41 ± 8 events of the type X 0 → γγ have been observed in a study of the reaction π − p → n(X 0 → γγ ) at 1.6 GeV/ c incident π -momentum. This provides further evidence to our previous observation of this new X 0 decay mode and allows the determination of the branching ratio Γ(X 0 →γγ) Γ(X 0 → total =(1.7 ± 0.4)%. The theoretical implications of this result are discussed.
THIS MEASUREMENT WHEN COMBINED WITH THE ETAPRIME PRODUCTION CROSS SECTION OF M. BASILE ET AL., NC 3A, 371 (1971) YIELDS A BR(ETAPRIME --> 2GAMMA) OF 1.7 +- 0.4 PCT.
The reactions π−p→ n+(X0→total) and π−p→ n+(X0→neutrals) have been studied at 1.6 GeV/c with the Bologna-CERN neutron missing-mass spectrometer. Both reactions have been detected without the use of visual techniques. The results are: σ(X0→total)=(108±14) μb and σ(X0→neutrals)=(20.0±3.5) μb, giving a branching ratio Γ(X0→neutrals)/Γ(X0→total)=(18.5±2.2)%. The branching ratio for other possible, so far undetected, neutral decay modes of the X0 turns out to be (2.4±1.9)%.
No description provided.
We report on a measurement for the branching-ratio X 0 → 2γ X 0 ar all. Our result is X 0 → 2γ X 0 → all = (2.9 ± 0.9)% .
BY COMPARISON WITH THE KNOWN ETA PRODUCTION CROSS SECTION.
The ratio between the cross sections for the reactions π − p→ χ ↳ 2γ 0 n and π − p → η →2 γ n has been measured to be (2.4 ± 0.9) × 10 −2 , (2.1 ± 0.6) × 10 −2 and (2.8 ± 1.3) × 10 −2 at 3.8,6,8 and 12 GeV/ c incident momentum respectively.
ETAPRIME CROSS SECTIONS DEDUCED FROM THEIR RATIO TO ETA PRODUCTION, USING THE RESULTS OF O. GUISAN ET AL., PL 18, 200 (1965).
None
No description provided.
No description provided.
Measurements were made of the cross section of the reactions π − p → ν ′(958)n, η ′ → 2 γ at momenta at 15, 20, 25, 30 and 40 GeV/c. The experiment was carried out on the IHEP 70 GeV accelerator using the 648 channel hodoscope spectrometer NICE for γ-ray detection. A total of 6000 η′ mesons were recorded. A sharp drop is seen in the differential cross section for t → 0. The dependences of the differential cross sections for the π − p → η ′n and π − p → η n on t are identical. On the basis of the ratio of the cross sections for these reactions at t = 0, i.e. R( η′ n ) t=0 = 0.55 ± 0.06 , the singlet-octet mixing angle for pseudoscalar mesons was determined to be β = −(18.2 ± 1.4)°.
.
AVERAGE RATIO IS 2.76 +- 0.07 PCT.
AVERAGE RATIO IS 0.52 +- 0.02.
None
INCLUDING SYSTEMATIC ERRORS.
STATISTICAL ERRORS ONLY.
STATISTICAL ERRORS ONLY.