Gauge theory Definition and 94 Threads

In the presence of a magnetic field with vector potential \vec A and an electric field, the Schrodinger equation for a charged particle with charge q and mass m becomes: \frac{1}{2m} (\frac{\hbar}{i} \vec \nabla-q\vec A)^2 \psi =(E-q \phi)\psi Another fact is that, Schrodinger equation...

Hi, I have a question in Srednicki's QFT textbook. In p.460 section 75(about Chiral gauge theory), it says "In spinor electrodynamics, the fact that the vector potential is odd under charge conjugation implies that the sum of these diagrams(exact 3photon vertex at one-loop) must vanish."...

Could anyone give a really quick explanation for gauge theory to me? Or a link, or a book is perfectly fine. I just completely don't understand SU symmetry breaking and etc. etc. I also have a question, is everyone who lurks around here a college professor on quantum physics or something...

Hi, while I'm going deeper in my SR/GR knowledge, having LQG unrderstanding as main goal ( my QM background and maths is a bit stronger than GR's one, til now ) I came across some interesting youtube lectures about Gauge theory of Gravitation...

Hello, Brief context to this question: I'm an economics student and I've recently seen a lecture by phycisist-turned-economist Eric Weinstein, who says that "neoclassical economics is a naturally occurring gauge theory". In response to this, I tried to find out about group theory and gauge...

From the first moments that I read about gauge theories, till now, after years, They are still a mystery to me.Maybe that's because I never had someone explaining them to me or never actually seen any real calculation regarding them, but I think I should be able to understand them now. Anyway...

I've come across countless sources that gauge fix SU(N) Yang-Mills fields using the typical U(1) gauges (e.g. Lorenz gauge, coulomb gauge, temporal gauge, etc). However, I can't find a single one where they prove that this gauge fixing is valid for all field configurations... I've tried to...

I understand that writing the E-H action in terms of tetrads makes evident GR is a gauge theory. IOW general covariance/diffeomorphism invariance in GR is a form of gauge invariance. However unlike other gauge theories(for instance EM dependence on Minkowski spacetime), this gauge invariance in...

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...

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...

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!

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} =...

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?

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?

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...

I have a project this year called "Is gravity a gauge theory?". From my understanding, it is. But I was wondering if someone could quickly explain to me the way/ways of showing this and perhaps some papers or books that would be particularly useful. Thanks.

http://online.kitp.ucsb.edu/online/qcdscat11/ You can see it happening in these talks. For now it's just d=4 N=4 super-Yang-Mills and d=4 N=8 supergravity, but there is every reason to think that the relationships being discovered there will be extended (in more complex forms) to other gauge...

Hi, Hope some one can help me with a problem I am working on: It involves working out: \frac{\delta L}{\delta A_\nu} of the following Lagrangian: L=\frac{1}{4}F_{\mu\nu}F^{\mu\nu} + \frac{1}{2} (D_{\mu} \Psi)^{*} D^{\mu}\Psi The solutions show that this is equal to: \frac{\delta...

Is the following formula correct? Suppose we work in a 4D Euclidean space for a certain gauge theory, \int d^4x~ \text{tr}\Big(D_i(\phi X_i )\Big) = \oint d^3S_i~ \text{tr}(\phi X_i) and, \int d^4x~\partial_j \text{tr}(\phi F_{mn}\epsilon_{mnij}) = \oint d^2S_j~ \text{tr}(\phi...

Is it possible to produce massive composite particles from a non abelian gauge theory of massless fermions? I know that if the quarks were massless, the pions will be massless too (goldstone bosons). But what about baryons? Will they be also massless? If so, can we make a general statement that...

I'm hoping there will be some comment on this new paper of Kirill Krasnov http://arxiv.org/abs/1101.4788 Gravity as a diffeomorphism invariant gauge theory Kirill Krasnov 24 pages (Submitted on 25 Jan 2011) "A general diffeomorphism invariant SU(2) gauge theory is a gravity theory with two...

Hi all, Just a question i was wondering about. We know that in electrodynamics the Lagrangian is invariant under a gauge transformation of the potential, and this is equivalent to the law of conservation of charge. Concerning relativity, what is the quantity that is conserved and are the...

Question on Witten's paper: "Perturbative Gauge Theory As A String Theory..." Hi guys, I have a question regarding formula 2.12 of Witten's paper hep-th/0312171 "Perturbative Gauge Theory As A String Theory In Twistor Space". He just states this formula but i don't really understand his...

I'm applying to grad school this year and I'm thinking I might be interested in exploring lattice gauge theory. Honestly, I don't know very much about the subject but it sounds very interesting to me. Does anybody know which schools have lattice gauge theory and which schools are really good...

