A first measurement of the ΛΛ̄ and ΛΛ (Λ̄Λ̄) spin compositions in hadronic Z0 decays

The OPAL Collaboration

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32 Scopus citations


The spin composition of ΛΛ̄, ΛΛ and Λ̄Λ̄ pairs at low invariant mass values has been measured for the first time in multihadronic Z0 decays with the OPAL detector at LEP. No single spin state has been observed in the ΛΛ̄ sample, verifying that the low mass enhancement in this sample, attributed to local baryon number compensation, is not a resonance state. The fraction of the spin 1 contribution to the ΛΛ̄ pairs was found to be consistent with the value 0.75, as expected from a statistical spin mixture. This may be the net effect of many different QCD processes which contribute to the hyperon anti-hyperon pair production. The spin composition of the identical ΛΛ and Λ̄Λ̄ pairs, well above threshold, is found to be similar to that of the ΛΛ̄ sample. A ΛΛ emitter dimension is estimated from the data assuming the onset of the Pauli exclusion principle near threshold.

Original languageEnglish
Pages (from-to)377-387
Number of pages11
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1-4
StatePublished - 19 Sep 1996
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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