Structure of Matter

Color Charge


So one had to explain why one saw only those combinations of quarks and antiquarks that had integer charge, and why no one ever saw a q, qq, qqqbar, or countless other combinations.


Just like the combination of red and blue gives purple, the combination of certain colors give white. One example is the combination of red, green and blue.


Gell-Mann and others thought that the answer had to lie in the nature of forces between quarks. This force is the so-called "strong" force, and the new charges that feel the force are called "color" charges, even though they have nothing to do with ordinary colors. They proposed that quarks can have three color charges. This type of charge was called "color" because certain combinations of quark colors would be "neutral" in the sense that three ordinary colors can yield white, a neutral color.

Only particles that are color neutral can exist, which is why only qqq and q q-bar are seen.

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