All Questions
Tagged with terminology quantum-field-theory
115
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Renormalization group equation, the Callan-Symanzik equation, and renormalization group flow
I am learning about the renormalization group and I am getting confused on some terminology.
For the massless $\phi^4$ theory the Callan-Symanzik equation is:
$$\big[ M \frac{\partial}{\partial M} + \...
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Are vacuum energy, zero point energy and vacuum fluctuations the same thing?
im confused about the relationship between these terms, my intuition tells me that vacuum energy and zero point energy are synonymous and that they are a consequence of vacuum fluctuations. But I ...
- 51
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What is the difference between wavefunction renormalization and field strength renormalization?
A while ago I asked a question asking what is field strength renormalization (What exactly is field strength renormalization?). I now have a better way of thinking about this, which is that it relates ...
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Contact terms in Schwinger-Dyson equation and Ward-identity
I am reading Weigand's notes for the derivation of Ward-identity.
The Second last paragraph on page 133, says the following statement
"The Schwinger-Dyson equation and the Ward-identity show ...
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What is the difference between quantum thermodynamics and nonequilibrium QFT?
I see a lot of books of Nonequilibrium QFT and they study the thermodynamics on quatum realms, but what is the difference about that and Quantum Thermodynamics? They study the same thing only with ...
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Explanation of Multiplet Shortening and Unitary Bounds in Supersymmetry (AdS/CFT): Algebraic Insights
I am currently studying this paper and I'm struggling to grasp the concepts of multiplet shortening and unitary bounds in the context of supersymmetry. I am specifically interested in obtaining a ...
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865
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Schrödinger equation in QFT
I’m studying QFT and I learnt that we didn’t change the Schrödinger equation into relativistic one but Klein-Gordon and Dirac equation are now the equation of motion of our fields operator.
But our ...
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4
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What exactly is field strength renormalization?
One thing I have not fully understood is what field strength renormalization is. In Peskin & Schroeder's book "An Introduction to Quantum Field Theory" (Section 7.1) they introduce it as ...
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How to understand this decomposition of the spectrum of a QFT
The reference for this question is the following set of notes on the conformal bootstrap, section 1.2.2. Suppose we have a quantum field theory with symmetry algebra $\mathfrak g$ and spectrum $\...
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The difference between operator condition, differential condition and algebraic condition?
It is well known that the gauge potential $A_\mu=(\phi,-\vec{A})$ has gauge symmetry and one could impose Lorenz and Coulomb gauge simultaneously to it to eliminate redundant degrees of freedom. In ...
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What are Wilson Coefficients?
I have seen this terminology in several papers but I haven't managed to find an explanation of what they actually are. I understand that they are related to effective field theory.
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Quasifree states vs Gaussian states
Does anyone know the origin of the term "quasifree states" in algebraic formulation of QFT? As far as I am aware of, the definition is effectively equivalent to Gaussian states centred at ...
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NLO and NLL difference [duplicate]
The next-to-leading order (NLO) Feynman diagram is the next leading process having more vertices than the tree-level diagram, but what is next-to-leading-logarithm (NLL)?
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372
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"Classical field configuration" - QFT
I often encounter the term "classical field configuration" in the scope of QFT, but I have a hard time interpreting what it really means.
If I understood it correctly, then a general field ...
- 447
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Why do excitations not exist in non-quantum fields? [duplicate]
In my understanding, where the value of a quantum field [i.e. a field with discrete values] is 0 it is said to be in the ground state, and where it is not 0 it is said to be an excitation. Why do we ...
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