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Results tagged with quantum-field-theory
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user 1039
Quantum Field Theory (QFT) is the theoretical framework describing the quantisation of classical fields which allows a Lorentz-invariant formulation of quantum mechanics. QFT is used both in high energy physics as well as condensed matter physics and closely related to statistical field theory. Use this tag for many-body quantum-mechanical problems and the theory of particle physics. Don’t combine with the [quantum-mechanics] tag.
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Particle Lagrangians
As spin has no classical analog, you either need to start with a classical field theory, or a quantum wave function.
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Is quantum field theory defined by its lattice regularization?
Unless someone can show how to come up with chiral fermions and avoid the fermion doubling problem over a lattice, it's clear lattice regularizations can't cover everything. That person would have to …
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What would the electromagnetic field of a massless electron look like
With a massless charged fermion, the electromagnetic coupling strength will be totally screened, with $1/e^2$ increasing logarithmically with the scale $R$. The electric field will be Coulomb multipli …
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Superconformal theories
The functional space of all possible field configurations of a primary field is always a representation of the conformal group.
For most choices of tensors and conformal weights, this representation i …
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Can I couple a chiral fermion to electrodynamics?
Sure you can. However, it's not possible to only couple one charged chiral fermion. Gauge anomalies need to be cancelled for consistency. Summing up the cube of all the charges of left handed chiral f …
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why certain superpositions of quantum states are supressed?
The total electric flux at infinity will always decohere states with different charges exactly. This is the cause of the superselection rules.
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What is the difference between a complex scalar field and two real scalar fields?
They're identical. Typically, we use complex fields if we have a $U(1)$ symmetry, or some more complicated gauge group with complex representations.
Incidentally, the same comment applies to whether …
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What equation describes the wavefunction of a single photon?
According to Wigner's analysis, the single photon Hilbert space is spanned by a basis parameterized by energy-momenta on the forward light cone boundary, and a helicity of $\pm 1$.
However, a manife …
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Spinning Tachyons
If the polarizations of a tachyonic vector boson are Lorentz covariant, then its norm has to be indefinite, not positive definite, or positive semidefinite as in the case of massless vector bosons. Th …
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What is the density of virtual photons around a unit charge?
It's infinity. This is the soft photon problem, which requires infrared regularization.
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