All Questions
Tagged with quantum-anomalies condensed-matter
17 questions
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Anomalies and SPT phases
There seems to be some connection between anomalies and Symmetry Protected Topological Orders, but I cannot find exact details of what the relation is. My impression is that group cohomology and ...
- 178
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0
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182
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How can i calculate the Berry Curvature for the Dirac points in Haldane graphene?
I want to calculate the berry curvature at the Dirac points in graphene with complex next nearest hopping (haldane model) in order to show that it is non-zero at the dirac points and use it to compute ...
- 213k
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300
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What intuition led to J. Wang and X.G. Wen's lattice formulation of the 3450 chiral gauge theory?
In the paper cited below, Juven Wang and Xiao-Gang Wen give an example of a lattice model that reduces to a chiral $U(1)$ gauge theory at low energy. The low energy theory is called the $3450$ model. ...
- 55k
7
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On-site symmetries can be gauged, but is a gaugeable symmetry necessarily on-site?
I've always liked lattice QFT because it's mathematically unambiguous and non-perturbative, but it does have two drawbacks: (1) the lattice is artificial, and (2) some features are messy. One of those ...
- 8,134
5
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Phenomenology application of quantum anomaly
Anomaly means that: the system has a symmetry at classical level (both discrete and continous), but when we quantize the theory, the system no longer holds the symmetry.
I'm wondering for every ...
- 932
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Chiral anomaly in Weyl semimental
In Weyl semimetal, there is an analog of ABJ anomaly, which is a $E \cdot B$ term. The ABJ anomaly can be viewed as winding number because of the homotopy group of sphere $\pi_3(S^3)= \mathbb{Z}$ for ...
- 213k
7
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2
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Anomaly inflow mechanism
I know very simple example of anomaly inflow. See section 4.4 in David Tong: Lectures on Gauge Theory. As I read, such mechanism have some applications in condensed matter and in quantum field theory, ...
- 4,893
3
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Anomalies on boundary and bulk physics
Few times I faced with such statements:
The gravitational anomaly of the 1+1d boundary system is known to be
proportional to the thermal Hall conductivity of the 2+1 dimensional
bulk
How ...
- 56.6k
3
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2
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291
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In what condensed matter systems (without chiral anomaly) do we need two $U(1)$ gauge fields?
In condensed matter systems, we use a $U(1)$ gauge field to describe the electric current by charge carriers. If there is a chiral anomaly, there will be a vector $U(1)$ and an axial $U(1)$. Suppose ...
- 4,833
2
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160
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"Mixed anomaly" in Weyl semimetal and its cancellation
The introduction to the problem
Suppose the Weyl semimetal (read please briefly the definition before reading the question). Because of the effective nature of the chirality the parameters $b_{0}, \...
- 213k
6
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What is the reason for chiral anomalies in condensed matter systems?
If you consider a massless relativistic fermion theory and you perform a chiral transformation, then you realize that while the classical action remains invariant under this transformation the ...
- 213k
6
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1
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Chiral anomaly in Weyl semimetal
In the presence of electromagnetic fields $E$ and $B$, four current is not conserved in a Weyl semimetal i.e. $\partial_{\mu} j^{\mu}\propto E\cdot B \neq 0$. There are some proofs in the literature ...
- 213k
0
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118
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A Universe with only a single fermion
Is a Universe with only a single fermion anomalous instead of free from anomalies?
(e.g. electron, defined through fermi statistics with exchange statistics with a gained $-1$ sign, or rotating 360 ...
CommunityBot
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The anomalous Hall effect in Weyl semimetals
Suppose the semimetal - the solid material, in which the conducting and valence zones are intersected at isolated points - the so-called Weyl nodes. Near this points, the Hamiltonian of electrons is ...
- 8,971
8
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Zumino's consistent and covariant anomalies - applied to quantum hall?
What is the `physical' meaning of consistent anomalies and covariant anomalies?
Perhaps a good Reference is:
Consistent and covariant anomalies in gauge and gravitational theories -
William A. ...
- 56.6k
4
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516
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Anomaly for Majorana fermion?
In 4-spacetime dimension, is there U(1) gauge field chiral anomaly associated with Majorana fermion (or I am not sure if it is equivalent, majorana representation)? Besides, I have read from several ...
- 531
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Descent equation and anomaly polynomial [closed]
I am just reading Ryu, Moore and Ludwig's paper on classifications of topological insulators and quantum anomaly. They are trying to relate the quantum anomaly as a signal of the presence of a ...
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