All Questions
Tagged with higgs gauge-invariance
28
questions
2
votes
0
answers
64
views
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
2
votes
0
answers
62
views
Predicting a nonzero mass for the photon
This is a concern I had after I had read the reply for a previous question I had: On the masslessness of the photon
So, I have been told that there are cases in which the gauge symmetry that preserves ...
- 3,982
2
votes
0
answers
128
views
What is the current theoretical and experimental understanding of the mass of the photon? [duplicate]
To what extend are we allowed to claim that the photon has some sort of mass, below some threshold. We certainly have no experimental evidence that the photon is completely massless, but, due to the ...
- 3,982
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
0
votes
1
answer
236
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Unitarity gauge in Higgs mechanism in P&S's QFT
To my understanding, after spontaneous symmetry breaking, if we parametrized Higgs field:
$$\\ \phi(x)= \frac{1}{\sqrt{2}} \left(\begin{array}{c} 0 \\ v+h(x) \end{array}\right)e^{i\pi(x)/v}, $$
we ...
- 1,421
4
votes
2
answers
873
views
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
5
votes
0
answers
164
views
Intuition/Motivation behind necessity of Spontaneous Symmetry Breaking to generate massive gauge bosons
In field theory textbooks, it is shown that while any gauge invariant Lagrangian must involve massless gauge fields, to obtain massive gauge bosons, we must postulate the existence of a Higgs scalar ...
- 1,588
1
vote
1
answer
139
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A question about charge in the gauge covariant derivatives of the $U(1)$ Higgs model
I'm studying the $U(1)$ Higgs model, with the lagrangian:
\begin{gather}
\mathcal{L}=-\frac{1}{4}F^{\mu\nu}F_{\mu\nu}+\left(D_\mu\phi\right)\left(D^\mu\phi\right)^\dagger-\mu^2\left(\phi\phi^\dagger\...
6
votes
3
answers
807
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Review: If true, what makes the vacuum of a local ${\rm U(1)}$ gauge theory unique?
Long back, I posted a question with title Is the vacuum of a local ${\rm U(1)}$ gauge theory unique?, which, as the title suggests asked whether the vacuum of a "spontaneously broken" the ...
- 26.7k
7
votes
1
answer
827
views
Vacuum expectation value (VEV) of a Gauge theory - Spontaneous Symmetry Breaking (SSB) - Higgs Mechanism
I am dealing with a sort of scalar QED with a term of SSB
\begin{equation}
\mathcal{L}=\left|D_{\mu} \phi\right|^{2}-\frac{1}{4}\left(F_{\mu \nu}\right)^{2}-V\left(\phi^{*} \phi\right)
\end{equation}
...
- 900
1
vote
2
answers
830
views
Higgs mechanism and gauge symmetry
In the case of massive bosons of weak interaction we have Higgs mechanism to save the symmetry. I do not see how with Higgs the symmetry is preserved? Because the mass term is what gives us problems ...
- 1,803
2
votes
0
answers
165
views
Higgs amplitude mode vs. "spontaneous breaking" of local gauge symmetry
It seems that there are two definitions of the Higgs mode; one primarily used in particle theory, and one used in condensed matter. In the former, we can consider a simple Lagrangian of the form
$$
\...
- 2,665
2
votes
2
answers
1k
views
Misconceptions in spontaneous symmetry breaking
Spontaneous symmetry breaking occurs when we have a potential like a mexican hat as shown in figure (right) and is unbroken for the potential shape as shown in left figure. Under the Symmetry ...
- 468
7
votes
1
answer
659
views
Is the electroweak $SU(2)$ gauge symmetry an exact symmetry in Standard Model before spontaneous symmetry breaking?
In Standard model, components of a $SU(2)$ doublet (for example $u$ and $d$) have different masses. This means there is no $SU(2)$ symmetry, but I think it is okay because the $SU(2)$ symmetry is ...
- 165
8
votes
1
answer
533
views
Counting degrees of freedom in the Higgs mechanism for different gauges
I am wondering how to count the degrees of freedom (dof) for a massive gauge field in different gauges. I've been reading some other answers, but haven't found a solution yet.
I am looking at the ...
- 2,648