Journal article

Publication year: 2005

Pages: 113-127

Journal: The European Physical Journal A

Volume number: 23

Issue number: 1

ISSN: 1434-6001

eISSN: 1434-601X

DOI Link: https://doi.org/10.1140/epja/i2004-10056-2

Publisher: Springer

Abstract: 
An experiment on the radiative pi(+)-meson photoproduction from the proton (gammap --> gammapi(+)n) was carried out at the Mainz Microtron MAMI in the kinematic region 537 MeV < E-gamma < 817 MeV, 140degrees less than or equal to theta(gammagamma')(cm) less than or equal to 180degrees. The pi(+)-meson polarizabilities have been determined from a comparison of the data with the predictions of two different theoretical models, the first one being based on an effective pole model with pseudoscalar coupling while the second one is based on diagrams describing both resonant and nonresonant contributions. The validity of the models has been verified by comparing the predictions with the present experimental data in the kinematic region where the pion polarizability contribution is negligible (s(1) < 5m(pi)(2)) and where the difference between the predictions of the two models does not exceed 3%. In the region, where the pion polarizability contribution is substantial (5 < s(1)/m(pi)(2) < 15, -12 < t/m(pi)(2) < -2), the difference (alpha - beta)(pi+) of the electric (alpha) and the magnetic (beta) polarizabilities has been determined. As a result we find (alpha - beta)(pi+) = (11.6 +/- 1.5(stat) +/- 3.0(syst) +/- 0.5(mod)) x 10(-4) fm(3). This result is at variance with recent calculations in the framework of chiral perturbation theory.

Harvard Citation style: Ahrens, J., Alexeev, V., Annand, J., Arends, H., Beck, R., Caselotti, G., et al. (2005) Measurement of the π⁺-meson polarizabilities via the γP→γπ⁺n reaction, The European Physical Journal A, 23(1), pp. 113-127. https://doi.org/10.1140/epja/i2004-10056-2

APA Citation style: Ahrens, J., Alexeev, V., Annand, J., Arends, H., Beck, R., Caselotti, G., Cherepnya, S., Drechsel, D., Fil'kov, L., Föhl, K., Giller, I., Gralmayr, P., Hehl, T., Hornidge, D., Kashevarov, V., Kotulla, N., Krambrich, D., Krusche, B., Lang, M., ...Walcher, T. (2005). Measurement of the π⁺-meson polarizabilities via the γP→γπ⁺n reaction. The European Physical Journal A. 23(1), 113-127. https://doi.org/10.1140/epja/i2004-10056-2