Can a charged point particle ever have spin zero? If not why?

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    $\begingroup$ What exactly do you mean by point particle? only non composite particles? $\endgroup$ – hof_a Nov 16 '19 at 9:41
  • $\begingroup$ Well yeah I mean it's possible with a composite isn't it? $\endgroup$ – Derek Seabrooke Nov 16 '19 at 9:42
  • $\begingroup$ Then, atleast in the standard model, the answer is no, as the only fundamental spin zero particle is the higgs boson which has no electric charge. $\endgroup$ – hof_a Nov 16 '19 at 9:45
  • $\begingroup$ Is there something that prevents such a particle from existing? $\endgroup$ – Derek Seabrooke Nov 16 '19 at 9:47
  • $\begingroup$ In general I don't think so no, pions are for example charged spin zero particles. We don't need a fundamental charged spin zero particle, although I'm not completly sure if some symmetries of the theory would forbid it. $\endgroup$ – hof_a Nov 16 '19 at 9:58

Yes, there are charged spin zero particles namely the charged pions. However, they are not point particles but rather have a radius comparable to that of a proton. None of the mesons and hadrons are. Only the leptons, the photon, the hypothetical gravitons are point particles. I am not sure of the status of the Higgs boson.

  • $\begingroup$ The Higgs boson is in the particle table as a point particle en.wikipedia.org/wiki/Elementary_particle in the SU(3)xSU(2)xU(1) standard model $\endgroup$ – anna v Nov 16 '19 at 14:45
  • $\begingroup$ But it has electric charge 0. $\endgroup$ – lux Nov 17 '19 at 6:31
  • $\begingroup$ Similarly with alpha particles, which are "more composite" but has the benefit of being stable. It is also a point particle, as far as real physics is concerned, unless you're doing extremely high-precision spectroscopy of helium, or collision experiments at high (probably MeV) energies. $\endgroup$ – Emilio Pisanty Nov 17 '19 at 17:07
  • $\begingroup$ @EmilioPisanty The alpha particle has a radius of 3.6 fm, so it should not be called a point particle. However, the OP may have meant a subatomic particle when he wrote that. $\endgroup$ – my2cts Nov 17 '19 at 18:51
  • $\begingroup$ @my2cts The term "point particle" is silly to begin with - it depends on what physics you're interested in, and no particle can be conclusively shown to have no internal structure or zero radius - so it is pointless to litigate it. I agree that it's as much of a point particle as pions are (i.e., neither of them really is, but both for of them there are broad stretches of useful regimes where they can be considered to be), which is why it's weird to mention pions but not alphas. $\endgroup$ – Emilio Pisanty Nov 17 '19 at 19:02

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