Quantum-ElectroDynamics (QED) is the quantum field theory believed to describe the electromagnetic interaction (and with some extension the weak nuclear force).

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How sketch the renormalization group flows in the $(\lambda, e^2)$ plan for scalar QED?

I have obtained beta functions of renormalization group for scalar QED: $$ \beta (e) = \frac{e^3}{48 \pi^2} $$ $$ \beta(\lambda) = \frac{1}{24\pi^2}(5\lambda^2 - 18e^2\lambda + 54 e^4) $$ which give ...
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Deriving Coulomb's law from quantum electrodynamics [duplicate]

Is it possible to derive the Coulomb's law using the principles of quantum electrodynamics? How?
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Integration for quantum amplitude of the coupling between two molecules

I am trying to solve following expression for quantum amplitude of coupling between two molecules, (arriving from the second order perubation) $$\frac{1}{p}\nabla_{j}\int e^{ipR\cos(\theta)} dT=i\int ...
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Massive vector field in curved spacetime

Setup Consider a massive vector field in anti-de Sitter space AdS$_{d+1}$ with metric $$ ds^2=\frac{1}{z^2}\left(dx_\mu dx^\mu+dz^2\right) $$ where $dx_\mu dx^\mu$ is the line element in d+1 ...
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Associated photon field of a two state system

Given the time-dependent density matrix $\rho(t)$ of a driven two-state system $\mathcal{S}$. How do I calculate the time-dependent quantized photon field that would be generated by transitions in ...
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The Schwinger Limit and the Breit-Wheeler Process

The Breit-Wheeler process requires a two photon system to have a total energy of at least twice the rest mass of an electron, which is determined by the frequencies of the photons. The Schwinger ...
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Feynman Diagram in QED non relativistic limit

I am following Peskin to read Feynman diagram. But in this image given, he used the non-relativistic limit to write the incoming fermion gamma mu product. How did he get it? Any explanations in ...
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What do the tensors here equal to?

In the process $$e^+e^- \rightarrow \gamma \gamma$$ for which the amplitude can be written as: $M= \epsilon^*_{1\nu}\epsilon^*_{2\mu}(A^{\mu\nu}+\tilde{A}^{\mu\nu})$, where $\epsilon_i$ is the ...
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Is there an expression for field charge analogous to field mass?

In electrodynamics, it is possible to derive an expression for the field momentum for a given moving charge distribution (e.g. a sphere with uniform velocity) and from that infer an "electromagnetic ...
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Is the elementary charge really a constant of nature? - Accuracy of QED

There are a couple of natural constants; examples are Planck's constant or the Speed of light in vacuum. The elementary Charge is the coupling factor to all Kind of electromagnetic interactions; this ...
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Physical meaning of the coupling matrix in Fermi golden rule

I am calculating the energy transfer rate using Fermi golden rule where the coupling matrix $M$ is obtained using second order pertubation method. $$ \Gamma_{tran}=\frac{2\pi}{\hslash}|M|^{2}\rho$$ ...
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Correction of arrow of particle direction

I have seen a stamp of Richard Feynman where Feynman hold the famous Feynman diagram. But is there any problem of the direction of arrow?
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How the experimental charge $e=1.60217657 × 10^{-19} C$ has precisely this value?

The coupling constant that we measured in "arbitrarily" low energy is $e=1.60217657 × 10^{-19} C$. How this is presented in Renormalization Group flow in charge coupling space? Why the action of the ...
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Converting mode expansion to an integral in an Cavity

Assuming the cavity length is large, can we convert the summation over cavity EM modes to an integral form? In that case is it reasonable to do below conversion? p is the mode number.
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If 2 photons collided head on, what would happen? [duplicate]

If 2 photons, in perfect synch (frequency, amplitude, etc. were all equal) and they collided head on, what would happen? Would they pass right through each other? Would they interfere, then go back to ...
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Electro-magnetic wave propagation in vacum

I was wondering what will the EM wave propagation including virtual particle pairs existence look like. When electric field face virtual pair it should make the lowest state energy the most ...
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What are the “two surfaces” in QED's reflection by two surfaces

When Feynman refers to the "top surface" and "bottom surface" probabilities when explaining QED, is he referring to the probability of the photons reaching the top of the object and the bottom of the ...
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QED: what is the relationship between emission and absorbtion spectrums? (and why do plants absorb blue light and emit green light..)

I'm interested in this because of photosynthesis, but hte question is general. I'm looking for a QED explanation. A lot of the explanations talk about light shining on a plant getting aborbed, ...
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Photo-excitation in terms of particle physics [duplicate]

How does a photon couple to an electron during an excitation/de-excitation process in an atom? My current understanding is rather limited especially when considering types of fundamental forces and ...
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Can the granular quantum nature of light be used to engineer a maroscopic optical phenomena?

Today we have optical metamaterials and metasurfaces: materials and surfaces that are made of unit cells with an approximate size of tens of nanometers, that can that interact with light and can have ...
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Which renormalisation techniques are available for 3+1 QED?

