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I was just thinking about Einstein's famous $E=mc^2$, and how it equates energy to mass and mass to energy. I was wondering, if the charge is a measure of energy, then if a particle accepts a charge does it gain mass?

Qmechanic
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August H
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    Charge is not a measure of energy. Charge is a measure of how strongly coupled a particle is to a field. – dA-Ve Feb 10 '20 at 00:45
  • Hi, dear August! How can an elementary particle take up charge without staying the same? A composed particle, like a (neutral) neutron, can be converted to a (charged) proton. Are you talking about elementary particles? – Deschele Schilder Feb 10 '20 at 08:47
  • Yes, it is called self-mass: https://arxiv.org/abs/1807.05338 – safesphere Feb 10 '20 at 08:48
  • That's an integral part of the particle (if it's elementary). If the particle is point-like the charge is compressed to a point. This only goes to show that the charge comes in chunks and is not continuous. – Deschele Schilder Feb 10 '20 at 08:53
  • Compared to what? An elementary particle cannot accept a charge. – Qmechanic Feb 10 '20 at 09:43
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    The strong interaction (color charge) DOES contribute mass to quarks under the general paradigm of dynamical chiral symmetry breaking even without the Higgs mechanism. Actually, the ambitious (and failed) attempt of technicolor is QCD on steroid which is meant to generate all the masses from techicharge and replace the Higgs mechanism. – MadMax Feb 10 '20 at 17:37
  • @Qmechanic “An elementary particle cannot accept a charge.” - A charge is a quantum number that a neutrino can accept as a W boson to become an electron. An elementary particle is defined by its quantum numbers. The only quantum number different between a neutrino and electron is the charge. So why couldn’t we say that a neutrino is an electron without its charge? – safesphere Feb 13 '20 at 06:36

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I suppose what you want to ask here is "does charge contribute to the mass of a particle?" and, if one is referring to elementary, fundamental particles like the electron, then I would think it is not possible to answer this scientifically.

The reason is rather simple: in order to be able to determine if charge contributes in the way you're thinking to an electron's mass, we'd need to be able to strip an electron of its charge, so as to have an uncharged version to perform the comparison of masses against. That, in turn, would mean there would have to be a particle identical in every respect (except perhaps mass) to the electron, only missing its charge, i.e. a "neutral electron".

Otherwise, if we're comparing an electron against some other neutral particle (like neutrinos) it isn't very useful, because such are different particles in many other ways, and hence they do not constitute a suitable experimental control as we have not isolated the independent variable (charge) for which we seek to observe a causal relationship between changes in it and changes in the dependent variable (mass).

However, as far as we can tell, such "neutral electrons", identical in every way but charge to their charged versions, don't exist. Therefore, we cannot remove the confounding variables, and so there is no scientific experimental study that can be done to assess an answer to this question.

The_Sympathizer
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  • I am not convinced. In your hypotheticals you are comparing “charge” with “no charge”. How about comparing “charge” with “more charge”? How would the mass of an electron as well as mass difference between proton and neutron (or between $\pi^\pm$ and $\pi^0$) change if the value of elementary charge increased? – A.V.S. Feb 10 '20 at 04:31
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    @A.V.S. Again, though, we also don't have "electrons" identical in all other ways to the ones we have, save for having more charge, either. – The_Sympathizer Feb 10 '20 at 04:43
  • In what “many other ways” a neutrino is different from an electron? A neutrino is an electron with no charge, is it not? – safesphere Feb 10 '20 at 08:26
  • That's not true. An electron is not the same as an uncharged electron. Especially when one looks at it through the rishon spectacles. See https://en.wikipedia.org/wiki/Rishon_model. And besides, if the electron had no charge, why would the mass get close to zero. Because of the energy stored in the "compressed" charge of the electron. – Deschele Schilder Feb 10 '20 at 08:40
  • Again, though, we also don't have "electrons" … Electrons do not exist without some conceptual framework allowing us to discuss their properties. But once we have a framework of sufficient formal power (such as Standard model) we immediately gain ability to consider alternative models with varying properties such as values of charge etc. … – A.V.S. Feb 10 '20 at 15:33
  • … Also, we do not know the charge of an electron, experimentally we can only know the range of possible values, so any quantitative statement about electron charge has such “theoretical” electrons with more or less charge built in. – A.V.S. Feb 10 '20 at 15:35
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If you are asking about color charge, then the answer is no, gluons are known to be massless as per the SM, and they do carry color charge.

If you are asking about EM charge, then the answer is still no, but the explanation is not so simple. According to the SM, at some point, before electroweak symmetry breaking, charged particles were actually massless.

Another take on this issue is that Standard Model particles (and in particular charged ones) were massless before electrosymmetric breaking (at least disregarding other mechanisms of mass generation).

Massless charged particles

But in our world currently, massless charged particles are theoretically not possible, because they would make the matter everything is made up of unstable.

If there were massless charged particles, the electron and positron would become unstable - one problem - and the fine-structure constant would run to α=0 at very long distances - another problem, and it obviously doesn't. So massless charged particles are theoretically impossible in our world - assuming that we empirically know some things such as the fact that there is a limiting Coulomb force at long distances.

So this makes it impossible to compare the same type of particle and see if the charged version has more mass, since we do not know of any massless charged particles in the SM.

Now you could try to find some connection between the net EM charge a particle possesses and try to see if that particle has more mass then the ones with less net EM charge, but again, the down quark has more mass and less net EM charge then the electron, so the answer to your question is no.

Árpád Szendrei
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The $E=mc^2$ formula applies only for high velocities and is not relevant in describing masses. The length of four vectors of particles (and the added fourvectors of systems of particles) is called an invariant mass and does not change under Lorentz transformations.

In the classical picture:

A negatively charged mass has extra electrons to the atomic ones, so yes it will have a larger mass.

A positively charged mass has fewer electrons than needed for the atoms it has, so it will have a smaller mass.

In the quantum mechanical frame the elementary particles have charge as a number that identifies an elementary particle together with the other quantum numbers. Elementary particles are not composite, so the charge cannot be considered independent of the particle. All macroscopic matter is made up of elementary particles.

So in mainstream physics there is no way charge can be separated from the particle itself to be assigned an extra mass. It might be possible in models assuming that elementary particles are composite but I doubt it..

anna v
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  • The rishon model is a good candidate.https://en.wikipedia.org/wiki/Rishon_model – Deschele Schilder Feb 10 '20 at 08:56
  • It's as beautiful as the quark-model once was (is)! In this model (only 2 elementary particles!) charge can't be separated from the rishons either. We need "just" higher energies to investigate or look for implications. – Deschele Schilder Feb 10 '20 at 09:04