Strange Matters

Department Of Energy, Washington, D.C. — The result from a years-long effort at DOE’s Jefferson Lab (known as the G-Zero experiment) to measure strange matter in the proton has revealed that strange matter doesn’t magnetize the proton or distort its charge distribution all that much. The effect is surprising small, since many of the early theoretical calculations suggested the possibility of larger values.

The proton’s main building blocks are up and down quarks, which are bound together by the strong force. The strong force energy inside protons also gives rise to a “sea” of quark pairs that bubble up out of the strong force energy and almost immediately melt away again. Pairs of up quarks and pairs of down quarks are the most likely to appear briefly in this sea. The next-heaviest quarks, strange quarks, are also thought to be present.

G-Zero scientists set out to measure what effect the temporary strange quarks had on the proton’s structure. The experiment successfully measured the influence that strange quarks exert on the electric and magnetic fields—seen as the distribution of charge and magnetization inside the proton. Experimenters found that the strange quark influence was small—amounting to less than 10% of the proton’s charge distribution and magnetization.