Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 47: Hadron Structure and Spectroscopy II

HK 47.6: Talk

Wednesday, March 18, 2009, 15:15–15:30, H-ZO 30

The strangeness of the proton measured by the G0 parity violation experiment at Jefferson Laboratory — •Jean-sebastien Real — LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble

The strangeness content of the proton is related to the sea quarks contribution to the nucleon properties, as the spin, the mass or the current. In this context, the parity violation experiments measure this contribution to the electromagnetic (EM) current of the proton, through the strange electric and magnetic form factors. The full access to these quantities requires the measurement of weak form factors of the proton. They can be accessed by measuring the asymmetry in elastic scattering of longitudinally polarized electron on hydrogen and deuterium at two different electron angles (forward and backward). The parity violation asymmetry is of the order of 10-5 and is measured at 10-6 level of accuracy. The G0 experimental setup will be described in the two configurations and the results will be presents. The forward G0 experiment provides a linear combination of the electric and magnetic strange quark contribution over a wide kinematical range. The backward G0 experiment will provide the separate electric and magnetic strange quarks contribution at two kinematics Q2 ~ 0.63 and 0.23 (GeV/c)2.