Gauge Definition and 685 Threads

[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...

Hi all! Long story short, my QFT class recently covered gauge equivalence in QED, and this discussion got me thinking about more general gauge theory. I spent last weak reading about nonabelian symmetries (in the context of electroweak theory), and I like to think I now have a grasp on the...

what does it mean when they say the Gauge "Sector" of SM? what other sectors are there? Thanks

How do (offshell) QCD ward identities look like in the axial gauge? How to derive them? The standard treatment of ward identities uses BRST symmetry in the covariant gauge. I don't know where I can read about the axial gauge version of the ward identities.

i'm reading 'gauge theories in particle physics' by aitchison (http://www.ft.uam.es/personal/hernandez/QFT/Aitchison--Gauge-Theories-in-Particle-Physics-Volume-1.pdf) and i have some questions: 1. middle of page 23 right before section 1.2.3 heading: he implies because of the spectroscopy...

1) In one thread I saw that a Lagrangian that comes from a gauge theory principle is capable to generate interactions, and that would be why we should work with gauge theories. Nevertheless, any lagrangian which have multiplications of diferent fields generates interactions (or am I wrong?) 2)...

How do Holonomies or ideas of closed-loops in Gauge Theory compare to the ordinary? What is its advantage and disadvantage? And how does it scale in the plausibility rating?

Please teach me this: Why in general speaking the mass of gauge boson particle is zero(except W,Z bosons)?Because if we consider the self-energy of the bosons,we might think of the mass of gauge bosons. Thank you very much for your kind helping.

I'm just curious, in the Coulomb gauge changes made locally to the scalar and vector potential fields are propagated instantaneously, classically we wave off this problem since the potentials aren't directly observable... except they are in Aharanov-Bohm. Presumably there's something that saves...

I understand the conceptual meaning of gauge transformation which "can be broadly defined as any formal, systematic transformation of the potentials that leaves the fields invariant". I understand for example the U(1) and S(3) gauge symmetry in Gauge Theory. But what is this got to do with...

A strain-gauge bridge is made up of four resistive elements, each element having an unstrained resistance equal to R, as shown in the diagram below. When a strain is applied to the bridge elements R2 and R4 increase in resistance by an amount ΔR, whereas R1 and R3 decrease by ΔR, where...

Hello I am looking to learn about Lattice Gauge Theory. I am already understand the general theory, (that is, defining fermions and gauge fields on lattice sites and links, respectively), but am having trouble intuiting the results of such calculations. As an example, the following is a...

I have some ideas of canonical transformation is, but the ideas behind gauge transformation is still eluding me.

Hi, I have been assuming something I never took the time to prove because it is beyond my scope so to speak. But I am on the path, rest assured. My question is, is it possible to describe correctly say, the color force, using a different gauge group, regardless of the difficulty? That is...

Water poured slowly from a teapot spout can double back under the spout for a considerable distance before detaching and falling. (The water layer is held against the underside of the spout by atmospheric pressure.) In Fig. 14-23, in the water layer inside the spout, point a is at the top of the...

Homework Statement I've attached an image of a dam. The problem reads as follows: The fresh water behind a reservoir dam has depth D = 15 m. A horizontal pipe 4 cm in diameter passes through the dam at depth d = 6 m. A plug secures the pipe opening. Find the magnitude of the frictional force...

I was wondering if anyone could explain to me where the 2nd order terms in the gauge transformation h_{\mu\nu}\rightarrow h_{\mu\nu}-\xi_{\mu ,\nu}-\xi_{\nu, \mu}-\xi^{\alpha}h_{\mu\nu, \alpha}-\xi^{\alpha}_{,\mu}h_{\alpha\nu}-\xi^{\alpha}_{,\nu}h_{\mu\alpha}[/itex] come from. The...

I hear the statement that global symmetries in the boundary field theory corresponds to gauge symmetries in the bulk. 1) Is this a generic statement that is expected to hold for all holography pairs? (Maldacena states this towards the end of his first lecture at PiTP2010, which was supposed to...

Homework Statement Scientists have found evidence that Mars may once have had an ocean .5km deep. The acceleration due to gravity on Mars is 3.71m/s^2. (a) What would be the gauge pressure at the bottom of such an ocean, assuming it was freshwater? (b) To what depth would you need to go...

