Re: please help my confusion about particles and irreps.

In article <429F4C54.1010700@xxxxxxxxxxxx>,
Eugene Stefanovich <eugenev@xxxxxxxxxxxx> wrote:

> > I mean, in what sense is a quark a particle at low energies.
>
> I prefer to discuss more conventional particles as examples, e.g.,
> electrons, photons...

You can prefer to discuss regimes in which perturbation theory makes
sense all you want, but it's avoiding the issue. It's precisely in the
regimes where perturbation theory doesn't make sense that you have
problems.

> Quarks have not been directly observed
> experimentally, so there remains a chance that they are just
> mathematical artifacts.

You need to explain deep inelastic scattering where, at high energies,
quarks are observed to be particle-like because of asymptotic freedom.

> I also prefer to stay within boundaries
> of simple quantum electrodynamics. My knowledge rapidly fades
> away when you move to areas such as CFT, QCD, etc. I think that
> QED, which is mother of all quantum field theories, should be
> appropriate for discussion of the field/particle dilemma.

QED is special because the coupling is so small. Do any of your formulae
make sense with alpha=1? QED also is, in all likelihood, an incomplete
theory due to the existence of the Landau pole.

> Could we stay within QED, please?

No. If you want to talk about QFT, you have to talk about QFT.

Aaron

.

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