All Questions
11
questions
1
vote
2
answers
108
views
Checks of anomaly cancellation
In a textbook I read that if $G$ is a global symmetry of the classical Lagrangian, then one has to check $G\times H^2$ anomalies, where $H$ is one of the SM gauge groups.
For example, when $G$ refers ...
- 51
1
vote
0
answers
61
views
Form of SM hypercharge current and anomalies
I have a doubt regarding the SM hypercharge current associated with the $U(1)_Y$ global symmetry (note: I want to work in the unbroken phase, we have the doublet H and the Yukawas)
$\psi \to e^{i\...
- 130
0
votes
1
answer
165
views
What is the connection between the electroweak energy scale and the vacuum expectation value?
I am quite confused about energy scale and vacuum expectation value (VEV). For example, this wiki page says 246Gev is VEV of Higgs field. Does it mean if we go to a higher energy scale (like 24600Gev)...
- 995
-1
votes
1
answer
161
views
Is the Standard Model, in some sense, special relativity plus everything possible?
I found this intro to QFT on YouTube really helpful (and apparently I'm not the only one). Let my try to summarize it:
We start with Minkowski space. We want to add a field to it, but there are only ...
- 2,475
1
vote
0
answers
47
views
Why is there no $H_1H_1\bar{e}^c$ term in the most general renormalisable superpotential?
I am these notes by Jeff Asaf Dror on Supersymmetry. In the section on the MSSM, it is stated that the most general renormalisable superpotential is given by
$$W=y_1QH_2\bar{u}^c+y_2QH_1\bar{d}^c+...
- 857
0
votes
2
answers
97
views
Is it possible to falsify the $SU(2)_{lepton, left}*SU(2)_{quark, left}*U(1)$ symmetry group as an alternative candidate for GSW Model?
We know that the current symmetry of GSW is $SU(2)_{fermions, left}*U(1)$, and the correct representation of the $SU(2)_{fermions, left}$ is the $2+2$ representation.
I want to know what is the reason ...
- 1,268
7
votes
1
answer
248
views
Standard model: Why linear representation?
I'm trying to understand better the idea of the standard model, where particle states are described within vector spaces corresponding to irreducible representations of the group of symmetry of ...
- 206
1
vote
1
answer
152
views
What is the connection between Lagrangian symmetry and particle multiplets?
I am struggling to see the connection between the symmetries of Lagrangians and particle multiplets. If I had three quark fields arranged in a vector $\Psi(x) = (u(x),d(x),s(x))$, these three fields ...
- 3,986
6
votes
2
answers
1k
views
What forbids off-diagonal elements in the kinetic terms of the Standard Model?
In the Standard Model, the gauge covariant kinetic term for the left-handed lepton doublets $\psi_{iL}=(\nu_{iL},e_{iL})^T$, for example, is given by $$i\overline{\psi_{iL}}\gamma^\mu D_\mu\psi_{iL}.$$...
- 26.8k
3
votes
2
answers
349
views
Global symmetry and particle multiplets
In chapter 20, of Peskin and Schroeder's quantum field theory book, they start with a comment that a global symmetry that is manifest lead to particle multiplets with restricted interactions. Can ...
- 26.8k
54
votes
2
answers
2k
views
Symmetries of the Standard Model: exact, anomalous, spontaneously broken
There are a number of possible symmetries in fundamental physics, such as:
Lorentz invariance (or actually, Poincaré invariance, which can itself be broken down into translation invariance and ...
- 810