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Results tagged with quantum-field-theory
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user 358900
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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Relation between Mass of Gauge Bosons and Range of Force in Terms of Asymptotic Calculus
Of course. It's a bit complicated and model (the gauge group) dependent but ideally if the force carrying particle has mass $\mu$ then the potential it induces is:
$V(r) = \frac{-g^2}{4\pi} \frac{e^{- …
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External/Background Fields Meaning
(I'll work in the Euclidean for convenience)
In the path integral formulation of QFT given a field $\phi$, or a set of them if you want to, we have that the partition function is given by:
$$Z[J] = \i …
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Poincare invariance of the vacuum
A way to check if the two vacuums are matched is to calculate the Bogoliubov coefficients associated to your Poincarè transformation and check if each of the two vacuum is still devoid of modes when s …
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3
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Physics of vacuum expectation values in QFT
I have some trouble understanding what is the physical meaning of the vacuum expectation value (VEV) when applied in a QFT context.
Question: What is the physical meaning of a VEV?
I understand that i …
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Physics of vacuum expectation values in QFT
After doing some research i might have found an answer, i will post it hoping to help others and to see if someone disagree.
I will start stating that we have 2 different states regarding a field $\ha …
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Unruh particles
Your question is a bit misleading.
Unruh radiation is not about light radiation. Is about thermal radiation.
You need to have a field, for example a scalar one $\phi$. The field is full of modes. Now …
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Accepted
Hey there I'm a beginner in particle physics trying to "selfstudy" from online resources. I ...
I'm sorry to tell you this but you have understood actually nothing about the standard model. I have the impression that you just grasped the correlation between terms, not what they do mean, like one …
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Accepted
Are Higgs mechanism and SSB different phenomena?
The answer is yes to both your questions.
You can have SSB without the Higgs mechanism, but you cannot have the Highs mechanism without SSB. In fact, the Higgs mechanism is the SSB of a (local) gauge …
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Is spin a fundamental property of QFT?
Murray's answer is not true. His description is valid only for QFTs which possess the Lorentz invariance.
A totally generic QFT must not possess an a priori Lorentz symmetry.
The standard model is a v …
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Is unitarity intimately "connected" to symmetry?
Yes, since in Quantum Mechanics unitarity is a key concept. Every symmetry is related to a group of transformations, of elements T. Now the action of this elements on the rays of QM states must be im …
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Interacting QFTs and Virtual Particles
Short introduction to my understanding:
As far as i understand, virtual particles are usually defined to be the internal lines in Feynman Diagrams. But we know that those are just useful tools to calc …
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Understanding mathematically the promotion of field/observable to operator in QFT
When you promote a field to an operator what you are doing is promoting a field, ie a tensor-valued function on spacetime, to an object called an operator-valued distribution over spacetime.
This is a …
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Writing Einstein-Hilbert and Gravity-matter Hamiltonian in terms of creation/annihilation op...
As a starting point, gravity it's not a quantum theory so there is no annihilation/creation operators for gravity for the moment.
In the approach of canonically quantizing gravity you have to treat gr …
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Semiclassic limit of a QFT in Zinn-Justin
I am reading the Zinn-Justin book "Quantum Field Theory and Critical Phenomena" and i have come across a perplexing point.
Given the partition functional, in Euclidean QFT:
$$Z[J, \hbar] = \int d^N \p …
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Accepted
Propagator Terms for Different Types of Particle
The free propagator is derived from the kinetic term of your lagrangian. For the case of the Dirac equation the kinetic term is:
$\bar{\psi}(i\partial_\mu\gamma^\mu - m)\psi$
In Yang Mills theories, t …
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