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Test of low-energy theorems for p(\vec{gamma},π^{0})p in the threshold region

A. Schmidt·P. Achenbach·J. Ahrens·H. J. Arends·R. Beck·A. M. Bernstein·V. Hejny·M. Kotulla·B. Krusche·V. Kuhr·R. Leukel·I. J. D. MacGregor·J. C. McGeorge·V. Metag·V. M. Olmos de Leon·F. Rambo·U. Siodlaczek·H. Stroeher·Th. Walcher·J. Weiss·F. Wissmann·M. Wolf
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Abstract

The photon asymmetry in the reaction p(\vecγ,π^{0})p 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 low-energy theorems based on the parameter-free third-order calculations of heavy-baryon chiral perturbation theory for P1 and P2 agree with the experimental values.

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A. Schmidt, P. Achenbach, J. Ahrens, H. J. Arends, R. Beck, A. M. Bernstein, V. Hejny, M. Kotulla, B. Krusche, V. Kuhr, R. Leukel, I. J. D. MacGregor, J. C. McGeorge, V. Metag, V. M. Olmos de Leon, F. Rambo, U. Siodlaczek, H. Stroeher, Th. Walcher, J. Weiss, F. Wissmann, M. Wolf. 2001-05-17. Test of low-energy theorems for p(\vec{gamma},π^{0})p in the threshold region. https://doi.org/10.1103/physrevlett.87.232501

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