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Limits for the central production of Theta(+) and Xi(--) pentaquarks in 920-GeV pA collisions

Authors: ATLAS Collaboration, J. Carvalho

Ref.: Physical Review Letters 93, 212003 (2004)

Abstract: We have searched for Θ+(1540) and Ξ−−(1862) pentaquark candidates in proton-induced reactions on C, Ti, and W targets at midrapidity and s√=41.6  GeV. In 2×108 inelastic events we find no evidence for narrow (σ≈5  MeV) signals in the Θ+→pK0S and Ξ−−→Ξ−π− channels; our 95% C.L. upper limits (UL) for the inclusive production cross section times branching fraction B dσ/dy|y≈0 are (4–16)μb/N for a Θ+ mass between 1521 and 1555 MeV, and 2.5μb/N for the Ξ−−. The UL of the yield ratio of Θ+/Λ(1520)<(3–12)% is significantly lower than model predictions. Our UL of B Ξ−−/Ξ(1530)0<4% is at variance with the results that have provided the first evidence for the Ξ−−.

DOI: 10.1103/PhysRevLett.93.212003

URL: arxiv.org