bike. I've never installed these things before. While I have found a lot of information on installing them, I am having a hard time finding many adhesive and chemical options. It seems a lot of them are non-permanent, or...

Hello everyone, I read on Wikipedia that a lot of the properties of photons are explained by them being the quanta of an abelian gauge field (link). Does anyone happen to have a good source on this? I haven't learned anything about gauge theories yet, so I'm looking for an introductory text...

I have read 2 arguments that a gauge symmetry cannot be spontaneously broken. 1. Wen's textbook says a gauge symmetry is a by definition a "do nothing" transformation, so it cannot be broken. 2. Elitzur's theorem, eg.http://arxiv.org/abs/hep-ph/9810302v1 The first argument seems sound...

Internal symmetries of the SM -U(1), SU(2), SU(3)- are usually said to belong to abstract spaces unrelated to spacetime symmetries, have there been many attempts to relate internal symmetries to spacetime symmetries, and if so how far have they gotten?

Once I've asked here why you physicist use Gauge theories with such confidence and the overall answer was "because it works". This probably is true but perhaps is also a bit disappointing to me because I was looking something more fundamental. I've recently thought of something that may be the...

What is means that unintegrated parton distributions and matrix elements are supposed to be gauge invariant??

I know what gauge invariance is, but I'm not sure what gauge covariance is. Is it that a given field has a gauge covariant derivative? And under which circumstances do we get a field that is gauge invariant but not gauge covariant? And I would appreciate an example (other than the one...

[a]1. Homework Statement [/b] I thought it would be easier to post a picture since this way the drawing can be seen. I'm having a hard time deciding what angles to use with the relevant equations, see below. Homework Equations I know that: Ex' =...

The title says it all. I've seen an example worked out, and there mass was given to a gauge boson specifically. Also, I wouldn't know why the Higgs boson would want to give mass to the fermions, since they already have mass in the Yang-Mills theories; it's only the gauge bosons that initially...

Homework Statement The .png file attached shows a simple rain gauge where rain water is collected through a funnel of 25cm diameter. As water flows through the sides of the vessel and it fills the vessel it exerts an upward force on the bottom surface of the float. This force is transmitted...

Hello, I've been reading about the weak interaction. Basically, the weak interaction couples to particles that are left-handed, and we introduce the electron-electron neutrino as a (left-handed) SU(2) doublet. So, the gauge bosons (W+, W-, and Z) transform SU(2) triplet. Am I right...

Is it okay to classify the angular degree of freedom of a point on a circle as a gauge degree of freedom? (i). One can add 2Pi to angle without changing the position of point. (ii). U(1) symmetry exp (i theta)

Find a gauge transformation which maps the Coulomb gauge to the Lorentz gauge?

I'm a freshmen Physics major interested in knowing whether I should continue on with my major. I've read enough to know that with an IQ of 120, basically anything is achievable given enough work. I am confident that I posses the drive to carry on with the major but I don't want to get half-way...

good day! i was asked to solve for gauge pressure, pg1, using the combined Boyle's and Charle's Law, (pg1V1)T1=(pg2V2)T2 where V is the volume of gas and T is the temperature (in °C). now here's my question, we know that in computing for absolute pressure we need to convert the...

I find I'm biased towards heavy things. I realize this is unreasonable, as a heavier object will not always be of better quality, but I still find that I prefer a heftier object even they wouldn't necessarily benefit from it. Here are some examples of some things I prefer to be heavy: bed...

In the Lorenz gauge, the Maxwell equations reduce to four inhomogenous wave equations, with the charge density acting as the source for V, and the current density for A. For now, just take a static charge distribution -- say, a point charge at the origin. It is well known that a static...

Vibrations of a motor (40Hz) cause noise on the signal of a strain gauge that monitors load on a cantilever that measures periodic load changes at the rate of 1/minute. Design a filter that reduces the signal caused by the vibrations by 90%. I thought about a low pass filter that has a cut...

If only left handed fields couple in the weak force, and we can boost to a frame that changes left handed fields to right handed ones, how can that theory be relativistically invariant? thanks for the help!

Something is totally not making sense. In a complex scalar field theory, I have two field degrees of freedom, which I parametrize in polar field coordinates: \phi = \rho e^{i\theta}/\sqrt{2}, where \rho and \theta are real-valued; and its Lagrangian takes the form: \mathcal{L} =...

I'm really getting frustrated right now, as I am unable to reproduce the two-point gauge-field correlation function (i.e. propagator) as derived from the path integral in an R_\xi gauge using operators from canonical quantization. I believe the polarization 4-vectors of the gauge field ought to...

I am reading Mukhanov's 'Physical Foundations of Cosmology'. He claims that in the minimal SU(5) model, CP violation of a heavy SU(5) gauge boson X decay arises at the tenth order of perturbation theory. Is that correct? The tenth order perturbation theory would lead to a very complicated...