Physics Questions People Ask Fermilab
Charge, Spin and Mass of Fundamental Particles
Hello, I've been searching the web for some kind of list of the rest mass, charge and spin of the most fundamental particles; as I understand these should include 6 quark types, 6 lepton types and 5 types of force-carrying particles (photon, gluon, W, Z, graviton). Also I am wondering if the electron is "colorless" in the same way as a proton is, as the proton is built up out of particles with color and and electron is not. I would be very grateful for any suggestions.
P.S. if this is the wrong place to ask my question please tell me where I should ask it.
You wrote: I've been searching the web for some kind of list of the rest mass, charge and spin of the most fundamental particles; as I understand these should include 6 quark types, 6 lepton types and 5 types of force-carrying particles (photon, gluon, W, Z, graviton).
Yes, you got it all right. The graviton, though, is still a hypothetical particle. Since all other forces are transmitted by force-carrying particles, physicists think that there is also a particle for gravity.
Every particle also has an antiparticle. In the case of photon, gluon, Z, and graviton the antiparticle is identical to the particle. The W is the only force-carrying particle with electric charge. So the W with charge +1 is the antiparticle of the W with charge -1.
The quarks and leptons all have spin 1/2. All force-carrying particles have spin 1, except for the hypothetical graviton. There is no consistent theory for gravitons yet, but theorists expect the graviton to be spin 2.
All further information you requested can be found at:
If you want all scientific details on data you can also look at:
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Regarding your color question: To our knowledge the electron is a fundamental particle, not a composite. It is truly colorless. Experiments show that the electron is smaller than 10**(-23) meter, an unbelievable small number: 0.000 (total of 22 zeros after the period) 0001 m.
If the electron has substructure, it must be even smaller than that. There is absolutely no evidence for that. Physicists even speak of the electron being a point-like particle, having no extension at all.
The proton, as you correctly mentioned, is build up of quarks. The proton is colorless, the quarks are not. Quarks cannot exist by themselves: They always form colorless objects, for example protons, neutrons and pions.
Theproton has a diameter of 10**(-15) meter, and the quarks are smaller than 10**(-19) meter. Physicists actually believe that quarks are point-like particles, too. As we built better and better "microscopes" (accelerators) we may or may not confirm this thinking. After all, people originally thought of the proton not having any substructure.
Please let me know if you need more information.
Kurt Riesselmann Fermilab Physicist, Public Affairs
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