The gauge-theory tag has no wiki summary.
3
votes
1answer
59 views
Four-gauge-boson vertex in non-Abelian gauge theories
In Peskin & Schroeder's book page 524, the following diagram is calculated for the gauge boson self-energy in order $g^2$:
In dimensional regularization, its contribution is given by
...
4
votes
1answer
143 views
Yang-Mills instanton
How can instanton solution to Yang-Mills theory with gauge group $SU(3)$ or $SU(N)$ be obtained? For $SU(2)$ it is explained in textbooks but what about more general color gauge groups?
EDIT: How ...
2
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0answers
27 views
Is there a critical order of the Abelian gauge theory in (2+1)D
In (2+1)D spacetime, it is known that the $U(1)$ gauge theory is always confined (according to Polyakov), while the $\mathbb{Z}_2$ gauge theory can support a deconfined phase. Now consider a generic ...
2
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0answers
22 views
Holomorphic coupling as a source for gaugino condensation
On the top of page 23 of hep-th/03061119, it is pointed out that treating the holomorphic gauge coupling $\tau$ as a background (spurion) superfield allows one to think of its $F$-term, $F_\tau$ as ...
4
votes
1answer
131 views
On the Aharonov-Bohm effect, and the reality of the classical fields
As far as I can check, the Aharonov-Bohm effect is not -- contrary to what is claimed in the historical paper -- a demonstration that the vector potential $A$ has an intrinsic existence in quantum ...
3
votes
2answers
208 views
primary constraints for constrained Hamiltonian systems
I would be most thankful if you could help me clarify the setting of primary constraints for constrained Hamiltonian systems. I am reading "Classical and quantum
dynamics of constrained Hamiltonian ...
3
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0answers
50 views
Does the ensemble of effective Lagrangians in the String theory landscape mostly include gauge theories?
String theory false vacua can be described by effective Lagrangians at low energy. Is there generally a correspondence between these effective Lagrangians and SU(N) gauge theories? Or do the effective ...
6
votes
1answer
74 views
Do instantons support quantum bound states?
When one quantizes a scalar in the 1+1 dimensions in the kink background of a double well potential, one finds a spectrum that includes: (1) a zero mode corresponding to the classical particle ...
0
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1answer
143 views
Are string theories gauge theories?
The wikipedia page for String Theory lists SO(32) and E8×E8 as group symmetries of some of the string theory types, and the page on E8 says:
E8×E8 is the gauge group of one of the two types of ...
6
votes
1answer
130 views
How can a massless boson (Gluon) mediate the short range Strong Force?
I thought massless particles were mediators for long range forces such as electromagnetism and gravitation. How can the massless gluon mediate the short range strong force?
4
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0answers
40 views
The consistency conditions of constrained Hamiltonian systems
I am studying the Hamiltonian description of a constrained system. There are some questions puzzled me for days, which I have been stuck on it. From the lagrangian, we can obtain the primary ...
2
votes
1answer
94 views
Moose Models (Purpose, Examples)
A problem set for my QFT class is titled "Moose Models" and deals with the moose model for a gauge symmetry of $U(1)\times U(1)$. I was wondering if I could get an explanation of what a Moose Model ...
6
votes
1answer
247 views
Why is color conserved in QCD?
According to Noether's theorem, global invariance under $SU(N)$ leads to $N^2-1$ conserved charges. But in QCD gluons are not conserved; color is. There are N colors, not $N^2-1$ colors. Am I ...
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0answers
98 views
Weak isospin and types of weak charge
My understanding is that QCD has three color charges that are conserved as a result of global SU(3) invariance. What about SU(2) weak? Does it have two types of charges? What I'm getting at is:
U(1) ...
10
votes
2answers
348 views
Gauge invariance and diffeomorphism invariance in Chern-Simons theory
I have studied Chern-Simons (CS) theory somewhat and I am puzzled by the question of how diff. and gauge invariance in CS theory are related, e.g. in $SU(2)$ CS theory. In particular, I would like to ...
3
votes
1answer
77 views
Bianchi identity of a non-Abelian gauge theory?
How can one prove the Bianchi identity of a non-Abelian gauge theory? i.e.
$$
\epsilon_{\mu \nu \lambda \sigma}(D_{\nu}F_{\lambda \sigma})^a=0
$$
6
votes
2answers
196 views
Chern-Simons degrees of freedom
I'm currently reading the paper http://arxiv.org/abs/hep-th/9405171 by Banados. I am just getting acquainted with the details of Chern-Simons theory, and I'm hoping that someone can explain/elaborate ...
