UPPER LIMITS FOR DEL(1232)++ PRODUCTION.
UPPER LIMITS FOR SIG(1385)+- PRODUCTION.
A study of charged charm production is made at 400 GeV incident energy of protons in nuclear emulsion. A total of 7005 primary stars have been scrutinized to look for charm particle decays in the forward cone within a decay distance of 100–1,000 μm (3,056 stars) and 100–2,000 μm (3,949 stars). In all 10 charm candidates decaying to 3 charged particles plus neutrals have been observed. Background due to secondary interactions for events of such topology is estimated to be ≈3. Background due to strange particle decays is estimated to be negligible. The rest of the events are attributed toΛc+ andD± decays. This leads to a value of 91±35 μb/nucleon for the total charged charm production cross section. Using production cross section forD± from other experiments we obtainΛc+ production cross section as 62±27 μb/nucleon. Two cases of pair production of charm have been seen.
Axis error includes +- 0.0/0.0 contribution (NOT GIVENDECAY-BR(BRN=D+ --> 3CHARGED (NEUTRALS), BR=0.5)//DECAY-BR(BRN=D- --> 3CHARGED (NEUTRALS), BR=0.5)//DECAY-BR(BRN=LAMBDA/C+ --> 3CHARGED (NEUTRALS), BR=0.6)).
Axis error includes +- 0.0/0.0 contribution (NOT GIVENDECAY-BR(BRN=D+ --> 3CHARGED (NEUTRALS), BR=0.5)//DECAY-BR(BRN=D- --> 3CHARGED (NEUTRALS), BR=0.5)//DECAY-BR(BRN=LAMBDA/C+ --> 3CHARGED (NEUTRALS), BR=0.6)).
An experimental investigation of the reaction γ p → p p p at photon energies 4.7 ⩽ E γ ⩽ 6.6 GeV is described. The main results are the measurement of the cross section as a function of energy, a discussion of the main dynamical features of the reaction and the observation of a narrow p p mass state at 2.024 ± 0.005 GeV with a width of 29 ± 13 MeV.
OBSERVATION OF THIS CHANNEL AS A CONSISTENCY CHECK ON THE NORMALIZATION.
No description provided.
MEASUREMENTS OF CROSS SECTIONS OF MASS SIGNALS AT 1.94 AND 2.024 GEV, EVALUATE BY FITTING TWO BREIT WIGNERS AND CONSTANT BACKGROUND TO (AP P) MASS SPECTRUM. ERRORS ARE STATISTICAL ONLY.
Antiproton helium reaction cross section has been measured at 179.6 MeV with a self shunted streamer chamber in a magnetic field. Charged prong multiplicity, branching ratios and 3 He production probability are given. Comparison with p 2 H data is performed.
MULTIPLICITY AND CROSS SECTIONS FOR THE INELASTIC EVENTS IN THE AP HE INTERACTIONS.
MULTIPLICITY AND CROSS SECTIONS FOR PIONS.
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RHO0 CROSS SECTION HAS BEEN EXTRAPOLATED OUTSIDE TO 0.1 < X < 0.7 RANGE.
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Based on a sample of 22 four-prong D 0 / D 0 decays produced in hydrogen by 360 GeV/ c π − , we present the following new results: mean lifetime τ = (3.5 −0.9 +1.4 ) x 10 −13 s ; production cross section for x F > 0.0, σ = (10.3 ± 3.5) ωb ; the D → K ± π ± π + π − branching ratio = (7.1 ± 2.5)%.
No description provided.
The total e + e − annihilation onto hadron has been measured at CM energies between 33.00 and 36.72 GeV and between 38.66 and 46.78 GeV in steps of 20 and 30 MeV respectively. The average of the ratio R = σ ( e + e − → hadrons )/ σ is 〈 R 〉=3.85±0.12 and 〈 R 〉=4.04±0.10 for the two energy ranges. The systematic error on 〈 R 〉 is 0.31. Both values are consistent with the expectation for the known coloured quarks u, d, s, c and b. No evidence was found for the production of new quarks. If the largest fluctuation in R is interpreted as a narrow resonance, it corresponds to a product of the electronic width and the hadronic branching ratio Γ ee B had >2.9 keV at the 95% confidence level, well below the value expected for the toponium vector ground state with charge 2 3 e . The observed number of aplanar final states rules out the continuum production of a a new heavy flavour with pointlike cross section up to a CM energy of 45.4 GeV for a quarck charge of 1 3 e . and up to 46.6 GeV for 2 3 e at the 95% confidence level.
ENERGY SCANS IN 20(30) MEV STEPS.
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The inclusive production of photons in\(\bar pp\) interactions has been studied at incident momentum of 12 GeV/c. Topological cross section has been presented and KNO distribution for\(\bar pp\) interactions has been studied. Inclusive cross section for γ production has been measured to be 149.5±8.8 mb. Bulk of these photons come from π0 decays whose cross section has been evaluated independently to be 60.4±7.9 mb. Signals of η and ω have been seen in γγ and π+π-π0 decay modes and their inclusive cross sections have been estimated to be 14.9±8.8 mb and 14.6±7.0 mb respectively. Results on average multiplicities of γ and two particle correlation parameters are presented. Neutral pions seem to be more strongly correlated than the charged pions. The inclusive distributions of the Feynmanx andpT/2 of the photons are compared with expectation from charged pions on the basis of charge independence. Energy dependence of the normalised invariant distributions has been studied. The distribution of the scaling variablez of photons ine+e− and\(\bar pp\) interactions has been compared.
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We have observed the π+π− decay of the ρ′(1600) in the production reaction γp→ρ′p at 20 GeV. Using a calculation which takes into account the interference of the ρ′ with the ρ(770) and a Drell background, we find good evidence that this resonance is a radial excitation of the ρ(770). The background interference strongly distorts the angular distributions predicted by a purely s-channel helicity-conserving production mechanism. We measure m0=(1.55±0.07) GeV/c2 and Γ0=(0.28−0.08+0.03) GeV/c2.
SLOPE VARIATION WITH M(PI+ PI-) IN THE RANGE 0.4 TO 2.5 GEV.
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