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arXiv · hep-ph/0310277

Single-Spin Polarization Effects and the Determination of Timelike Proton Form Factors

S. J. Brodsky·C. E. Carlson·J. R. Hiller·D. S. Hwang
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Abstract

We show that measurements of the proton's polarization in electron-positron annihilation to a proton-antiproton pair $e^+ e^- \to p \bar p$ strongly discriminate between the analytic forms of models which fit the proton form factors in the spacelike region. In particular, the single-spin asymmetry normal to the scattering plane measures the relative phase difference between the timelike $G_E$ and $G_M$ form factors. The expected proton polarization in the timelike region is large, of order of several tens of percent.

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S. J. Brodsky, C. E. Carlson, J. R. Hiller, D. S. Hwang. 2003-10-23. Single-Spin Polarization Effects and the Determination of Timelike Proton Form Factors. https://doi.org/10.1103/physrevd.69.054022

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