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0answers
36 views
axial and vector resonances in composite higgs models
Is there a reason to believe that the axial resonances be heavier than the vector resonances in the composite higgs models?
For instance, in http://arxiv.org/abs/0808.2071, to have zero tree level ...
0
votes
1answer
102 views
Interaction potential analysis from $\phi^4$ model
In this paper, the authors consider a real scalar field theory in $d$-dimensional flat Minkowski space-time, with the action given by
$$S=\int d^d\! x ...
4
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0answers
55 views
sigma model on $S^1 \times S^3$
In arXiv:1207.3497 - 4D partition function on $S^1 \times S^3$ and 2D Yang-Mills with nonzero area, Yuji Tachikawa explains the partition function for an 4d $\mathcal{N}=2$ sigma model on $S^3 \times ...
3
votes
1answer
172 views
The theory of strings stretching between intersecting D-branes
I am trying to understand various aspects of intersecting D-branes in terms of the gauge theories on the worldvolume of the D-branes. One thing I'd like to understand is the worldvolume action for ...
6
votes
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95 views
How to perform contour integral in Nekrasov's formula
My question is technical. It is about instanton counting calculation (see this paper).
The partition function of SU(N) gauge theory with $N_f$ fundamental multiplets in k instanton background is ...
6
votes
1answer
103 views
What is the meaning of non-compactness in the context of $U(1)$ in gauge theories?
In John Preskill's review of monopoles he states
Nowadays, we have another way of understanding why electric charge is
quantized. Charge is quantized if the electromagnetic U(l)em gauge
group ...
5
votes
2answers
196 views
Why is the Yang-Mills gauge group assumed compact and semi-simple?
What is the motivation for including the compactness and semi-simplicity assumptions on the groups that one gauges to obtain Yang-Mills theories? I'd think that these hypotheses lead to physically ...
5
votes
1answer
198 views
Coulomb gauge fixing and “normalizability”
The Setup
Let Greek indices be summed over $0,1,\dots, d$ and Latin indices over $1,2,\dots, d$. Consider a vector potential $A_\mu$ on $\mathbb R^{d,1}$ defined to gauge transform as
$$
A_\mu\to ...
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0answers
48 views
Do Boundary Conditions depend on spin connections for gauge fields?
In the article arXiv:1206.5642, which talks about gauge fields in conical spacetime, I came across the statement in footnote 4 that the boundary conditions on the gauge field depend on the spin ...
5
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0answers
92 views
Master Field Large N limit
I would like to ask a question about the so-called ''Master Field''. As far as I understand, this represents a classical configuration in the large n limit (saddle point solution) but there is no ...
2
votes
1answer
118 views
Construction of the supersymmetric Faraday tensor
When I first learned gauge theories in my introductory quantum field theory course, I was taught that the Faraday (field-strength) tensor can be constructed by computing the commutator of the ...
5
votes
2answers
229 views
Geometrical significance of gauge invariance of the QED Lagrangian
The QED Lagrangian is invariant under
$\psi(x) \to e^{i\alpha(x)} \psi (x)$, $A_{\mu} \to A_{\mu}- \frac{1}{e}\partial_{\mu}\alpha(x)$. What is the geometric significance of this result? Also why is ...
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0answers
27 views
Good Books on Gauge Theory [duplicate]
Possible Duplicate:
Comprehensive book on group theory for physicists?
I'm having a hard time trying to get my head around the fundamentals of gauge theory. I've taken classes in QFT and ...
3
votes
1answer
189 views
Local and Global Symmetries
Could somebody point me in the direction of a mathematically rigorous definition local symmetries and global symmetries for a given (classical) field theory?
Heuristically I know that global ...
2
votes
2answers
351 views
What is the difference between a photon and a phonon?
More specifically, how does a wave-particle duality differ from a quasiparticle/collective excitation?
What makes a photon a gauge boson and a phonon a Nambu–Goldstone boson?
7
votes
1answer
251 views
Diffeomorphisms, Isometries And General Relativity
Apologies if this question is too naive, but it strikes at the heart of something that's been bothering me for a while.
Under a diffeomorphism $\phi$ we can push forward an arbitrary tensor field $F$ ...
6
votes
1answer
180 views
Introduction to Gauge Symmetries: Good, Bad or Ugly?
