The results of the first experiment performed at DCI in e + e − annihilations in the c.m. energy range 1.350–2.125 GeV region are presented. The cross sections of various multipion channels are extracted. Significant structure appears in some specific channels. A relatively narrow resonance around 1.660 GeV decaying into 3 π 's is found. Charged and neutral multiplicities, and also the ratio R are given.
PEAK CROSS SECTION FROM FIT WITH BREIT-WIGNER RESONANCE PLUS CONSTANT BACKGROUND TO ISOSCALAR JPC = 1-- STRUCTURE OF MASS 1652 +- 17 MEV AND WIDTH OF 42 +- 17 MEV.
R VALUE SEEMS CONSTANT OVER THIS ENERGY RANGE.
None
SINGLE CHARGED PARTICLE MOMENTUM DISTRIBUTION.
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The cross section e + e − → π + π − π o has been measured in the φ energy region and at three other energies (915, 990, 1076 MeV) chosen outside the ω and φ resonances. In the same experiment the energy position and the width of the φ resonance have been determined from the φ →K S o K L o channel. It is found that the magnitude and energy dependence of the experimental cross section are well described by coherent production of ω and φ in the whole energy range 770 to 1076 MeV. Our data clearly show an interference effect which corresponds to an opposite sign between the two products g γω g ω →3 π and g γφ g φ →3 π of the coupling constants.
EXPERIMENTAL CROSS SECTIONS - RADIATIVE CORRECTIONS CAN BE SIGNIFICANT.
We have measured the e + e − → ø reaction by its K + K − decay mode. Using our previous results on K O K O and the 3π decay mode of the ø mesons, we compute Γ ø → e + e − and then compare the whole Orsay results to theoretical predictions.
FITTED CROSS SECTIONS AT PHI PEAK. ONLY PHI --> K+ K- MEASURED HERE - ANALYSIS USES PREVIOUS EXPERIMENTS FOR OTHER CHANNELS: J.E. AUGUSTIN ET AL., PL 28B, 517 (1969).
EXCITATION OF K+ K- CHANNEL MEASURED AROUND PHI RESONANCE AT 13 ENERGIES.
We have measured the e + e − → φ reaction by the K S 0 K L 0 and 3 π decay modes of the φ. We have deduced Γ ( φ → all), Γ ( φ →e + e − ), as well as B ( φ →K S 0 K L 0 ), B ( φ →K + K − ) and B ( φ → π + π − π 0 ).
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RESONANCE FIT TO 12 DATA POINTS AROUND PHI FOR EACH CHANNEL GIVES PHI WIDTH OF 4.2 +- 0.9 MEV AND BR(PHI --> PI+ PI0 PI-/PHI --> KL KS) OF 0.667 +- 0.157 (RATHER HIGH).
No description provided.