| The Columbia Encyclopedia, Sixth Edition. 2001-07. |
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| Elementary Particles (table) |
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| | | Leptons | | Particle | Symbol | Mass (MeV/c2) | Electric Charge | | electron | e- | 0.511 | -1 | | muon | mu- | 105.7 | -1 | | tau |  | 1784.1 | -1 | | electron neutrino | nue | <7.3×10-6 | 0 | | muon neutrino | numu | <0.27 | 0 | | tau neutrino | nu | <35 | 0 | | | | Quarks1 | | down | d | 5–15 | -1/3 | | up | u | 2–8 | 2/3 | | strange | s | 100–300 | -1/3 | | charm | c | 1300–1700 | 2/3 | | bottom | b | 4700–5300 | -1/3 | | top | t | >91,000 | 2/3 | | | | Gauge Bosons | | photon | gamma | 0 | 0 | | gluon | g | 0 | 0 | | W-boson | W | 80,200 | 1 | | Z-boson | Z | 91,170 | 0 | | | | Some Sample Hadrons | | Particle | Symbol | Mass (MeV/c2) | Electric Charge | Quark Content | | positive pion |  + | 139.6 | 1 | ud | | positive kaon | K+ | 493.7 | 1 | us | | proton | p | 938.3 | 1 | uud | | neutron | n | 939.6 | 0 | udd | | lambda | Lambda | 1115.6 | 0 | uds |
| For each of these particles, except the photon, gluon, and Z-boson, there is an antiparticle with the same mass and opposite charge. In most cases the antiparticle is denoted by an overbar over the particle symbol (e.g., the symbol for the antiproton is p. | | 1 Because quarks cannot be isolated, the masses given for them are approximate. |
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| | | The Columbia Encyclopedia, Sixth Edition. Copyright © 2007 Columbia University Press. |
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