The OLYMPUS experiment will determine the multiple-photon exchange contribution to elastic lepton-proton scattering. The motivation for this experiment comes from an inconsistency in measurements of the proton electric-To-magnetic form factor ratio between the Rosenbluth separation and polarization techniques. It is expected that neglected multiple-photon exchange contributions to elastic lepton-proton scattering distort the extracted form factors and are the cause of this discrepancy. Determining the multiple-photon exchange contribution can be achieved by measuring the positron-proton to electron-proton elastic scattering cross section ratio. OLYMPUS was designed to measure this cross section ratio to better than 1% uncertainty for a wide range of four-momentum transfer and virtual photon polarization. The data for the ratio were taken in 2012 using 2.01 GeV electron and positron beams incident on a hydrogen target. The data analysis is currently underway with preliminary results expected by November 2015.
|Original language||English (US)|
|State||Published - 2015|
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