Recent content by HomogenousCow

I've been doing some research on the topic of radiation reaction force/self force in classical electrodynamics and although there are some discussions on the internet I would like direct answers to these following questions: Is there a rigorous and universally accepted treatment of radiation...

In one particle quantum mechanics we have a system described by a state space and a number of observables like ##\hat{q}##, ##\hat{p}##, ##\hat{S_z}## etc. At any point in time the system is in some state ##|\psi\rangle## and the wavefunction is given by ##\langle q|\psi\rangle## where...

Is this true? I thought one could write down non-local field theories that were still lorentz invariant.

You're right, the state ##\psi(x)|0\rangle## represents a specific superposition of localized fermion states which is exactly why the LSZ theorem for fermions includes factors of ##\overline{u}_{s}(k)## and ##\overline{v}_{s}(k)## to project out your desired states. It's probably better to think...

Let's say that we have a one-particle Hamiltonian that admits only a continuous spectrum of eigenvalues ##E(k)=\alpha k^2## parameterized by asymptotic momentum ##\mathbf{k}## (assuming the eigenfunctions become planewaves far from the origin), would the partition function then be $$Z=\int...

Is the ##SU(2)_L## part of the SM asymptotically free like a typical non-Abelian gauge theory? I've been made to understand that confinement does not occur for ##SU(2)_L## because the spontaneous symmetry breaking scale is above the confinement scale, however I can't find any information on...

Could you elaborate on this? Sounds interesting but I don't fully understand the argument.

Back when the SM was being developed renormalizability was a lot more important to theorists so they picked only renormalizable terms for the Lagrangian, and the quartic self interaction is the only renormalizable way to have spontaneous symmetry breaking for the Higgs field. Why did this...

The unbound hydrogen states are briefly mentioned on page 231 of these notes.

Was experimenting with numerically inverting functions in mathematica and decided to use it to plot the heat capacity of a free bose gas: Isn't it kind of odd how the heat capacity exceeds the classical value of 3/2 around the phase transition?

This text by Maggiore is pretty great.

$$P_{12}H(1,2)\psi(12) = P_{12}H(1,2){P_{12}}^\dagger P_{12}\psi(1,2) = H(2,1)\psi(2,1)$$ using ##P_{12}^2 = I## and ##{P_{12}}^\dagger = P_{12}##.

1) You end up with meaningless expressions since the ##(E_1 - E_2)^{-1}## factors diverge. 2) No, the necessity to choose the "right" basis only arises in perturbation theory because we're looking for a power series in terms of ##\lambda## which cannot approximate jump-discontinuities.

A source function generates a coherent state in QFT the same way as it does in classical field theory, see my response in this thread https://www.physicsforums.com/threads/quantization-of-the-electromagnetic-field.1010889/#post-6584753.

If the elevator's acceleration exceeds ##g## then indeed objects inside will fly up towards the ceiling, however below ##g## objects inside are still bound to the floor of the elevator by gravity.