We find an increase in ∑ ± production between E cm = 4 and 7 GeV which is consistent with charmed baryon production models. A search for the decay ∧ c − → ∑ ± π ± π − yields no significant peaks.
43 +- 16 ANTI-SIGMAS DETECTED ALTOGETHER.
The production of antineutrons and charged Σ's in e+e− annihilations has been measured at s=4 and 7 GeV and at the ψ(3.1) resonance. Two packages containing spark chambers, steel plates, and scintillation counters were added to each side of the Mark I detector at SPEAR. Antineutrons were identified by annihilations which produced large-angle charged prongs characteristic of a high-Q reaction. The resulting antineutron cross sections and momentum distributions are consistent with previous antiproton results. Charged Σ's were detected by forming mass combinations with the n's and charged tracks in the Mark I. A clear signal is seen in the 7-GeV and ψ data, with little or no signal at s=4 GeV. The increase in Σ± production between 4 and 7 GeV is consistent with simple expectations for charmed-baryon production. A search for the decays Λc−→Σ±π∓π− and Σc*Σc→Λc−π± yields no significant peaks. An upper limit, at the 90% confidence level, of σΛcB(Λc→Σ±π∓π−)<56 pb is set.
No description provided.
THE ANTI-SIGMA PRODUCTION CROSS SECTIONS WERE REPORTED IN T. FERGUSON ET AL., PL 79B, 161 (1978).
NOTE THAT TWICE THE ANTI-NEUTRON CROSS SECTIONS ARE PLOTTED IN THE FIGURES. NUMERICAL VALUES OF DATA ON FIGURES SUPPLIED BY T. FERGUSON.
Forum