Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering

Download or read book Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering written by and published by . This book was released on 2007 with total page 2301 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely-polarized 3 GeV electrons from unpolarized protons at Q^2 values of 0.15 and 0.25 (GeV/c)^2 with results of A_n = -4.06 +- 0.99(stat) +- 0.63(syst) and A_n = -4.82 +- 1.87(stat) +- 0.98(syst) ppm. These results are inconsistent with calculations solely using the elastic nucleon intermediate state, and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A_n provides a direct probe of the imaginary component of the two-photon exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.