Entanglement in joint \(\Lambda \bar{\Lambda}\) decay

Regular Article - Theoretical Physics


We investigate the joint \( \Lambda \bar{\Lambda}\) decay in the reaction \( e^{+} e^{-} \rightarrow \gamma \Lambda(\rightarrow p\pi^{-}) \bar{\Lambda}(\rightarrow \bar{p}\pi^{+})\). This reaction may provide information on the electromagnetic form factors of the Lambda baryon, in the time-like region. We present a conventional diagram-based calculation where production and decay steps are coherent and summations over final-state proton and anti-proton spins are performed. The resulting cross-section distribution is explicitly covariant as it is expressed in scalar products of the four-momentum vectors of the participating particles. We compare this calculation with that of the folding method which we extend and make explicitly covariant. In the folding method production and decay distributions, not amplitudes, are folded together. Of particular importance is then a correct counting of the number of possible intermediate-hyperon-spin states.


  1. 1.
    BABAR Collaboration (B. Aubert et al.), Phys. Rev. D 76, 092006 (2007)CrossRefGoogle Scholar
  2. 2.
    L.V. Kardapoltzev, Bachelor's thesis, Novosibirsk State University, 2007, unpublishedGoogle Scholar
  3. 3.
    H. Czyz, A. Grzelińska, J.H. Kühn, Phys. Rev. D 75, 074026 (2007)ADSCrossRefGoogle Scholar
  4. 4.
    O.D. Dalkarov, P.A. Khakhulin, A.Yu. Voronin, Nucl. Phys. A 833, 104 (2010)ADSCrossRefGoogle Scholar
  5. 5.
    H. Pilkuhn, Relativistic Particle Physics (Springer-Verlag, Berlin, 1979)Google Scholar
  6. 6.
    F. Anulli, Nucl. Phys. B (Proc. Suppl.) 225-227, 205 (2012)ADSCrossRefGoogle Scholar
  7. 7.
    S. Dobbs, A. Tomaradze, T. Xiao, Kamal K. Seth, G. Bonvicini, Phys. Lett. B 739, 90 (2014)ADSCrossRefGoogle Scholar
  8. 8.
    DM2 Collaboration (D. Bisello et al.), Z. Phys. C 48, 23 (1990)CrossRefGoogle Scholar
  9. 9.
    J.G. Körner, M. Kuroda, Phys. Rev. D 16, 2165 (1977)ADSCrossRefGoogle Scholar
  10. 10.
    A.Z. Dubničková, S. Dubnička, M.E. Biagini, A. Castro, Czech. J. Phys. 41, 1177 (1991)ADSCrossRefGoogle Scholar
  11. 11.
    V.L. Chernyak, A.R. Zhitnitskii, V.G. Serbo, JETP Lett. 26, 594 (1977)ADSGoogle Scholar

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© SIF, Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Department of physics and astronomyUppsala UniversityUppsalaSweden

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