All Questions
32
questions
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
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
2
votes
1
answer
294
views
Why standard model uses Lie groups like $SU(2)$ and not $SL(2,\mathbb{C})$?
First of all, the question is written in section $2)$. Also, I known that the $SU(2)$ group do not appears "alone" in standard model, rather, inside the Glashow-Salam-Weinberg model.
1) ...
- 3,085
0
votes
1
answer
224
views
What is the Mathematical description of Weak Interaction at low energies?
Introduction
When I started to study gauge theory the mathematical road map seemed to be quite "simple". After all the concepts and notions about principal the differential geometry of fibre ...
- 3,085
0
votes
0
answers
63
views
Gauge Groups in Nature [duplicate]
It is well known that the relevant gauge groups appearing in particle physics are $U(1)$, $SU(2)$, and $SU(3)$. In many respects these are among the simplest Lie groups, such as in the dimension of ...
2
votes
2
answers
256
views
Why do we demand $SU(2)$ and $SU(3)$ gauge invariance when we construct the standard model?
If one tries to verify the construction of the standard model, one has to find a Lagrangian that is invariant under $U(1)\times SU(2) \times SU(3)$. While it seems kind of logic that the Lagrangian ...
- 437
1
vote
2
answers
175
views
Can the weak interaction be studied without bothering the electromagnetic one?
It is well known that the electroweak interaction can be studied as a $SU(2)_L \otimes U(1)_Y$ gauge theory. It is also known that the electromagnetic interaction is a $U(1)$ gauge theory, and it ...
- 5,931
0
votes
0
answers
131
views
$U(1)^{3} $ anomaly, trace of a hypercharge?
I have recently found the definition of the $U(1)^{3}$ anomaly as:
$$\mathcal{A} = Tr[Y^{3}]_{L} -Tr[Y^{3}]_{R} $$
Where $Y$ is the hypercharge of the left, $L$ or right, $R$ components. What I don't ...
1
vote
2
answers
373
views
Why $W^+$ and $W^-$ bosons counted as two types of particles? but not $e^+$ and $e^-$?
The $W^+$ and $W^-$ bosons have either a positive or negative electric charge of 1 elementary charge and are each other's antiparticles.
In this sense, if we know the properties of $W^+$, we should ...
- 4,336
2
votes
2
answers
850
views
What precisely and mathematically does it mean to say gauge bosons as elementary particles?
In standard particle physics textbook, we say that photons, gluons and $W$ and $Z$ bosons are gauge bosons as elementary particles.
However the gauge bosons are vector bosons and they carry the form ...
- 4,336
0
votes
0
answers
79
views
What precisely and mathematically does it mean to have $W$ bosons carry electric charges?
What precisely and mathematically does it mean to have $W$ bosons carry electric charges?
We know from Wikipedia that experiments say that $W$ bosons carry electric charges:
$W^\pm$ carry $+$ and $-$ ...
- 4,336
14
votes
4
answers
2k
views
Haag's comment on the relation between fields and particles
I am very confused by the statement made in Haag's, Local Quantum Physics: Fields, Particles, Algebras (page 46):
... the idea that to each particle there is a corresponding field and to each field a ...
- 3,915
2
votes
0
answers
321
views
Anticommutator of gauge covariant derivatives
I must convert some dimension-6 operators I've obtained to the SILH base (ref: this, "Review of the SILH basis", CERN presentation by R. Contino).
In this conversion I've got operators such ...
- 127
1
vote
0
answers
42
views
Are there fermionic bound states that are gauge neutral to all gauge forces?
Puzzle: In our standard model particle physics, are there fermionic bound states that are gauge neutral to all gauge forces?
Here we concern strong SU(3) color, electromagnetic U(1) EM, hyper U(1), ...
- 4,336
8
votes
3
answers
478
views
Are neutrons gauge neutral to all gauge forces?
Are neutrons gauge neutral to all gauge interactions?
Neutron has mass, so it does couple to gravity.
However, if we focus on the strong, electromagnetic EM, and weak forces,
are there gauge ...
- 4,336