Homework Statement Consider a non-abelian gauge theory of SU(N) × SU(N) gauge fields coupled to N^{2} complex scalars in the (N,N^{_}) multiplet of the gauge group. In N × N matrix notations, the vector fields form two independent traceless hermitian matrices Bμ(x) =\Sigma_{a}...

Hi can someone please recommend a strain gauge to measure mass flow rate of a pneumatic conveying system. The full bridge circuit strain gauges are to be placed on a cylindrical cantilever beam with a length of roughly 160-170mm and a diameter of 36mm and made of iron. From what I have read...

Hi all , How can I find lecture notes on ArXiv ? I was looking for lecture notes on Yang-mills theories treated in the language of differential geometry but didn't succeed till now . Can some one recommend me some good resource for it?

Sorry for the newbie question. Just slap me and direct me to the right post. I did some searches but couldn't find my answer. If a fundamental particle must exert one of the fundamental forces against another fundamental particle, are the appropriate gauges boson then created by the first...

I presented a way to derive Coulomb force via the canonical mechanism. One uses Coulomb gauge \partial_i A^i = 0 derives \Delta A_0 = -4\pi\,\rho which can be inverted formally A_0 = -4\pi\,\Delta^{-1}\,\rho and calculates the interaction term in the Hamiltonian density...

I have a technical question and at the time being I can't ask it to a professor. So, I'm here: If I try to quantize the vector field in the Coulomb gauge (radiation gauge) A_0(x)=0,\quad \vec\nabla\cdot\vec A=0. by imposing the equal-time commutation relation...

In the weak field approximation, g_{\mu\nu}=\eta_{\mu\nu}+h_{\mu\nu} If we make a coordinate transformation of the form [itex]x^{\mu'}=x^{\mu}+\xi^{\mu}(x)[\itex] it changes [itex]h_{\mu\nu}[\itex] to [itex]h'_{\mu\nu}=h_{\mu\nu}+\xi_{\mu,\nu}+\xi_{\nu,\mu}+O(\xi^{2})[\itex] I...

Here and then I read gauge symmetry makes theories renormalizable. Unfortunately I could not find a satisfactory explanation why that so is. Could someone shed some light? thanks

Hi, In Electrodynamics, one often state about the gauge freedom of the magnetic potential. And so, we may choose to impose for example the Coulomb gauge, where the divergence of the potential is zero. But, isn't this only true if there exist no changing electrical field, \frac{\partial...

Homework Statement So I'm having some difficulty with my QFT assignment. I have to solve the following problem. In three spacetime dimensions (two space plus one time) an antisymmetric Lorentz tensor F^{\mu\nu} = -F^{\nu\mu} is equivalent to an axial Lorentz vector, F^{\mu\nu} =...

I Suppose, need to choose a correct wire gauge for a lighting circuit, how to calculate it. Input load 12V Battery, load (two 100 W bulb), .Please clarify.

I was trying to understand the standard calculation of Einstein's A,B coefficients in quantum theory textbooks and I came across the following difficulty. In the calculation of transition probabilities, total wavefunction is expanded into eigenstates of time-independent H_0 and the expansion...

Consider the Wilson lattice action for a Yang-Mills theory with two parameters - color N and coupling g. 1) The strong coupling expansion on the lattice is given in terms of \beta = N/g^2 . But what is the other parameter of the lattice theory? Is it N? In that case, does the \beta-expansion...

Hello all ! My question: Does fibre bundles are necessary for describing gauge invariance in electromagnetic case? Or fibre bundles uses only for describing gauge invariance in cases of weak, electroweak and strong interactions? Thanks

Hi, Don't know if anyone can help me but have a bit of confusion with Srednicki ch75 p466 just above (75.55). I understand why in non-Abelian gauge theory we get extra factors Tr(T^aT^bT^c) and so on, but I don't understand why the P_{L}\to1/2 diagrams then end up with the extra factor...

Hello everyone, I have a question about wire gauges and choosing the right one. Anyway this is related to my job. Long story short, we have systems that are powered by solar batteries(which are recharged through solar panels). Anyway these batteries supply 12V DC to various different devices...

Hello: I was under the impression that gauge symmetry was a property of the Lagrange density. Here is the Lagrangian for EM written out in its components: \begin{align*} \mathcal{L}_{EM} &= J\cdot A +\frac{1}{2}\left(B^2-E^2\right) \quad eq.~1\\ &=\rho \phi - Jx Ax - Jy Ay - Jz Az \\...