Unanswered Questions

Beyond the Proton, Neutron, and Electron

What are the masses of the quarks and leptons?

Because quarks can’t be separated their masses can only be found by using one or more theories to calculate them. The masses of the charged leptons can be measured to high precision. In the Standard Model neutrinos are all massless, but recent experimental results demand that they have mass.

Masses are given in a unit that is energy divided by the speed of light squared based on Einstein’s E = mc2.


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