Advertisement

The European Physical Journal A

, Volume 32, Issue 1, pp 69–75 | Cite as

Beam-helicity asymmetry in photon and pion electroproduction in the Δ(1232)-resonance region at Q2 = 0.35(GeV/c)2

  • I. K. Bensafa
  • P. Achenbach
  • M. Ases Antelo
  • C. Ayerbe
  • D. Baumann
  • R. Böhm
  • D. Bosnar
  • E. Burtin
  • X. Defaÿ
  • N. D'Hose
  • M. Ding
  • M. O. Distler
  • L. Doria
  • H. FonvieilleEmail author
  • J. M. Friedrich
  • J. Friedrich
  • J. García Llongo
  • P. Janssens
  • G. Jover Mañas
  • M. Kohl
  • G. Laveissière
  • M. Lloyd
  • M. Makek
  • J. Marroncle
  • H. Merkel
  • P. Merle
  • U. Müller
  • L. Nungesser
  • B. Pasquini
  • R. Pérez Benito
  • J. Pochodzalla
  • M. Potokar
  • G. Rosner
  • S. Sánchez Majos
  • M. Seimetz
  • S. Širca
  • T. Spitzenberg
  • G. Tamas
  • R. Van de Vyver
  • L. Van Hoorebeke
  • Th. Walcher
  • M. Weis
Regular Article - Hadron Physics

Abstract.

The beam-helicity asymmetry has been measured simultaneously for the reactions \( \;\stackrel{{\rightarrow}}{{e}}\;\) pepγ and \( \;\stackrel{{\rightarrow}}{{e}}\;\) pepπ 0 in the Δ(1232)-resonance region at Q 2 = 0.35(GeV/c)2. The experiment was performed at MAMI with a longitudinally polarized beam and an out-of-plane detection of the proton. The results are compared with calculations based on dispersion relations for virtual Compton scattering and with the MAID model for pion electroproduction. There is an overall good agreement between experiment and theoretical calculations. The remaining discrepancies may be ascribed to an imperfect parametrization of some γ (*) NπN multipoles, mainly contributing to the non-resonant background. The beam-helicity asymmetry in both channels (γ and π 0) shows a good sensitivity to these multipoles and should allow future improvement in their parametrization.

PACS.

13.40.-f Electromagnetic processes and properties 13.60.Fz Elastic and Compton scattering 13.60.Le Meson production 14.20.Gk Baryon resonances with S = 0 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    X. Ji, Phys. Lett. B 638, 178 (2006) hep-ph/0604128.CrossRefADSGoogle Scholar
  2. 2.
    M. Diehl, Phys. Rep. 388, 41 (2003) hep-ph/0307382.CrossRefADSGoogle Scholar
  3. 3.
    P. Bartsch, Phys. Rev. Lett. 88, 142001 (2002) nucl-ex/0112009.CrossRefADSGoogle Scholar
  4. 4.
    D. Elsner, Eur. Phys. J. A 27, 91 (2006) nucl-ex/0507014.CrossRefADSGoogle Scholar
  5. 5.
    P.A.M. Guichon, G.Q. Liu, A.W. Thomas, Nucl. Phys. A 591, 606 (1995) nucl-th/9605031.CrossRefADSGoogle Scholar
  6. 6.
    J. Roche, Phys. Rev. Lett. 85, 708 (2000).CrossRefADSGoogle Scholar
  7. 7.
    Jefferson Lab Hall A (G. Laveissiere), Phys. Rev. Lett. 93, 122001 (2004) hep-ph/0404243.CrossRefADSGoogle Scholar
  8. 8.
    P. Bourgeois, Phys. Rev. Lett. 97, 212001 (2006) nucl-ex/0605009.CrossRefADSGoogle Scholar
  9. 9.
    P. Kroll, M. Schurmann, P.A.M. Guichon, Nucl. Phys. A 598, 435 (1996) hep-ph/9507298.CrossRefADSGoogle Scholar
  10. 10.
    CLAS Collaboration (K. Joo), Phys. Rev. C 68, 032201 (2003) nucl-ex/0301012.CrossRefADSGoogle Scholar
  11. 11.
    D. Drechsel, L. Tiator, J. Phys. G 18, 449 (1992).CrossRefADSGoogle Scholar
  12. 12.
    K.I. Blomqvist, Nucl. Instrum. Methods A 403, 263 (1998).CrossRefADSGoogle Scholar
  13. 13.
    I.K. Bensafa, PhD Thesis, UBP Clermont-Ferrand, 2006, DU 1647.Google Scholar
  14. 14.
    H. Fonvieille, I.K. Bensafa, LPC internal reports PCCF-RI-0604 and PCCF-RI-0605 (2006).Google Scholar
  15. 15.
    B. Pasquini, Eur. Phys. J. A 11, 185 (2001) hep-ph/0102335.CrossRefADSGoogle Scholar
  16. 16.
    D. Drechsel, Nucl. Phys. A 645, 145 (1999) nucl-th/9807001, http://www.kph.uni-mainz.de/MAID/. CrossRefADSGoogle Scholar
  17. 17.
    M. Vanderhaeghen, Phys. Rev. C 62, 025501 (2000) hep-ph/0001100.CrossRefADSGoogle Scholar
  18. 18.
    A.V. Afanasev, M.I. Konchatnij, N.P. Merenkov, J. Exp. Theor. Phys. 102, 220 (2006) hep-ph/0507059.CrossRefGoogle Scholar
  19. 19.
    H. Fonvieille, LPC internal report PCCF-RI-0607 (2006).Google Scholar
  20. 20.
    G.I. Smirnov, hep-ph/0504045 (2005).Google Scholar
  21. 21.
    D. Drechsel, B. Pasquini, M. Vanderhaeghen, Phys. Rep. 378, 99 (2003) hep-ph/0212124.CrossRefADSGoogle Scholar
  22. 22.
    S.S. Kamalov, S.N. Yang, Phys. Rev. Lett. 83, 4494 (1999) nucl-th/9904072, http://www.kph.uni-mainz.de/ MAID/dmt/.CrossRefADSGoogle Scholar
  23. 23.
    L. Tiator, private communication.Google Scholar

