Ross Young, Physics Division, Argonne National Laboratory
Strange quark currents in the electromagnetic structure of the nucleon
Physics Division Colloquium - 5 December 2008

The minimal content of the nucleon described by quantum chromodynamics (QCD) is merely three quarks. For many years now, deep inelastic scattering measurements have observed an abundance of quark-antiquark (q-qbar) pairs, representing a clear signature beyond the minimal three-quark picture. At more modest energies, it is largely unknown what role these quark-antiquark pairs play in the bound-state structure of the nucleon. As the lightest quark flavor outside the minimal three quarks, the strange quark provides the cleanest measure of the dynamics of q-qbar pairs in the nucleon. Here we report on the latest advances in parity-violating electron scattering measurements which have for the first time provided a direct measurement of electromagnetic currents carried by strange quarks. We also outline a recent theoretical determination based on lattice-QCD and compare this analysis with the current experimental status. We will conclude with an outlook on the future of the parity-violating experimental program.

ANL Physics Division Colloquium Schedule