All Questions
18
questions
3
votes
0
answers
44
views
Multiple excitations of composite bosons?
Fundamental bosons, which are the mediators of the Standard Model interactions, are permitted to have multiple excitations with the same quantum number. Fermions, on the other hand, obey the Pauli ...
- 2,921
1
vote
0
answers
44
views
Can the Keldysh occupation function have a zero for bosons or a pole for fermions?
In the Keldysh framework for nonequilibrium dynamics of quantum systems we learn that there are essentially two Green's functions that characterize a system: the retarded Green's function $G^R(\omega)$...
- 164
3
votes
0
answers
358
views
Can one combine Jordan-Wigner Transformation and Schwinger-Boson Representation?
Is it technically possible to map a fermionic problem with $M$ Orbitals to a bosonic problem with $2M$ orbitals by combining the Jordan-Wigner transformation with the Schwinger-Boson representation? ...
- 184
1
vote
0
answers
104
views
Swap fermion with boson?
I wonder what actions/factors/terms show up when you swap a fermion and boson that are tensored together in second quantisation. It would suffice for me if someone could give me the name of such an ...
- 693
1
vote
0
answers
426
views
A proof that Heisenberg's and Euler Lagrange's equations are equivalent in QFT [closed]
I asked this before (link, link) but I think people didn't understand what I was asking, so I am going to try again . Thanks for everyone that helped so far.
In QFT, Heisenberg's equation is ...
- 267
8
votes
6
answers
1k
views
Can we ever "measure" a quantum field at a given point?
In quantum field theory, all particles are "excitations" of their corresponding fields. Is it possible to somehow "measure" the "value" of such quantum fields at any point in the space (like what is ...
- 1,145
3
votes
1
answer
785
views
Quantum statistics from the (anti)commutation relations of the operators?
From a QFT point of view, the difference between bosons and fermions is that their creation/annihilation operators ($a^{\dagger}$, $a$ and $c^{\dagger}$, $c^{\dagger}$ respectively) obey the following ...
- 24.9k
1
vote
2
answers
419
views
How do I know that gauge fields are bosons?
QED and the Dirac equation have field operators $\psi$ interact with a gauge field $A^{\mu}$.
We identify $\psi$ as a fermionic field and $A^{\mu}$ as a gauge boson - the photon.
Do we or can we ...
- 24.9k
7
votes
1
answer
695
views
Fock space with mixed anti-commutation/commutation relations?
Let's say we have two modes, with the following labeling of occupation number states:
$ \lvert \Psi \rangle = \begin{pmatrix} 0,0 \\ 0,1 \\ 1,0 \\ 1,1 \end{pmatrix} $
An example of (what I assume to ...
- 395
11
votes
1
answer
2k
views
Chemical potential in quantum field theories
The chemical potential enters the grand canonical ensemble, in statistical physics, as the Lagrange multiplier ensuring the conservation of particle number.
In QFT and relativistic theories in ...
- 24.9k
6
votes
1
answer
471
views
Bosonization and Commutation Relation
I'm playing a bit with bosonization $ψ→:e^{-φ}:$ and $ψ^*→:e^{φ}:$ in the sense that
$$
\Bigg\langle 0_\mathrm{F} \Bigg|∏_{i=1}^nψ(z_i)ψ^*(w_i)\Bigg|0_\mathrm{F}\Bigg\rangle = \Bigg\langle 0_\mathrm{...
- 1,536
4
votes
1
answer
790
views
Fields: Bosons vs Fermions
Reading Student Friendly Quantum Field Theory by Robert Klauber and he made me realize I've taken as fact for some time that bosons are the "force carriers" in QFT, without really understanding fully ...
- 517
1
vote
1
answer
3k
views
Integral spin and half integral spin
I am reading a book (Laudau and Lifshitz, Vol. 4, page 94) and it derived why spin-0 should obey Bose quantization and spin-1/2 should obey Fermi Quantization.
Then it says, all integral spin ...
- 890
7
votes
2
answers
5k
views
What is meant by fermionic and bosonic "modes"?
The paper The Dirac quantum automaton: a short review (pdf) starts off by stating:
The starting point for the construction of space–time and the physical laws therein is an unstructured, countably ...
- 2,200
1
vote
0
answers
449
views
Path integral for boson vs fermion (soft derivation + use )
I have been looking around for a soft derivation with a bit of detail for boson and fermion path integrals that I could understand. I have a passing knowledge generally of what a path integral is in ...
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