All Questions
Tagged with symmetry-breaking field-theory
61
questions
1
vote
1
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140
views
What is a symmetry defect?
I found that it is a normal concept appearing in condensed matter physics and especially topological order field. I have been aware of the topological defect. But what is a symmetry defect? Could ...
- 81
0
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0
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99
views
What is the topology of sine-Gordon equation?
In one pdf on solitons, I am finding the following written
For the sine-Gordon theory, it is much better to think of $\phi$ as a field modulo $2\pi$, i.e. as a function $\phi: R \rightarrow S_{1}$. ...
2
votes
1
answer
102
views
In QFT, are there any restrictions on spontaneous breaking $G\to H$, due to "spontaneity"?
For simplicity, let us restrict to the spontaneous breaking of global symmetries. Given any pair of groups $G\supset H$, is it always possible to find a $G$-invariant Lagrangian that gives a QFT such ...
- 213
2
votes
1
answer
60
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Which order multiplet of a given $SU(N)$ is real or complex?
I am studying the $SU(2)$ symmetric Lagrangian in particle physics.
$${\mathcal{L}} = (\partial_\mu \Phi)^\dagger (\partial^\mu \Phi) - (\mu^2 \Phi^ \dagger \Phi + \lambda (\Phi^ \dagger \Phi)^2).$$
...
- 399
1
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0
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72
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Quantization of spontaneously broken theory, which is not in the true vacuum
I wonder whether the source $J$ in QFT can make one to quantize the field when the system is in the excursion to the minimum. Precisely, I want to know that following process makes sence.
Suppose, I ...
- 13
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1
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246
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What's the difference between the global transformations of $SU(2)$ and $U(1)$?
I am studying the spontaneously broken global non-Abelian symmetry. Suppose we have an $SU(2)$ doublet of bosons $\Phi = (\phi^+, \phi^0)^T$, with Lagrangian density
$$
\mathcal L = (\partial_\mu\Phi^\...
- 1,783
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0
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169
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Taylor expansion of some Lagrangian (Understanding the Blundell's Quantum field theory, Example 26.5)
I am reading the Lancaster, Blundell's Quantum field theory for the Gifted Amateur, p.243, Example 26.5 and I can't understand some sentences and I don't know how to expand some Lagrangian.
I am a ...
- 327
4
votes
2
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873
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Local $SU(2)$ symmetry breaking and unitary gauge
In a $SU(2)$ gauge field theory with scalar field $\phi$ in the fundamental representation of the $SU(2)$ group with lagrangian $$\mathcal{L} = -\frac{1}{2}TrF_{\mu\nu}F^{\mu\nu} + (D_{\mu}\phi)^\...
- 43
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votes
0
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65
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Can Chiral symmetry violating term in lagrangian violate charge conversation?
The regular Lagrangian is
$\mathcal{L}=\bar{\psi}(i\gamma^\mu\partial_\mu-m)\psi$
If we add a chiral violating term
$\mathcal{L}=\bar{\psi}(i\gamma^\mu\partial_\mu-me^{i\theta\gamma^5})\psi$
For the ...
- 925
4
votes
0
answers
106
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Why are non-perturbative solutions important and how to take them into account?
I am guilty of studying physics with an almost complete focus on the mathematical constructions (together with the motivating physical premisses) and ignoring the semantic physical intuition, which I'...
- 1,742
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71
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Am I correctly interpreting Eq. (4.1) from Erick Weinberg's book, "Classical Solutions in Quantum Field Theory"?
I have been studying Erick Weinberg's book, "Classical Solutions in Quantum Field Theory", and I am confused about Eq. (4.1) from p. 58. I believe my issue of confusion is notational, and I ...
3
votes
1
answer
140
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Local order parameter for confinement in gauge theories
I would like some help clarifying what Zinn Justin is saying in his book "Quantum Field Theory and Critical Phenomena" p.805 on detecting confinement of gauge theories.
In particular, I ...
- 872
2
votes
1
answer
280
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Residual symmetry group of a scalar field theory
Given a Lagrangian
$$\frac{1}{2} (\partial_\mu \phi)^2 - \frac{\lambda}{4!}(\phi^2 - v^2)^2$$
for a real scalar field theory with $\vec{\phi} = (\phi_1,\phi_2,...,\phi_n)^T$ and $O(n)$ symmetry. Why ...
- 373
4
votes
3
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1k
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Why is the translational symmetry broken?
In the book Condensed Matter Field Theory by Altland, on page 5, it is given that
$$H[\pi, \phi]=\int d x\left(\frac{\pi^{2}}{2 m}+\frac{k_{\mathrm{s}} a^{2}}{2}\left(\partial_{x} \phi\right)^{2}\...
- 2,283
2
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1
answer
441
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Spontaneous symmetry breaking, massless bosons and the equations of motion
I am currently studying spontaneous symmetry breaking, and I don't entirely understand the implications of what we are doing at certain places. Consider the standard complex scalar field with the $\...
- 107