Strange Quarks in the Proton
It is even more significant that the experimental measurement is in excellent agreement with a recent theoretical determination by an international team of physicists from the University of Adelaide, DOE's Thomas Jefferson National Accelerator Facility and the University of Edinburgh. The team applied a unique combination of cutting-edge numerical and analytic approaches to QCD to precisely calculate the strange quark contribution to the charge radius to be less than 1% of the total. (Their earlier result for the magnetic moment was even more precise, at a mere 0.6% of the proton moment.) One of the consequences of the calculation is that the strange quark can never stray too far from its anti-particle. The paper is published in Physical Review Letters.