First measurement of the helicity dependence for the γp → pπreaction

J. Ahrens, S. Altieri, J. R.M. Annand, H. J. Arends, R. Beck, M. A. Blackston, C. Bradtke, A. Braghieri, N. D'Hose, H. Dutz, A. Fix, S. Goertz, P. Grabmayr, S. Hasegawa, E. Heid, H. Holvoet, N. Horikawa, T. Iwata, O. Jahn, P. JenneweinF. Klein, R. Kondratiev, M. Lang, B. Lannoy, V. Lisin, M. Martinez-Fabregate, J. C. McGeorge, W. Meyer, A. Panzeri, P. Pedroni, T. Pinelli, I. Preobrajenski, G. Reicherz, Ch Rohlof, G. Rosner, M. Rost, T. Rostomyan, D. Ryckbosch, M. Schumacher, B. Seitz, G. Tamas, A. Thomas, R. Van De Vyver, H. R. Weller, F. Zapadtka

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29 Citations (Scopus)


The helicity dependence of the total cross-section and the invariant-mass distributions in the (pπ±) and (π+π -) final states for the γp → pπ+π - reaction have been measured for the first time at incident photon energies from 400 to 800MeV. The measurement was performed with the large-acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. Although this channel is found to be predominantly excited by the intermediate production of a Δπ state, both the measured unpolarized and the helicity-dependent observables are generally not well described by the existing theoretical models.

Original languageEnglish
Article number11
Pages (from-to)11-21
Number of pages11
JournalEuropean Physical Journal A
Issue number1
Publication statusPublished - Oct 2007
Externally publishedYes


  • 13.60.Le Meson production
  • 14.20.Gk Baryon resonances with S = 0
  • 25.20.Lj Photoproduction reactions

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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