Search for pentaquark states in Z decays

Exotic hadrons made of five quarks (pentaquarks) are searched for in hadronic Z decays collected by the ALEPH detector at LEP. No significant signal is observed. At 95% C.L., upper limits are set on the production rates N of such particles and their charge-conjugate state per Z decay: NΘ(1535)+⋅BR(Θ(1535)+→pKS0)<6.2×10−4, NΞ(1862)−−⋅BR(Ξ(1862)−−→Ξ−π−)<4.5×10−4, NΞ(1862)0⋅BR(Ξ(1862)0→Ξ−π+)<8.9×10−4, NΘc(3100)0⋅BR(Θc(3100)0→D*−p)<6.3×10−4, NΘc(3100)0⋅BR(Θc(3100)0→D−p)<31×10−4.

electron positron: colliding beams
electron positron: annihilation
Z0: electroproduction
Z0: hadronic decay
pentaquark: search for
Theta(1540)
postulated particle: Xi(1860)
postulated particle: Theta/c(3100)
mass spectrum: (p K)
mass spectrum: (Lambda pi)

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Figures(0)

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