I'm trying to come up with a good (as in intuitive and not 'too wrong') definition of a gauge symmetry.
This is what I have right now:
A dynamical symmetry is a (differentiable) group of ...
2
votes
2answers
160 views
Is the artificial gauge field a gauge field?
The so-called artificial gauge fields are actually the Berry connection. They could be $U(1)$ or $SU(N)$ which depends on the level degeneracy.
For simplicity, let's focus on $U(1)$ artificial gauge ...
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0answers
224 views
How can two time theories be compactified to 3+1 without any Kaluza-Klein remnants
I have recently been looking into the two-time theories and the implied concepts.
For me this seems slightly hard to grasp.
How can I see the basic concept in this theory in a fundamental way based ...
8
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4answers
331 views
To which extent is general relativity a gauge theory?
In quantum mechanics, we know that a change of frame -- a gauge transform -- leaves the probability of an outcome measurement invariant (well, the square modulus of the wave-function, i.e. the ...
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0answers
42 views
Attractiveness of spin 2 gauge theories [duplicate]
Possible Duplicate:
Why is gravitation force always attractive?
I have heard that the attractiveness of gravitation is due to the fact that it is a spin 2 gauge theory. Why is this so? I ...
1
vote
1answer
145 views
observable quantities are gauge invariant?
I have a simply question, that is whether spatial velocity is gauge invariant.
It is seems that under a infinitesimal coordinate transformation the velocity is just transform as other vectors, and it ...
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0answers
161 views
About the gauge invariance of Chern-Simons' theory (in local coordinates)
I am aware of the differential form language proof of the fact that for arbitrary gauge transformations the Chern-Simons' term shifts by a WZW term (on the boundary).
But I am getting confused if ...
3
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0answers
109 views
Gauge-invariance of pole mass using Ward Identity
I am able to explicitly verify to one-loop order that pole masses are independent of the choice of gauge paramter.
But how do I use the Ward-Identity/Taylor-Slavnov identity show that the position of ...
0
votes
1answer
115 views
In a gauge theory, are two states related by a global phase transformation identified?
In a gauge theory (non-abelian for this question), I am told that two states $|\psi\rangle$ and $|\phi\rangle$ are to be identified if they are related by a gauge transformation $U(x)$
...
2
votes
1answer
95 views
Yang Mills Hamiltonian
Do you know why in the quantization of SU(2) Yang Mills Gauge Theory, it is always chosen the Weyl (temporal) gauge to derive the Hamiltonian?
Is it possible to fix another gauge?
5
votes
1answer
329 views
Faddeev-Popov ghost propagator in canonical quantization
Obtaining the propagator for the Faddeev-Popov (FP) ghosts from the path integral language is straightforward. It is simply
$$\langle T(c(x) \bar c(y))\rangle~=~\int\frac{d^4 p}{(2\pi)^4}\frac{i ...
1
vote
4answers
145 views
Cubic term in gauge theories
In ordinary classical gauge theories the term $-\frac{1}{2}\mathrm{Tr}(F_{\mu\nu}F^{\mu\nu})=-\frac{1}{4}F^a_{\mu\nu}F_a^{\mu\nu}$ in the Lagrangian is completely natural. A somehow rare term would be ...
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0answers
140 views
7 sphere, is there any physical interpretation of exotic spheres?
Basically an exotic sphere is topologically a sphere, but doesn't look like a one. Or more accurately:
homeomorphic but not diffeomorphic to the standard Euclidean n-sphere
The first exotic ...
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0answers
37 views
Taylor-Slavnov Identity in spontaneously broken gauge theories
Where can I find a list of important Taylor-Slavnov identities in Spontaneously broken gauge theories? I am looking for not just the generating functional form, but rather a list of explicit ones ...
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0answers
29 views
What is the physical meaning of the higher order structure functions in the BRST quantization of open algebras?
What is the physical meaning of the higher order structure functions in the BRST quantization of open algebras? As opposed to formal algebraic manipulations.
Thanks.
2
votes
2answers
177 views
Path integral on matrix model
I was looking at a 0-dimensional matrix model, where the variables are $N\cdot N$ Hermitean matrices. It had a gauge symmetry, e.g. $U(N)$. And in the path integral, the Faddeev-Popov trick was used. ...
2
votes
1answer
174 views
Large gauge transformations
I would like to understand what is the importance of large gauge transformations. I read that these gauge transformation cannot be deformed to the identity, but why should we care about that?
