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Search for Pentaquarks in the Hadronic Decays of the Z Boson with the DELPHI Detector at LEP.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

<mark>Journal publication date</mark>20/09/2007
<mark>Journal</mark>Physics Letters B
Issue number2-4
Number of pages10
Pages (from-to)151-160
Publication StatusPublished
<mark>Original language</mark>English


The quark model does not exclude states composed of more than three quarks, like pentaquark systems. Controversial evidence for such states has been published in the last years, in particular: for a strange pentaquark Θ(1540)+; for a double-strange state, the Ξ(1862)−−, subsequently called Φ(1860)−−; and for a charmed state, the Θc(3100)0. If confirmed, a full pentaquark family might exist; such pentaquark states could be produced in e+e− annihilations near the Z energy. In this Letter a search for pentaquarks is described using the DELPHI detector at LEP, characterized by powerful particle identification sub-systems crucial in the separation of the signal from the background for these states. At 95% CL, upper limits are set on the production rates N of such particles and their charge-conjugate state per Z decay: , NΘ++<1.6×10−3, NΦ(1860)−−×Br(Φ(1860)−−→Ξ−π−)<2.9×10−4, .