All Questions
Tagged with symmetry-breaking gauge-theory
90
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31
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Unitary Gauge Removing Goldstone Bosons
The Lagrangian in a spontaneously broken gauge theory at low energies looks like
$$ \frac{1}{2} m^2 ( \partial_\mu \theta - A_\mu )^2 $$
and the gauge transformations look like $\theta \rightarrow \...
- 29
5
votes
2
answers
365
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Why are there no Goldstone modes in superconductor?
Usually, the absence of Goldstone modes in a superconductor is seen as an example of the Anderson-Higgs mechanism, related to the fact that there is gauge invariance due to the electromagnetic gauge ...
- 109
3
votes
1
answer
95
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Are Higgs mechanism and SSB different phenomena?
In the Standard Model, the Higgs mechanism is associated with the Spontaneous Symmetry Breaking (SSB).
My understanding is that it is the Higgs field which breaks the $SU(2) \times U(1)$ symmetry at a ...
- 1,665
2
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0
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64
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Masses of $SU(2)$ gauge bosons
I'm currently learning quantum field theory and I'm wondering one thing.The way I understood it is that in the $SU(2)$ Yang-Mills theory, all gauge bosons have the same mass due to the spontaneous ...
- 41
1
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0
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37
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Loop Calculations of A Spontaneous Broken gauge theory with fermions
Let me first rephrase the background. Consider adding a massless fermion to the spontaneously broken $U(1)$ gauge theory through a chiral interaction:
$$
\mathcal{L}=\bar{\psi}_{L}i \gamma_{\mu}D^{\mu}...
- 81
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votes
1
answer
58
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Can we prove in general that gauge fields associated with broken generators form representations of the unbroken group?
The title is a bit ambiguous. More specifically, I'm asking:
Are all coupling between massive gauge fields (associated with broken generators) and massless gauge fields of the unbroken group are in ...
- 619
2
votes
1
answer
142
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Spontaneous Symmetry Breaking, Vacuum Degeneracy, and Goldstone Bosons applied to large gauge transformations
I am reading Strominger's lecture notes on the infrared structure of gravity and gauge theory. I am trying to understand subchapter 2.11, where the author focuses on the notions of "Spontaneous ...
- 3,982
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90
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Anderson Higgs mechanism and superconducting phase fluctuations
In the context of superconductivity, in the Anderson Higgs mechanism (see, for instance, https://doi.org/10.1119/1.5093291 (PDF), or https://doi.org/10.21468/SciPostPhysLectNotes.11 (PDF), the gauge-...
1
vote
1
answer
73
views
What is the reverse operation of gauging a global symmetry?
As far as I understand, gauging a global symmetry means taking a model with a global symmetry and transforming it into a model such that the previous symmetry group is now the gauge symmetry of your ...
0
votes
1
answer
106
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Lattice $SU(2)$ Higgs model in unitary gauge
I'm currently reading the book Quantum Fields on a Lattice by I. Montvay and G.Münster, and in section 6.1 they describe lattice actions for various higgs models. And I got confused at the moment ...
- 377
1
vote
2
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165
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Comparing "gauge theory" and "(global) spontaneous symmetry breaking"
To construct an effective field theory with spontaneously broken global symmetries, we need building blocks for the Lagrangian (such as covariant derivatives) that seem similar to gauge theory ...
- 213
1
vote
1
answer
199
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Momentum maps and supersymmetry
While reading a paper by Gaiotto et al., I stumbled upon the concept of momentum maps where they are used in section 2.1 to characterise the vaccum structure of some theory.
I tried reading the ...
- 4,088
2
votes
1
answer
123
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Spontaneous Symmetry Breaking and gauge symmetry
As mention in David Tong's Lecture note:
Gauge symmetry is, in many ways, an odd foundation on which to build our best theories of physics. It is not a property of Nature, but rather a property of ...
- 171
2
votes
0
answers
79
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$U(1)_A$ axial anomaly for $SU(N)$ gauge theory in 1+1 dimensions
In massless Abelian gauge theory in 1+1 dimensions, the divergence of axial current is given by
\begin{align*}
\partial_\mu j_A^\mu=\frac{e}{2\pi}\epsilon^{\mu\nu}F_{\mu\nu}=\frac{e}{\pi}F_{01}.
\end{...
- 165
3
votes
1
answer
254
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Structure Group vs Gauge Group in Gauge Spontaneous Symmetry Breaking
Recently I’ve been learning about spontaneous symmetry breaking (SSB) for gauge theories. I’ve stumbled across some really helpful resources, such as Hamilton’s Mathematical Gauge Theory – With ...
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