Tagged Questions
Quantum Field Theory (QFT) is the theoretical framework describing the quantisation of classical fields which allows a Lorentz-invariant formulation of quantum mechanics. QFT is used both in high energy physics as well as condensed matter physics and closely related to statistical field theory. Use ...
2
votes
0answers
16 views
Is the second derivative of the effective potential always the mass square of the particle?
In quantum field theory, we can calculate the effective potential of a scalar field. My question is whether the second derivative of the effective potential always represents the mass square of the ...
8
votes
1answer
101 views
Conceptual difficulty in understanding Continuous Vector Space
I have an extremely ridiculous doubt that has been bothering me, since I started learning quantum mechanics.
If we consider the finite dimensional vector space for the spin$\frac{1}{2}$
particles, ...
3
votes
0answers
39 views
Some questions about the large-N Gross-Neveu-Yukawa model
Consider the following action with a fermionic field $\psi$ and a scalar field $\sigma$,
$S = \int d^dx \{ -\bar{\psi}(\gamma^\mu \partial_\mu +\sigma )\psi + \Lambda^{d-4}[ \frac{(\partial_\mu ...
4
votes
1answer
118 views
Green's function in path integral approach (QFT)
After having studied canonical quantization and feeling (relatively) comfortable with it, I have now been studying the path integral approach. But I don't feel entirely comfortable with.
I have the ...
3
votes
0answers
22 views
QCD string breaking and glueballs
When one tries to pull two quarks appart, a flux tube is created.
The tube eventually breaks, creating quark anti-quark pairs and eventually hadrons.
Can there also be creation of gluons to form ...
2
votes
0answers
26 views
A question about the constraints in BRST-Fock theories
In BRST Symmetry in the Classical and Quantum Theories of Gauge Systems, Henneaux says the Fock representation is not applicable to an odd number of constraints. Then he goes on to say that the ...
1
vote
0answers
53 views
Quantum Field Theory and Lie Theory [duplicate]
I am reading Vol.1 of "The Quantum Theory Of Fields" by S. Weinberg. However I have come to a halt when connected Lie groups were introduced. I have solid knowledge in elementary group theory and ...
8
votes
0answers
66 views
Mathematical motivation of OPE?
In Peskin & Schroeder (and also Cheng which I have skimmed through) they motivate the Operator Product Expansion with a lot of words.
Is there any way to motivate it mathematically, e.g. Taylor ...
2
votes
1answer
46 views
Same U(1) charge for the SU(2) doublet
Consider the symmetry $SU_L(2)\otimes U_Y(1)$. The entries of $SU_L(2)$ doublet will have same U(1)-charge. How can this be shown mathematically?
2
votes
1answer
50 views
Adjoint of Gamma Matrices - Dirac
I just started to learn how to quantise Dirac field. Meanwhile, as we can write the Dirac equation in terms of gamma matrices :
$$ (i\hbar\gamma^\mu\partial_\mu - m)\psi = 0 $$
where $\gamma_\mu$ ...
1
vote
1answer
65 views
Massless neutrinos and Chirality
The massless neutrinos can be represented by two component Weyl spinors. Then how does one say that it is an eigenstate of the chirality operator $\gamma^5$, which is a $4\times 4$ matrix and can act ...
4
votes
0answers
43 views
(Euclideanized) QFT on $S^d$ vs $S^{d-1}\times S^1$
Broadly I would like to understand what is the difference in the physical interpretation of a (Euclideanized) QFT which is on space-time $S^d$ and which is on a space-time $S^{d-1}\times S^1$.
In ...
3
votes
0answers
34 views
Finding the ground state of the toric code Hamiltonian
How do I write by proof, the ground state of the toric code (by Kitaev) Hamiltonian $ H=-\sum_{v}A(v)-\sum_{p}B(p) $ where $A(v)=\sigma_{v,1}^{x}\sigma_{v,2}^{x}\sigma_{v,3}^{x}\sigma_{v,4}^{x}$
and ...
7
votes
0answers
87 views
+50
Different classes of non-abelian anyons
Say we have different types of non-abelian anyons described by $SU(2)$-Chern-Simons theory, so the anyon charges are irreducible representations of the corresponding Lie algebra. In the algebraic ...
0
votes
0answers
25 views
Defining Euclidean conjugate?
We saw Hermitian conjugate in quantum mechanics frequently but I want to know defining of Euclidean conjugate. I encountered it in $SU(2)$ spinors.
