We now know from experiments such as CDF that there are hundreds of small, subatomic particles that can exist in nature. This is quite different than the simple picture taught in schools where the world is a more simple place with only protons, electrons, and neutrons. As all these other particles were being discovered over the last fifty years, physicists began think that nature could not be such a confusing and complex place. Scientists like to try and think about things in as simple a picture as possible, and it was becoming hard to believe that the structure of matter could be as complicated as it now appeared, with a large zoo of particles.

As physicists began to study the properties of all the particles they were finding, certain patterns began to appear. After many years, new ideas developed that attempted to make some sense out of the particle zoo. One model began to stand out as something that might just work: the quark model. This model of matter made use of three new particles called up, down and strange quarks, and in the 1960s could explain the properties of the particles that were known. Since then, three more quarks have been added to the model, making a total of six quarks (the second group of three quarks have the names charm, bottom and top). Let's take a look at some of the properties of quarks as well as how they can combine to make the variety of particles we find in nature.

Standard Model >

Return to HEP Main Page

Suggestions or questions? Please contact mfv@fnald.fnal.gov