Advertisement

Hyperfine Interactions

, 193:39 | Cite as

Observation of πK-atoms with DIRAC-II

  • Y. Allkofer
  • (on behalf of the DIRAC-II collaboration)
Article
  • 31 Downloads

Abstract

We present evidence for the first observation of electromagnetically bound π ± K  ∓ -pairs (πK-atoms) with the DIRAC-II experiment at the CERN-PS. The πK-atoms are produced by the 24 GeV/c proton beam in a thin Pt-target and the dissociated π ± and K  ∓ -mesons analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173±54 πK-atoms. The mean life of πK-atoms is related to the s-wave πK-scattering lengths. From these first data we derive a lower limit for the mean life of 1.5 fs at 84% confidence level.

Keywords

DIRAC experiment Exotic atoms Scattering length Chiral perturbation QCD 

PACS

36.10.-k 32.70.Cs 25.80.Nv 29.30.Aj 

References

  1. 1.
    Weinberg, S.: Phys. Rev. Lett. 17, 616 (1966)CrossRefADSGoogle Scholar
  2. 2.
    Colangelo, G., Gasser, J., Leutwyler, H.: Nucl. Phys. B603, 125 (2001)CrossRefADSGoogle Scholar
  3. 3.
    Adeva, B., et al.: Phys. Lett., B 619, 50 (2005)CrossRefADSGoogle Scholar
  4. 4.
    Descotes-Genon, S., Girlanda, L., Stern, J.: JHEP 0001, 041 (2000); Eur. Phys. J. C27, 115 (2003)CrossRefADSGoogle Scholar
  5. 5.
    Bilen’kii, S.M., van Hieu, N., Nemenov, L.L., Tkebuchava, F.G.: Yad. Fiz. 10, 812 (1969)Google Scholar
  6. 6.
    Bilen’kii, S.M., van Hieu, N., Nemenov, L.L., Tkebuchava, F.G.: Sov. J. Nucl. Phys. 10, 469 (1969)Google Scholar
  7. 7.
    Schweizer, J.: Phys. Lett., B 587, 33 (2004)CrossRefADSGoogle Scholar
  8. 8.
    Nemenov, L.L.: Yad. Fiz. 41, 980 (1985); Sov. J. Nucl. Phys. 41, 629 (1985)Google Scholar
  9. 9.
    Afanasyev, L., et al.: Phys. Lett., B 338, 478 (1994)CrossRefADSGoogle Scholar
  10. 10.
    Adeva, B., et al.: Nucl. Instr. Meth. A 515, 467 (2003)CrossRefADSGoogle Scholar
  11. 11.
    Adeva, B., et al.: Addendum to the DIRAC Proposal. CERN-SPSC-2004-009, SPSC-P-284 Add.4Google Scholar
  12. 12.
    Kuptsov, A.: DIRAC note 08-01. http://dirac.web.cern.ch/DIRAC/i_notes.html
  13. 13.
    Allkofer, Y., et al.: Nucl. Instr. Meth. A 582, 497 (2007)CrossRefADSGoogle Scholar
  14. 14.
    Allkofer, Y., et al.: Nucl. Instr. Meth. A 595, 84 (2008)CrossRefADSGoogle Scholar
  15. 15.
    Allkofer, Y.: Ph.D. thesis, Universität Zürich (2008)Google Scholar
  16. 16.
    Allkofer, Y., Benelli, A., Tauscher, L.: DIRAC note 07-08. http://dirac.web.cern.ch/DIRAC/i_notes.html
  17. 17.
    Adeva, B., et al.: Nucl. Instr. Meth. A 491, 41 (2002)CrossRefADSGoogle Scholar
  18. 18.
    Sakharov, A.D.: Zh. Eksp. Teor. Fiz. 18, 631 (1948)Google Scholar
  19. 19.
    Lednicky, R.; Prep. arXiv:nucl-th/0501065
  20. 20.
    Afanasyev, L., Voskresenskaya, O.: Phys. Lett. B 453, 302 (1999)CrossRefADSGoogle Scholar
  21. 21.
    Allkofer, Y., et al.: Phys. Lett. B 674, 11–16 (2009)ADSGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Y. Allkofer
    • 1
  • (on behalf of the DIRAC-II collaboration)
  1. 1.University of ZurichZürichSwitzerland

Personalised recommendations