All Questions
45
questions
6
votes
2
answers
358
views
Introduce Ghost Field to eliminate unphysical degrees of freedom in case of Photon Field
In wikipedia's article about ghost fields is stated the following which requires a bit more clarification:
An example of the need of ghost fields is the photon, which is usually described by a four ...
- 1,395
2
votes
1
answer
248
views
Difference between Gauge invariance and BRST invariance
Which is the difference between gauge invariance and BRST invariance? Is it the same symmetry? Is the BRST the extention of the gauge symmetry even on the ghost fields?
- 159
0
votes
0
answers
46
views
Non-linear symmetry and symmetry at quantum level
Can anyone explain me what does the statement mean:
"the BRST symmetry is a non-linear symmetry, so the BRST is also a symmetry at the quantum level"?
What does "at the quantum level&...
- 159
2
votes
1
answer
90
views
Peskin and Schroeder's discussion of the BRST operator
On page 519 of Peskin and Schroeder, the authors have the following discussion on the nilpotent BRST operator $Q$ that commutes with the Hamiltonian $H$.
Many eigenstates of $H$ must be annihilated ...
- 789
2
votes
1
answer
331
views
Nilpotency of the BRST operator
I'm styding chapter 16 of Peskin and Schroeder, in section 16.4 on the BRST symmetry, Peskin and Schroeder first checks (on page 518) that if $Q$ is the BRST symmetry operator, then $$Q^2\phi=0\tag{16....
- 789
3
votes
2
answers
556
views
BRST Symmetry and Single Particle States
I am studying about BRST symmetry from the book of P&S (Peskin's and Schroeder's "An Introduction to QFT", Chapter 16.4). The authors construct a nilpotent charge operator and then they ...
- 3,992
2
votes
1
answer
126
views
Antifields in BV formalism - do they also have gauge transformation laws?
I am studying Weinberg Vol 2 and the BV formalism of the gauge theory.
There, the antifields are introduced somewhat out of thin air. I am a little bit confused about their properties.
For example, ...
- 1,669
2
votes
1
answer
175
views
Vanishing of path integral over internal d.o.f. of test particle in $SU(N)$ gauge theory
In Ch-2 (Yang-Mills theory) of David Tong’s notes on gauge theory. Tong writes an action $$S_w=\int d\tau \hspace{2pt}i w^{\dagger} \frac{dw}{d\tau}+\lambda(w^{\dagger}w-k)+w^{\dagger}A(x^{\mu})w\tag{...
- 3,043
3
votes
1
answer
504
views
How does the BRST transformation act on ghost fields?
I understand the general idea behind constructing the BRST symmetry: take a generic gauge transformation
$$\begin{equation}
e^\omega,
\end{equation}\tag{1}$$
where $\omega$ is Lie-algebra valued, and ...
- 71
4
votes
1
answer
365
views
Intuition for Hilbert space of a quantized gauge theory
In the standard explanation, the physical Hilbert space of a quantized gauge theory (such as QCD) is given by the cohomology of the BRST charge acting on some larger, unphysical Hilbert space.
More ...
- 1,455
2
votes
0
answers
75
views
Current state of the Gribov-Zwanziger formalism and the softly broken BRST symmetry
I hope to get a little bit more clarification about the topics. My confusion arises from the fact that some authors (Lavrov et al) state that a gauge theory with softly broken BRST symmetry is ...
- 352
1
vote
0
answers
94
views
Faddeev-Popov for discrete gauge symmetry?
This excellent question here does not seem to have an acceptable answer. I have had precisely the same question recently.
Namely, the way BRST quantization is usually presented relies on some kind of ...
- 867
5
votes
0
answers
259
views
Resources on BRST and BV quantisation for local quantum field theories
This is a reference request, to ideally a textbook, monograph, set of lecture notes or lecture videos, on the topics of BRST quantisation and the Lagrangian BV formalism. My constraints are as follows:...
2
votes
1
answer
500
views
Batalin-Vilkovisky quantization
Batalin-Vilkovisky (BV) quantization is way of quantizing a theory, which is apparently more powerful than BRST quantization. It has been used, for example, for string field theory, in the closed ...
- 195
5
votes
4
answers
504
views
Gauge ghosts & unphysical states in gauge theory
I have a general question about a statement from Wikipedia about ghost states as occuring in gauge theory:
"In the terminology of quantum field theory, a ghost, ghost field, or gauge ghost is an ...
- 1,395