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Aug
16
revised Why do some anomalies (only) lead to inconsistent quantum field theories
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Aug
13
comment First class and second class constraints
When all the 5 constraints are first class, then one has to choose 5 functions on the phase space (gauge fixing conditions)$\chi_{\alpha}$, such that the matrix $M_{\alpha\beta} = \{\chi_{\alpha}, \phi_{\beta}\}|_{\Sigma^{\prime}}$ is every where nonsingular on the constraint plus gauge fixing surface $\Sigma^{\prime}$
Aug
13
revised First class and second class constraints
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Aug
13
answered First class and second class constraints
Aug
12
answered Why do some anomalies (only) lead to inconsistent quantum field theories
Aug
2
comment Classical and quantum anomalies
Actually, I have a little more information on this subject. I'll try to add an update when I can
Aug
2
comment Classical and quantum anomalies
(cont.) webcache.googleusercontent.com/…
Aug
2
comment Classical and quantum anomalies
(cont.) But, if one uses the Sugawara construction for the Virasoro generators from the current generators, the Virasoro central charge (in the Poisson brackets) will be zero. However, in the Liouville theory one already obtains a nonvanishing Virasoro central charge in the Poisson brackets, please see the following article by Toppan:
Aug
2
comment Classical and quantum anomalies
Here are some examples referring to both your questions. In the WZNW model in two dimensions, one gets the Kac-Moody algebra at the classical level (Poisson brackets) with the correct central charge. In fact this computation was performed by Witten in his original article: projecteuclid.org/…. For a more clear derivation please see: citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.148.8249
Aug
1
revised Bohr model with all Quantum numbers for hydrogen atom
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Aug
1
revised Bohr model with all Quantum numbers for hydrogen atom
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Aug
1
comment Classical and quantum anomalies
I have added an update with the elaboration of the spin case
Aug
1
revised Classical and quantum anomalies
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Aug
1
answered Bohr model with all Quantum numbers for hydrogen atom
Jul
31
comment Classical and quantum anomalies
When the representation on the wave functions is a ray representation,it is an indication of an anomaly, because the symmetry group is not represented faithfully. Of course group extensions can be studied in general separately from quantum mechanics. I'll update my answer tomorrow and add a few more references.
Jul
31
answered Classical and quantum anomalies
Jul
31
comment Gauge fixing choice for the gauge field $A_0$
(cont.), please see the following review by: ANTTI SALMELA ethesis.helsinki.fi/julkaisut/mat/fysik/vk/salmela/gausssla.pdf
Jul
31
comment Gauge fixing choice for the gauge field $A_0$
But if one subtitutes $A_0 = 0$ in the Lagrangian before the computation of the equations of motion, then equation of motion of $A_0$, namely, the Gauss law will be lost, because one will not have an $A_0$ in the Lagrangian to take a variation with respect to it. In this case one has to impose the Gauss law "by hand".
Jul
31
awarded  quantum-mechanics
Jul
30
answered Gauge fixing choice for the gauge field $A_0$