I hope my question is not too naive, but I would like to know what are the available renormalisation techniques for 3+1 QED. I have read a bit about Pauli-Villars, but I am wondering if there are ...
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64 views

Commutation of field and atomic ladder operators in the Dicke model

Consider the Dicke model, whose Hamiltonian is (in the rotating wave approximation) \begin{equation} \hat H=\omega_c \hat a^\dagger \hat a+\omega_0 \hat \sigma_z + g(\hat a^\dagger \hat \sigma + \hat ...
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How is 2D spectroscopy able to show quantum coherent transport through networks?

For wave-like (quantum coherent) energy transfer in networks (eg. propagation of excitation in photosynthetic protein complexes of algae or FMO complex in plants) 2D electronic (photon echo?) ...
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156 views

How positron and electron annihilate forming photons? [duplicate]

Electron is a particle with momentum $p$ and it spins up. Positron is its antiparticle having momentum $-p$ and it spins down. "A positron is an electron travelling backwards in time" said by Feynman. ...
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Heisenberg approach of Quantum Electrodynamics

I am reading the book of Gunar Kallen "Quantum Electrodynamics" and in the Chapter VI he study the Vacuum polarization. He computes the experimental observable current ...
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Is the image formed at the retina messy?

The following passage has been extracted from Newton's book Opticks: ...So if PR [in Fig.at the top] represent any Object without Doors, and AB be a Lens placed at a hole in the Window-shut ...
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Using local U(1) Transformation to solve Problem in Path Integral [duplicate]

When we develop photon path integral, we assume that the current is always conserved. But if we consider interaction between electron/positron and photon, the Noether current is conserved only when ...
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Finding interaction Hamiltonian for nano particles

I am studying Quantum electrodynamics (QED) and the core part of this theory is the light-matter interaction (quantized light and matter). I referred many papers and books (Molecular quantum ...
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QED Laser Reflection Mirror Expirment

Feynman in his famous lectures in NZ, talked about an experiment with a reflection of a light from a "back" mirror with stripes on it I tried to find a video of such an experiment, but with no ...
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Macroscopic Forces from QED

In QED the carrier for electromagnetic interaction is a photon, while macroscopic forces are due to electromagnetic interaction (by macroscopic forces I mean: normal force, object collision, friction ...
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Mathematical formalism to include wave and particle perspectives of light

Does the exist any mathematical formalism (model) describing the behavior of light and incorporating its particle character (divisibility, quantization) and wave character? (i.e. quantized wave model) ...
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Quantum frequency vs classical frequency and Energy dependence

I recently realized what seems to be a contradiction in what is called "frequency" for light, and would enjoy some clarification of some more educated mind on the matter, thanking you in advance for ...
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301 views

Probability of absorption and emission of photons

Suppose you have a single electron in a box, and you shoot a single photon at it. How does one calculate the probability that the photon will be absorbed and the particle excited? Or that the photon ...
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Does electron field exist?

We know, that one-particle states can be earned from relativistic fields, which can be interpreted as functions determined on Minkowski space-time. Field must satisfy some conditions, by which we ...
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The electron and classical dynamics

Can I use Newtonian laws of dynamics and kinematics applied to electrons (like $F = ma$ and $s = s_0 + v_0 t + at^2/2$)? If not, why not? I know that everything in principle behaves in a quantum ...
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Photon detection time in NMR rotating frame

I think of an NMR experiment, but with a single spin half nucleus initially set to the excited state. When the nucleus finally returns to its ground state, it will emit a photon. An observer in the ...
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A question on charge renormalization in QED

Let us work with charge renormalization in QED. Consider 2-point photon correlation function $\Pi_2(q^2)$ at one loop level. We normalize the coupling constant at $q^2=0$ (point of normalization). ...
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How many particles are created in the strong electromagnetic field?

Consider a vacuum of charged massless scalar field. Then the uniform and isotropic electric field $E$ is turned on for a time interval $\tau$. The question is, how many scalar particles are created? ...
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Why polarization vector $= (0,1,i,0)$?

I know from CED that one has e.g. polarization $$\vec{E}(z,t) = \begin{bmatrix} e_{x} \\ e_{y} \\ 0 \end{bmatrix} \; e^{i(kz - 2 \pi f t)}. $$ Why do Peskin&Schroeder define a polarization ...
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Coverage of Quantum Electrodynamics (QED) in introductory Quantum Field Theory (QFT) books [closed]

Which QFT books also cover QED? I am not very familiar with QED, so I am looking for QFT books which cover QED too (I know they cover Quantum Chromodynamics (QCD).).
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A thought experiment with Heisenberg's Uncertainty Principle [duplicate]

Possible Duplicate: Could the Heisenberg Uncertainty Principle turn out to be false? Thought Experiment Ponder, for a moment, if I had a cube with 10cm sides which I'll name The Box. By ...
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Derivative of effective action with respect to classical fields

I have some trouble with the effective action involving fermions. Consider the following effective action (QED): $$\varGamma = \int \mathrm{d}^4 x \left( j_\mu \mathcal{A}_\mu + \bar{\varPsi} \eta + ...
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Can a classical (or quantum) field, particularly the EMF, have a frame of reference?

I understand that a massless particle (such as a photon) cannot have a frame of reference. But the electromagnetic field does have mass; does it have a frame of reference? If so, I have a second ...
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QED photon propagator to one-loop order gets different answers

I'm a self-studying 14-year-old who has a passion for particle physics. I'm currently trying to calculate the QED photon propagator to one loop. However, in all the places I've looked, even with the ...