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For the Public - High Energy Physics Tour

Quantum Chromodynamics (QCD)

We learn in elementary school or middle school that there are two types of electric charge: positive, like protons, and negative, like electrons. We also learn that opposite chrages attract each other, while similar charges repel one another. With this knowledge, we then learn that atoms, which all of us are made of, have electrons circling a positivvely charged nucleus made of protons and neutrons, which have no electric charge. This is a nice, easy model to picture, and most early science classes will leave it at that. But do you see a potential problem with this model of an atom? If similar charges repel, how can the nucleus stay together? Shouldn't all those protons blow it apart?

The only way for a nucleus to stay together is if there is some other force that is stronger than the electrical repulsion. This force is called the strong nuclear force. The theory that explains whaat it is and how it works and behaves is now called quantum chromodynamics, or just QCD. It turns out that QCD is a very mathematical theory, but we will check out a few of its key ideas so we caan gain some insight as far as how the nucleus behaves as well as how the theory is used at CDF in order to make sense of the data it collects.

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last modified 7/19/2001   email CDF
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