Measurement of GEp/GMp via polarization transfer at Q2 = 0.4 GeV /c2

The polarization transfer from longitudinally polarized electrons to protons in the elastic scattering p(\(\)e, e'\(\)p) has been measured around Q2 = 0.4 (GeV/c)2 with the three-spectrometer facility at the Mainz microtron MAMI. From this polarization transfer the ratio GEp/(GMp/μp) has been determined. The ratio is found to be slightly less than unity in agreement with recent results from other laboratories and from the Rosenbluth separation of cross-sections measured with unpolarized electrons.