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RESEARCH PRODUCT

Test of Low-Energy Theorems forH1(γ→,π0)H1in the Threshold Region

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The photon asymmetry in the reaction H-1(, pi (0))H-1 close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the S-wave and all three P-wave amplitudes. The values obtained at threshold are E0+ = [-1.33 +/- 0.08(stat) +/- 0.03(syst)] x 10(-3)/m(pi+), P-1 = [9.47 +/- 0.08(stat) +/- 0.29(syst)] x 10(-3)q /m(pi+)(2) P-2 [-9.46 +/- 0.1(stat) +/- 0.29(syst)] x 10(-3)q/m(pi+)(2), and P-3 = [11.48 +/- 0.06(stat) +/- 0.35(syst)] x 10(-3)q/m(pi+)(2).