All Questions
Tagged with quantum-field-theory gauge-theory
725
questions
5
votes
1
answer
268
views
Why is there only one coupling constant in Yang-Mills theory? Why are gluon self-coupling and gluon-matter coupling constants the same?
Is it non-trivial that the coupling constant $g$ in gluon self-interaction terms is the same as the coupling constant $g$ in gluon-fermion interaction term in Yang-Mills theory?
Pure Yang-Mills theory ...
- 192
3
votes
1
answer
89
views
Thirring Model effective potential
I have the lagrangian for the Thirring model coupled with vector interaction $V^\mu$ in the large-$N$ approximation:
\begin{equation}
\mathscr{L}=\bar{\psi}\left(i \gamma^\mu\partial_\mu-m - \gamma_\...
2
votes
1
answer
219
views
Cosmic Strings as Topological Defects (heuristics)
I have a lot of troubles to understand heuristically the principle behind Kibble's model for genesis of cosmic strings via Kibble mechanism. More precisely I not understand how to interpret following ...
- 1,395
1
vote
1
answer
80
views
Charged excitations and Vortices in abstract Abelian Lattice Gauge theory
I have a question about heuristical interpretation of certain used terminology in the setting of abstract Abelian gauge theories as used in this paper by Chenjie Wang, Michael Levin.
On page 4, Part A ...
- 1,395
1
vote
1
answer
191
views
Getting rid of the theta term in the standard electroweak theory
This has already been asked here more than once, but the existing answers do not tackle my misunderstanding.
A topological $\theta$-term is understood to be physical, in the usual particle model ...
- 1,742
1
vote
1
answer
55
views
Relation between Mass of Gauge Bosons and Range of Force in Terms of Asymptotic Calculus
Assume we have an Lagrangian $\mathcal{L}$ of matter field $\psi$ including interactive part mediated by gauge bosons $A_\mu$, eg structured "similary" to usual QED Lagrangian like
$$ D_\mu \...
- 1,395
-1
votes
1
answer
135
views
Hey there I'm a beginner in particle physics trying to "selfstudy" from online resources. I want to ask how much of what I learned is correct? [closed]
The information I have gained thus far regarding the standard model is;
fermions and how their intrinsic nature.
they have half spin, non zero mass, a charge, a weak hypercharge (for leptons), a ...
10
votes
3
answers
449
views
Is a QFT always an EFT coming from something deeper?
(I have already read this post but my question is different)
Reading Ch. 12 of Weinberg's Quantum Field Theory Vol. 1, he states that all realistic (interacting) QFTs are now believed to be EFT of ...
- 1,611
10
votes
4
answers
1k
views
How inaccurate is the following mental picture of particle interaction in QFT?
Context: I ask this as a school teacher reaching past the boundaries of my expertise. A colleague was talking about the standard model with an advanced student, explaining how particles interact by ...
- 2,452
3
votes
1
answer
237
views
Temporal Gauge with periodic boundary conditions
In Yang-Mills theory with periodic boundary conditions in time, is the temporale gauge, i.e. $A_0 = 0$, well defined?
Periodic boundary conditions would be
$$A_\mu(T_2,x) = A_\mu(T_1,x).$$
Naively I ...
- 2,263
2
votes
0
answers
83
views
Gauge invariance and Ward Identity?
I have to work on vacuum polarization and gauge contributions for a given problem.
I have to compute and show that their sum is gauge invariant, which according to the exercise, is equivalent to ...
- 310
1
vote
1
answer
159
views
Calculating a Gaussian-like path integrals with Grassmann variables and real variables
I want to compute the following path integral
$$Z[w] = \frac{1}{(2\pi)^{n/2}}\int d^n x \: \prod_{i=1}^{n}d\overline{\theta}_id\theta \: \exp{\left(-\overline{\theta}_i \partial_j w_i(x)\theta_j -\...
- 298
2
votes
0
answers
80
views
Peskin and Schroeder perturbative calculation of anomaly
On page 661 Peskin and Schroeder calculates the ABJ anomaly pertubatively. The book gives the ABJ anomly as
$$\tag{19.45}\partial_\mu j^{\mu 5}=-\frac{e^2}{16\pi^2}\epsilon^{\alpha\beta\mu\nu}F_{\...
- 789
1
vote
0
answers
165
views
Gauge boson self-interaction diagrams
On page 522 of Peskin and Schroeder, we try to calculate the self-energy of gauge boson. Figure 16.7 gives the following diagrams:
However, Peskin and Schroeder says there are three additional ...
- 789
0
votes
0
answers
75
views
How can we talk about the mass of $W^\pm$ bosons when they don't diagonalise the mass matrix?
In the electroweak lagrangian, after symmetry breaking we get $W^1_\mu,W^2\mu,W^3\mu$ and $B_\mu$ bosons. These fields don't however diagonalise the mass matrix $\frac{\partial^2V}{\partial\phi_i\...
- 248