A measurement of the π0, η and η′ electromagnetic form factors

Behrend, H. -J.; Criegee, L.; Field, J. H.; Franke, G.; Jung, H.; Meyer, J.; Podobrin, O.; Schr�der, V.; Winter, G. G.; Bussey, P. J.; Campbell, A. J.; Hendry, D.; Lumsdon, S. J.; Skillicorn, I. O.; Ahme, J.; Blobel, V.; Feindt, M.; Fenner, H.; Harjes, J.; K�hne, J. H.; Peters, J. H.; Spitzer, H.; Weihrich, T.; Apel, W. -D.; Engler, J.; Fl�gge, G.; Fries, D. C.; Fuster, J.; Gamerdinger, K.; Grosse-Wiesmann, P.; K�ster, H.; M�ller, H.; Ranitzsch, K. H.; Schneider, H.; Boer, W.; Buschhorn, G.; Grindhammer, G.; Gunderson, B.; Kiesling, C.; Kotthaus, R.; Kroha, H.; L�ers, D.; Oberlack, H.; Schacht, P.; Scholz, S.; Wiedenmann, W.; Davier, M.; Grivaz, J. F.; Haissinski, J.; Journ�, V.; Diberder, F.; Veillet, J. -J.; Blohm, K.; George, R.; Goldberg, M.; Hamon, O.; Kapusta, F.; Poggioli, L.; Rivoal, Solene Pierre Marie; D'Agostinis, Giovanni; Ferrarotto, F.; Iacovacci, M.; Shooshtari, G.; Stella, B.; Cozzika, G.; Ducros, Y.; Alexander, G.; Beck, A.; Bella, G.; Grunhaus, J.; Klatchko, A.; Levy, A.; Milst�ne, C.

doi:10.1007/BF01549692

We present measurement of the π0γ*γ, ηγ*γ and η′γ*γ form factors. The π0-form factor is for the first time observed in the space-like region. The transition form factor of the η-meson is determined from its decay modes π+π-π0, π+π-γ and the neutral decay mode γγ. The decay of the η′ is observed in the decay channels ργ, ηπ+π- with η→γγ and in the four charged prong final state stemming from ηπ+π- with the η decaying into π+π-(π0/γ). All form factors agree well with a simple ρ-pole predicted by the vector meson dominance model and also with the QCD inspired Brodsky-Lepage model. © 1991 Springer-Verlag.

A measurement of the π0, η and η′ electromagnetic form factors / Behrend, H.-J., Criegee, L., Field, J.H., Franke, G., Jung, H., Meyer, J., Podobrin, O., Schr�der, V., Winter, G.G., Bussey, P.J., Campbell, A.J., Hendry, D., Lumsdon, S.J., Skillicorn, I.O., Ahme, J., Blobel, V., Feindt, M., Fenner, H., Harjes, J., K�hne, J.H., et al.. - In: ZEITSCHRIFT FÜR PHYSIK. C, PARTICLES AND FIELDS. - ISSN 0170-9739. - 49:3(1991), pp. 401-409. [10.1007/BF01549692]