Why is it that there exists a classical macroscopic field of photons and gravitons but not that of $Z, W^{\pm}$ bosons, gluons or Higgs boson?


1 Answer 1


There are slightly different answers for each particle type.

  • Macroscopic photon and graviton fields can exist because these forces are long-ranged, which is directly related to the force carriers being massless. The $W$ and $Z$ bosons are extremely massive, so they're very short ranged and we can't see their effects on a macroscopic scale.
  • Another problem is that classical macroscopic fields arise from quantum fields through coherent states, which require many particles. Since the $W$ and $Z$ are so heavy, this is impossible at everyday energies.
  • Gluons are massless, but there's no macroscopic gluon field because the strong interaction becomes stronger at low energies, strong enough to bind color charged particles together. As a result, every macroscopic object we see has exactly zero color charge, so we see no gluon field.
  • The Higgs boson is massive, but there is a macroscopic Higgs field, in the sense that the field value is nonzero due to spontaneous symmetry breaking. You are, in some sense, measuring this field every time you measure the mass of an elementary particle. However, you can't make macroscopic waves in the Higgs field (i.e. excitations about the constant field value) for the same reason as the $W$ and $Z$.
  • $\begingroup$ Nice answer - the only thing lacking would be a mention that the "bind" described in the third paragraph (confinement) is qualitatively different from the bound that e.g. an electron and a proton have through the electromagnetic force. $\endgroup$
    – ACuriousMind
    Oct 20, 2016 at 17:41
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    $\begingroup$ While gluons have no rest mass, there is evidence that gluons acquire mass dynamically in the infrared limit and are only truly without mass in the ultraviolet limits (of course, gluons always have mass-energy). See this 2011 paper on point: iopscience.iop.org/article/10.1088/0954-3899/38/4/045003/… $\endgroup$
    – ohwilleke
    Oct 20, 2016 at 18:11
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    $\begingroup$ "gluons acquire mass dynamically in the infrared limit" Whoa! $\endgroup$ Oct 20, 2016 at 18:44
  • $\begingroup$ I'm not sure you can still talk about gluons in the infrared limit. The gluons appear in the Lagrangian description in the ultraviolet limit only, and if you want to write an effective theory at low energy, the "particles", ie the degrees of freedom that appear in the effective Lagrangian, have nothing to do with gluons. $\endgroup$
    – Antoine
    Oct 25, 2016 at 19:39
  • $\begingroup$ Also note that photons and gravitons are stable, while W, Z and Higgs are extremely short-lived. $\endgroup$
    – kkumer
    Oct 25, 2016 at 19:42

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