# Proton elastic form factor ratios to $Q^2$=3.5 GeV$^2$ by polarization transfer

Abstract : The ratio of the proton elastic electromagnetic form factors, $G_{Ep}/G_{Mp}$, was obtained by measuring $P_{t}$ and $P_{\ell}$, the transverse and longitudinal recoil proton polarization components, respectively, for the elastic $\vec e p \to e\vec p$ ~reaction in the four-momentum transfer squared range of 0.5 to 3.5 GeV$^2$. In the single-photon exchange approximation, the ratio $G_{Ep}/G_{Mp}$ is directly proportional to the ratio $P_t/P_{\ell}$. The simultaneous measurement of $P_{t}$ and $P_{\ell}$ in a polarimeter reduces systematic uncertainties. The results for the ratio $G_{Ep}/G_{Mp}$ show a systematic decrease with increasing $Q^2$, indicating for the first time a definite difference in the distribution of charge and magnetization in the proton. The data have been re-analyzed and systematic uncertainties have become significantly smaller than previously published results.
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Journal articles

http://hal.in2p3.fr/in2p3-00024165
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Submitted on : Wednesday, May 25, 2005 - 6:21:17 PM
Last modification on : Thursday, May 9, 2019 - 3:50:02 PM

### Citation

V. Punjabi, C.F. Perdrisat, K.A. Aniol, F.T. Baker, J. Berthot, et al.. Proton elastic form factor ratios to $Q^2$=3.5 GeV$^2$ by polarization transfer. Physical Review C, American Physical Society, 2005, 71, 055202 (27 p.). ⟨10.1103/PhysRevC.71.055202⟩. ⟨in2p3-00024165⟩

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