Copyright information

© Società Italiana di Fisica and Springer-Verlag 2007

Authors and Affiliations

  • I. K. Bensafa
    • 1
  • P. Achenbach
    • 2
  • M. Ases Antelo
    • 2
  • C. Ayerbe
    • 2
  • D. Baumann
    • 2
  • R. Böhm
    • 2
  • D. Bosnar
    • 5
  • E. Burtin
    • 3
  • X. Defaÿ
    • 1
  • N. D'Hose
    • 3
  • M. Ding
    • 2
  • M. O. Distler
    • 2
  • L. Doria
    • 2
  • H. Fonvieille
    • 1
    Email author
  • J. M. Friedrich
    • 8
  • J. Friedrich
    • 2
  • J. García Llongo
    • 2
  • P. Janssens
    • 4
  • G. Jover Mañas
    • 2
  • M. Kohl
    • 2
  • G. Laveissière
    • 1
  • M. Lloyd
    • 2
  • M. Makek
    • 5
  • J. Marroncle
    • 3
  • H. Merkel
    • 2
  • P. Merle
    • 2
  • U. Müller
    • 2
  • L. Nungesser
    • 2
  • B. Pasquini
    • 7
  • R. Pérez Benito
    • 2
  • J. Pochodzalla
    • 2
  • M. Potokar
    • 6
  • G. Rosner
    • 9
  • S. Sánchez Majos
    • 2
  • M. Seimetz
    • 2
    • 3
  • S. Širca
    • 6
  • T. Spitzenberg
    • 2
  • G. Tamas
    • 2
  • R. Van de Vyver
    • 4
  • L. Van Hoorebeke
    • 4
  • Th. Walcher
    • 2
  • M. Weis
    • 2
  1. 1.Laboratoire de Physique Corpusculaire IN2P3-CNRSUniversité Blaise PascalAubière CedexFrance
  2. 2.Institut für KernphysikJohannes Gutenberg-UniversitätMainzGermany
  3. 3.C.E. SaclayCEA Dapnia-SPhNGif-sur-Yvette CedexFrance
  4. 4.Department of Subatomic and Radiation PhysicsUniversity of GentGentBelgium
  5. 5.Department of PhysicsUniversity of ZagrebZagrebCroatia
  6. 6.Institut Jožef StefanUniversity of LjubljanaLjubljanaSlovenia
  7. 7.Dipartimento di Fisica Nucleare e TeoricaUniversità degli Studi di Pavia, and INFN, Sezione di PaviaPaviaItaly
  8. 8.Physik DepartmentTechnische Universität MünchenGarchingGermany
  9. 9.Department of Physics and AstronomyUniversity of GlasgowGlasgowUK

Personalised recommendations