Peter Woit ("Not Even Wrong" blog) reported today on two recent talks by Edward Witten which are available video online. Here is the link to Woit's blog, which gives an brief overview of what the talks are about. http://www.math.columbia.edu/~woit/wordpress/?p=3107 In case anyone is...

Recently I hear there's lots of research on higher spin gauge theories. I know nothing about it, so I'll ask some naive questions. How is Weinberg-Witten no-go theorem which forbids spins greater than 1 bypassed in these theories? Is the topic related to string theory? Thanks for answer.

Does someone know something about this theory? Is it popular, or just accepted by very few people? What is the flaw or defect of this theory? Has it been ruled out by some observations or experiments? Thx.

Hello, Could somebody please point me out introductory online book/paper with which I can start understanding gauge theory and how to find out about the progress in the areas Thx

http://arxiv.org/abs/1004.0693 Gravity as the Square of Gauge Theory Zvi Bern, Tristan Dennen, Yu-tin Huang, Michael Kiermaier (Submitted on 5 Apr 2010) We explore consequences of the recently discovered duality between color and kinematics, which states that kinematic numerators in a...

Suppose I have a gauge potential A_{\mu\nu}, which is totally antisymmetric, if, say, the theory is in 6 dimensions, so that there are 6\times5/2 = 15 degrees of freedom. For the action S = \int d^6x F_{\mu\nu\rho}F^{\mu\nu\rho} , where F_{\mu\nu\rho}\equiv \partial_\mu A_{\nu\rho} +...

http://golem.ph.utexas.edu/category/2010/03/an_invitation_to_higher_gauge.html#c032039

Homework Statement Show that it is always possible to pick a gauge so V' = 0. Homework Equations We weren't given any, but I've been working with: (a)\vec{E} + \frac{\partial\vec{A}}{\partial{t}} = -\nabla{V} (b)\vec{A'} = \vec{A} + \nabla{\psi} (where \psi is a scalar function) (c)V' =...

how is general relativity cast as a gauge theory?

Hi: What's a gauge theory?, Is it just some kind of theory invariant with respect to some transformation? (like electrodynamics where the potentials are not sigle valued) and what is the importance of gauge theories in particle physics? Thanks

I'm an undergraduate in physics, I'm on my 2nd year. I have to write this assignment about the Higgs particle and gauge theory. There are quite some things that are unclear to me however. Since I'm only on my second year I don't know a lot of deep math like group theory, just basic stuff. I know...

It occurred to me that I hadn't seen GR developed as a gauge theory in the same way QCD/electroweak are. Are there any technical obstacles, or is it reasonably straightforward? And if it is well known, can someone please point me to a reference? Thanks.

I do not see why it is not. I believe relativity is a gauge theory, due to the spin connection on a so(1,3) principal bundle. I have heard some people say it is not a gauge theory. Why do they say this, are they just stupid or what?

So I'm trying to read through Baez&Muniain's "Gauge Fields, Knots and Gravity". One thing I was particularly hoping to get out of this was a specific understanding of what a "holonomy group" is. In the relevant section (p. 231-233 in the version I'm looking at), Baez& describe a holonomy by...

GR as a Gauge theory ?? don't know if this is true or not, but i have been reading books by ROvelli (LQG) or 'Gauge theories' the question is could we study Gravity as the set of functions A_{\mu}^{I}(x) Then we write the Einstein Lagrangian (or similar) as: \mathcal L =...

Marcus! Surely, I’m not the only one reading the links that you provide! http://arxiv.org/PS_cache/arxiv/pdf/0706/0706.1534v1.pdf Coupling gauge theory to spinfoam 3d quantum gravity Simone Speziale June 11, 2007 Note: The Acknowledgments: The author is particularly grateful to Carlo...

Many seem to argue it is but Steven Weinstein argues in his paper http://philsci-archive.pitt.edu/archive/00000834/00/gr_gauge.pdf" it is not. He argues that the diffeomorphism invariance of GR is more restrictive than gauge invariance since in the case of diffeomorphism invariance the...

First, I am not the greatest at LaTex so if I screw this post up I will go back and try to clarify. I will skip some steps, but get the general gist of everything. Ok, I am following the derivation of the resistive strain gauge equations starting from the basic form of resistance of a wire...

http://arxiv.org/abs/math.DG/0511710 Higher Gauge Theory John C. Baez, Urs Schreiber 10 figures Differential Geometry; Category Theory "Just as gauge theory describes the parallel transport of point particles using connections on bundles, higher gauge theory describes the parallel...

what do these terms have to do with each other? yang mills gauge theory 't hooft instanton