First measurement of the helicity dependence for the γp → pπreaction

  • GDH and A2 Collaborations
  • 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. Jennewein
  • F. 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
Regular Article - Experimental Physics

Abstract.

The helicity dependence of the total cross-section and the invariant-mass distributions in the (pπ±) and (π+π-) final states for the γppπ+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.

PACS.

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

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Copyright information

© Società Italiana di Fisica and Springer-Verlag 2007

Authors and Affiliations

  • GDH and A2 Collaborations
  • J. Ahrens
    • 8
  • S. Altieri
    • 12
    • 13
  • J. R. M. Annand
    • 6
  • H. -J. Arends
    • 8
  • R. Beck
    • 8
  • M. A. Blackston
    • 3
  • C. Bradtke
    • 2
  • A. Braghieri
    • 12
  • N. d'Hose
    • 5
  • H. Dutz
    • 2
  • A. Fix
    • 14
  • S. Goertz
    • 1
  • P. Grabmayr
    • 15
  • S. Hasegawa
    • 10
  • E. Heid
    • 8
  • H. Holvoet
    • 4
  • N. Horikawa
    • 11
  • T. Iwata
    • 10
  • O. Jahn
    • 8
  • P. Jennewein
    • 8
  • F. Klein
    • 2
  • R. Kondratiev
    • 9
  • M. Lang
    • 8
  • B. Lannoy
    • 4
  • V. Lisin
    • 9
  • M. Martinez-Fabregate
    • 8
  • J. C. McGeorge
    • 6
  • W. Meyer
    • 1
  • A. Panzeri
    • 12
    • 13
  • P. Pedroni
    • 12
  • T. Pinelli
    • 12
    • 13
  • I. Preobrajenski
    • 8
    • 9
  • G. Reicherz
    • 1
  • Ch. Rohlof
    • 2
  • G. Rosner
    • 6
  • M. Rost
    • 8
  • T. Rostomyan
    • 4
    • 12
  • D. Ryckbosch
    • 4
  • M. Schumacher
    • 7
  • B. Seitz
    • 7
  • G. Tamas
    • 8
  • A. Thomas
    • 8
  • R. Van de Vyver
    • 4
  • H. R. Weller
    • 3
  • F. Zapadtka
    • 7
  1. 1.Insitut für ExperimentalphysikRuhr-Universität BochumBochumGermany
  2. 2.Physikalisches InstitutUniversität BonnBonnGermany
  3. 3.Department of PhysicsDuke UniversityDurhamUSA
  4. 4.Subatomaire en StralingsfysicaUniversiteit GentGentBelgium
  5. 5.CEA Saclay, DSM/DAPNIA/SPhNGif-sur-Yvette CedexFrance
  6. 6.Department of Physics and AstronomyUniversity of GlasgowGlasgowUK
  7. 7.II.Physikalisches InstitutUniversität GöttingenGöttingenGermany
  8. 8.Institut für KernphysikUniversität MainzMainzGermany
  9. 9.INRAcademy of ScienceMoscowRussia
  10. 10.Department of PhysicsNagoya UniversityChikusa-ku, NagoyaJapan
  11. 11.CIRSENagoya UniversityChikusa-ku, NagoyaJapan
  12. 12.Sezione di PaviaINFNPaviaItaly
  13. 13.Dipartimento di Fisica Nucleare e TeoricaUniversità di PaviaPaviaItaly
  14. 14.Laboratory of Mathematical PhysicsTomsk Polytechnic UniversityTomskRussia
  15. 15.Physikalisches InstitutUniversität TübingenTübingenGermany

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