The anomaly tag has no wiki summary.
6
votes
1answer
80 views
Critical dimension in quantization of p-branes
So I have what might be a fairly basic question, but my understanding that in the quantization of the the string, or the 1-brane, there are conditions on the number of spacetime dimensions to ensure ...
5
votes
1answer
208 views
Path integral with zero energy modes
Consider the field integral for the partition function of a free non-relativistic electron in a condensed matter setting, i.e.
$$ Z = ∫D\bar\psi D\psi \exp\left(-\sum_{k,ω} \bar\psi_{k,ω} (-iω + ...
13
votes
3answers
340 views
Homotopy $\pi_4(SU(2))=\mathbb{Z}_2$
Recently I read a paper using $$\pi_4(SU(2))=\mathbb{Z}_2.$$ Do you have any visualization or explanation of this result?
More generally, how do physicists understand or calculate high dimension ...
8
votes
1answer
157 views
why are two higgs doublets required in SUSY?
I can't really understand why two higgs doublets are required in SUSY.
From the literature, I have found opaque explanations that say something along the lines of: the superpotential W must be a ...
6
votes
1answer
165 views
Chiral anomaly in odd spacetime dimensions
In odd number of space-time dimensions, the Fermions are not reducible (i.e. do not have left-chiral and right-chiral counterparts).
Does this mean that there is no such thing as 'chiral' anomalies ...
1
vote
0answers
104 views
Why does renormalization need an unbroken symmetry?
Common wisdom is that for a QFT to be renormalizable it must be invariant under a symmetry transformation. Why does renormalization need an unbroken symmetry? Which is the first publication that ...
5
votes
1answer
249 views
simple explanation of chiral anomaly?
Can somebody provide a fairly brief explanation of what the chiral anomaly is? I have been unable to find a concise reference for this. I know QFT at the P&S level so don't be afraid to use math.
5
votes
2answers
319 views
If gauge symmetries are fake, then why do we care if they are anomalous?
My understanding is that gauge symmetries are fake in that they are only redundancies of our description of the system that we put in (either knowingly or unknowingly) see Gauge symmetry is not a ...
5
votes
1answer
259 views
what is the relationship between these two sorts of anomalies?
Recently there has been a few questions about anomalies in QFTs:
Why do some anomalies (only) lead to inconsistent quantum field theories
Classical and quantum anomalies
In these, people have been ...
6
votes
2answers
403 views
Why do some anomalies (only) lead to inconsistent quantum field theories
In connection with Classical and quantum anomalies, I'd like to ask for a simple explanation why some anomalies lead to valid quantum field theories while some others (happily absent in the standard ...
13
votes
1answer
600 views
Classical and quantum anomalies
I have read about anomalies in different contexts and ways. I would like to read an explanation that unified all these statements or point-views:
Anomalies are due to the fact that quantum field ...
4
votes
0answers
110 views
Relation among anomaly, unitarity bound and renormalizability
There is something I'm not sure about that has come up in a comment to other question:
Why do we not have spin greater than 2?
It's a good question--- the violation of renormalizability is linked
...
3
votes
2answers
598 views
Why does string theory require 9 dimensions of space and one dimension of time?
String theorists say that there are many more dimensions out there, but they are too small to be detected.
However, I do not understand why there are ten dimensions and not just any other number?
...
2
votes
1answer
298 views
Chiral anomalies à la Fujikawa: Why don't we just take another measure?
When deriving the chiral anomaly in the non perturbative approach for a theory of massless Dirac fermions, you start by showing that the path-integral measure is not invariant unter the chiral ...
9
votes
1answer
218 views
Instantons, anomalies, and 1-loop effects
A symmetry is anomalous when the path-integral measure does not respect it. One way this manifests itself is in the inability to regularize certain diagrams containing fermion loops in a way ...
2
votes
1answer
443 views
Chiral anomaly and decay of the pion
I am told that if all classical symmetries were reflected as quantum symmetries, the decay of the neutral pion $$\pi^0 ~\longrightarrow~ \gamma\gamma$$ would not happen. Why would the conservation of ...
