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BIAGI 1983C

Biagi, S.F. et al.
Observation of a Narrow State at 2.46 GeV/ c² - A Candidate for the Charmed Strange Baryon A⁺
Phys. Lett. 122B (1983) 455;

Reprinted in
Gluons and Heavy Flavours, La Plagne (1983) 341.

Abstracts
A narrow state has been observed in the reaction Σ^– Be → (ΛK^–π⁺π⁺ ) + X in an experiment at the CERN SPS hyperon beam. At 2.46 GeV/c² the effective (ΛK^–π⁺π⁺) mass distribution shows an excess of 82 events above a background estimated to be 147, corresponding to a statistical significance of more than 6 standard deviations. The positive charge of the observed final state, which has strangeness-2, suggests the interpretation as a Cabibbo favored decay of the charmed strange baryon, A⁺ [quark content (csu)]. The cross section times branching ratio is measured to be σ · B = (5.3 ± 2.0) μb/(Be nucleus) for x > 0.6. The invariant production cross section is described by
E d³σ/d p³ propto (1 - x)^{(1.7 ± 0.7)}exp[-(1.1^+0.7_-0.4)p²_T].

Accelerator CERN-SPS Detectors SPEC

Related references
See also
H. J. Burckhart, Ph.D.Thesis, Universitat Heidelberg (1983);
M. Bourquin et al., Nucl. Phys. B153 (1979) 13;

Reactions

	Σ– Be Λ K– 2π+ X	135 GeV (Plab)	mass
	Σ– Be XI/C+! X	135 GeV (Plab)	p, pt, cs
	XI/C+! Λ K– 2π+

Particles studied

XI/C+

ex, qn, mass

Record comments
First evidence for the Ξ_c(2460)⁺.

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