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Results tagged with interactions
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Particle interactions are changes in the nature, number, or state of several particles, usually at a specific space-time point, underlying dynamics. They are represented by special "field interaction terms" in quantum field theory and normally entail interchanges of energy, momentum, and sundry quantum numbers. They include scattering, and particle creation and annihilation.
30
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Triviality of interacting QFT
In four dimensions the particles only intersect in isolated points -- not so much interactions therefore. … In more than four dimensions the trajectories of randomly walking particles typically do not self intersect, and so no matter how strong the interactions, nothing happens -- the theory is free. …
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5
votes
$\phi^4$-theory: interpreting the RG flow
The mass in the system is the inverse of the correlation length, which is infinite everywhere along the line labeled by F, as that is the line of critical points separating the broken symmetry phase …
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2
votes
Feynman rule for deriative interaction: an example
Usually such terms alter the Feynman rules in a subtle way through the measure in the functional integral. A non-linear sigma model in d=2 is a standard example. You have to add terms to the action c …
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2
votes
Accepted
Is $\phi^4$ theory an attractive or repulsive force?
If $\lambda>0$, the force is repulsive. If it $\lambda<0$, the force is attractive, but the system is unstable to vacuum decay.
To be more specific $\lambda \phi^4$ interaction is the relativistic ve …
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1
vote
Expectation values of interacting fields
The interpolating field couples to many states. This is summarized by the Lehaman-Kallen spectral representationfor the interacting propagator. Most field thoery books will have a discussion of this. …
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1
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Yukawa Couplings of Fermions to Higgs Field
There is a theory that links the Higgs to the top quark mass and suggests that the Higgs is a top quark condensate.
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1
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How to integrate out linear terms in Lagrangian?
There won't be any simple answer to this process. The resulting effective action will be minus the logarithm of the functional determinant of the Dirac operator that appears in the action. Only if …
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1
vote
Accepted
Electron magnetic moment in coupled squared Dirac equation
The coupling to the electric field is there because of Lorentz invariance. A magnetic dipole aquires an electric dipole component when seen from a moving frame. Note that the expectations $\psi^\d …
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1
vote
Is the scalar field in the Yukawa interaction real or complex?
The current $\bar\psi \gamma^\mu \psi$ will be equal to zero if $\psi$ is a Majorana fermion. This condition is the fermion analogue of being "real."
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0
votes
How to write a naive Dirac matrix for Lattice QCD?
On a 4d cubic lattice, the naive Dirac action just has the usual 4-by-4 $\gamma_0$ matrix on the time-direction links and the 4-by-4 $\gamma_1$ on the $x$-direction links, etc. The gamma's talk only …
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