# Tag Info

1

What is an ECE engineer, an electronic-computer-engineering engineer? Indeed Classical Electrodynamics is only an approximation to Quantum Electrodynamics. If you just want to get a taste, I would suggest reading Feynman's QED: The Strange Theory of Light and Matter. It describes the theory quite nicely without too much maths. If you want to learn full ...

6

Yes, you would have to introduce another gauge field. For example in the Standard Model there is gauge invariance under $SU(3)\times SU(2) \times U(1)$, and so there are three gauge fields: the gluons, the $W^\pm, Z$ weak gauge bosons and the photon. In general terms, it is simpler to argue like this: if you have gauge invariance under a Lie group $G$, the ...

0

Just another hint for Enos Oye: 2 u know that the photon emission in a resonant cavity can be greatly reduced by changing the size of the cavity? This suggests that the photon already knows when/where it'll meet a receiver.. its receiver

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Indeed, the two effects are very much related! I don't know how your background is, so let me start by defining the four-vector $x^\mu=(t,x,y,z)=(t,\vec{x})$ such that $x^0=t$ and $x_i=x,y,z$ for $i=1,2,3$. (Note that it is convention that greek indices run from $0$ to $3$ (space-time) while latin indices run from $1$ to $3$ (space only). Summation over ...

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I think because the wavefunctions are required to be normalized so that $\psi^{*}\psi$ represents the probability or probability density of finding the particle, so their amplitude are not allowed to scale arbitrarily. That's why the gauge field can only be real.

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The additional correction to the magnetic moment of the electron, aptly called the 'anomalous magnetic moment,' arises from a one loop Feynman diagram calculation in quantum electrodynamics. To be specific, the Landé $g$ factor is given by, $$g=2[1+F_2(0)]$$ where $F_2$ is a 'form factor.' The electron vertex scattering amplitude is given by, ...

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The Coulomb logarithm is a heuristic cutoff. For length scales beyond the Debye radius, electrons in a plasma see a smoothed electric field, not the $1/r$ potential of the neighboring electrons. Hence, when computing two-body scattering, for electrons with an impact parameter too far out, that particular charge will be screened and cut off. Thus, in any ...

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Zeta function regularization is used in other fields, and even in pure mathematics to obtain finite answers from otherwise divergent integrals. In bosonic string theory, the mass of states in lightcone gauge is, $$M^2 = \frac{4}{\alpha'} \left[ \sum_{n>0} \alpha^{i}_{-n}\alpha^{i}_n + \frac{D-2}{2}\left( \sum_{n>0} n\right) \right]$$ where $\alpha'$ ...

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