# All Questions

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### Conceptual questions on the path integral formulation of QFT

I'm currently trying to teach myself the path integral formulation of QFT (having studied the canonical approach previously), but I'm having some conceptual difficulties that I hope I can clear up ...
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### Quasi-fermi niveaus in a solar cell?

I was wondering, if my fermi niveau splits up due to n and p type doping into two fermi niveaus, one for the p type one for the n type, and now due to light radiation my fermi niveaus split up into 2 ...
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### Why exactly do sometimes universal covers, and sometimes central extensions feature in the application of a symmetry group to quantum physics?

There seem to be two different things one must consider when representing a symmetry group in quantum mechanics: The universal cover: For instance, when representing the rotation group ...
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### Can atoms exist [duplicate]

Can an atom be created from 2 top and one bottom quark together with a tau selectron? How would its properties differ from a hydrogen atom? What combinations of quarks and selectrons are possible to ...