We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12≤Q2≤1.0 GeV2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions to the currents of the proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate nonzero, Q2 dependent, strange-quark contributions and provide new information beyond that obtained in previous experiments.
Physical review letters
Armstrong, D. S.; Biselli, Angela; and G0 Collaboration, "Strange-quark contributions to parity-violating asymmetries in the forward G0 electron-proton scattering experiment" (2005). Physics Faculty Publications. 16.
Armstrong, D. S., et al. "Strange-quark contributions to parity-violating asymmetries in the forward G0 electron-proton scattering experiment." Physical review letters 95.9 (2005): 092001. DOI: 10.1103/PhysRevLett.95.092001