Photoproduction of π0π0 - and π0π+ -pairs off the proton from threshold to the second resonance region

  • F. Zehr
  • B. Krusche
  • P. Aguar
  • J. Ahrens
  • J. R. M. Annand
  • H. J. Arends
  • R. Beck
  • V. Bekrenev
  • B. Boillat
  • A. Braghieri
  • D. Branford
  • W. J. Briscoe
  • J. Brudvik
  • S. Cherepnya
  • R. F. B. Codling
  • E. J. Downie
  • P. Drexler
  • D. I. Glazier
  • L. V. Fil’kov
  • A. Fix
  • R. Gregor
  • E. Heid
  • D. Hornidge
  • I. Jaegle
  • O. Jahn
  • V. L. Kashevarov
  • A. Knezevic
  • R. Kondratiev
  • M. Korolija
  • M. Kotulla
  • D. Krambrich
  • A. Kulbardis
  • M. Lang
  • V. Lisin
  • K. Livingston
  • S. Lugert
  • I. J. D. MacGregor
  • D. M. Manley
  • Y. Maghrbi
  • M. Martinez
  • J. C. McGeorge
  • D. Mekterovic
  • V. Metag
  • B. M. K. Nefkens
  • A. Nikolaev
  • M. Ostrick
  • P. Pedroni
  • F. Pheron
  • A. Polonski
  • S. Prakhov
  • J. W. Price
  • G. Rosner
  • M. Rost
  • T. Rostomyan
  • S. Schumann
  • D. Sober
  • A. Starostin
  • I. Supek
  • C. M. Tarbert
  • A. Thomas
  • M. Unverzagt
  • Th. Walcher
  • D. P. Watts
Regular Article - Experimental Physics

Abstract

Precise total cross-sections and invariant-mass distributions have been measured for photoproduction of pion pairs off the proton producing \(\ensuremath p\pi^0\pi^0\) and \(\ensuremath n\pi^+\pi^0\) final states from the threshold region up to 800MeV incident photon energy. Additionally, beam helicity asymmetries have been measured in the second resonance region (550MeV-820MeV). The experiment was performed at the tagged photon beam of the Mainz MAMI accelerator with the Crystal Ball and TAPS detectors combined to give an almost 4\( \pi\) solid-angle electromagnetic calorimeter. The results are much more precise than any previous measurements and confirm the chiral perturbation theory predictions for the threshold behavior of these reactions. In the second resonance region, the invariant-mass distributions of meson-meson and meson-nucleon pairs are in reasonable agreement with model predictions, but none of the models reproduce the asymmetries for the mixed-charge channel.

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Copyright information

© SIF, Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • F. Zehr
    • 1
  • B. Krusche
    • 1
  • P. Aguar
    • 2
  • J. Ahrens
    • 2
  • J. R. M. Annand
    • 3
  • H. J. Arends
    • 2
  • R. Beck
    • 2
    • 4
  • V. Bekrenev
    • 5
  • B. Boillat
    • 1
  • A. Braghieri
    • 6
  • D. Branford
    • 7
  • W. J. Briscoe
    • 8
  • J. Brudvik
    • 9
  • S. Cherepnya
    • 10
  • R. F. B. Codling
    • 3
  • E. J. Downie
    • 3
  • P. Drexler
    • 12
  • D. I. Glazier
    • 7
  • L. V. Fil’kov
    • 10
  • A. Fix
    • 11
  • R. Gregor
    • 12
  • E. Heid
    • 2
  • D. Hornidge
    • 13
  • I. Jaegle
    • 1
  • O. Jahn
    • 2
  • V. L. Kashevarov
    • 10
    • 2
  • A. Knezevic
    • 14
  • R. Kondratiev
    • 15
  • M. Korolija
    • 14
  • M. Kotulla
    • 1
  • D. Krambrich
    • 2
  • A. Kulbardis
    • 5
  • M. Lang
    • 2
    • 4
  • V. Lisin
    • 15
  • K. Livingston
    • 3
  • S. Lugert
    • 12
  • I. J. D. MacGregor
    • 3
  • D. M. Manley
    • 16
  • Y. Maghrbi
    • 1
  • M. Martinez
    • 2
  • J. C. McGeorge
    • 3
  • D. Mekterovic
    • 14
  • V. Metag
    • 12
  • B. M. K. Nefkens
    • 9
  • A. Nikolaev
    • 2
    • 4
  • M. Ostrick
    • 2
  • P. Pedroni
    • 6
  • F. Pheron
    • 1
  • A. Polonski
    • 15
  • S. Prakhov
    • 9
  • J. W. Price
    • 9
  • G. Rosner
    • 3
  • M. Rost
    • 2
  • T. Rostomyan
    • 6
  • S. Schumann
    • 2
    • 4
  • D. Sober
    • 17
  • A. Starostin
    • 9
  • I. Supek
    • 14
  • C. M. Tarbert
    • 7
  • A. Thomas
    • 2
  • M. Unverzagt
    • 2
    • 4
  • Th. Walcher
    • 2
  • D. P. Watts
    • 7
  1. 1.Department of PhysicsUniversity of BaselBaselSwitzerland
  2. 2.Institut für KernphysikUniversity of MainzMainzGermany
  3. 3.SUPA, School of Physics and AstronomyUniversity of GlasgowGlasgowUK
  4. 4.Helmholtz-Institut für Strahlen- und KernphysikUniversity BonnBonnGermany
  5. 5.Petersburg Nuclear Physics InstituteGatchinaRussia
  6. 6.INFNSezione di PaviaPaviaItaly
  7. 7.School of PhysicsUniversity of EdinburghEdinburghUK
  8. 8.Center for Nuclear StudiesThe George Washington UniversityWashingtonUSA
  9. 9.University of California Los AngelesLos AngelesUSA
  10. 10.Lebedev Physical InstituteMoscowRussia
  11. 11.Laboratory of Mathematical PhysicsTomsk Polytechnic UniversityTomskRussia
  12. 12.II. Physikalisches InstitutUniversity of GiessenGiessenGermany
  13. 13.Mount Allison UniversityNew BrunswickCanada
  14. 14.Rudjer Boskovic InstituteZagrebCroatia
  15. 15.Institute for Nuclear ResearchMoscowRussia
  16. 16.Kent State UniversityKentUSA
  17. 17.The Catholic University of AmericaWashingtonUSA

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