Quarks, gluons and jets.

(From Guardian Unlimited)

In July we (ATLAS ) released a preliminary version of our first jet cross section measurement, and showed it at the International Conference on High Energy Physics (ICHEP ) in Paris. Today we submitted the final version of this measurement to the European Physical Journal and to the archive .

"Cross section" in this context is basically a probability. If you fire two footballs at each other, they have a bigger cross-sectional area than two snooker balls, so they are more likely to hit each other. A "jet cross section" is a measure of how likely we are to see jets when we fire two protons at each other.

Jets are what quarks and …