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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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)%.
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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.
Results are presented of an untagged e + e − → e + e − + π + π − experiment performed at PEP with the DELCO detector. In the invariant-mass range 0.7 ⩽ W ππ < 2.0 GeV/ c 2 , the QED e + e − background is identified and eliminated, and both the π + π − predictions and the μ + μ − and K + K − background substractions are normalized to the measurement of the e e + e − events. The results agree with a simple model of superposition and interference of the f 0 (1270) resonance, produced with helicity 2, with a Born-term continuum. From a fit of the model to the data, the radiative width of the f 0 is determined to be Γ f 0 → γγ = 2.70 ± 0.21 keV.
Data read from graph.
Using the ARGUS detector at DORIS we have obtained evidence for a resonance which decays into an F meson and a photon. The observed mass is 2109 ± 9 ± 7 MeV, which is 144 ± 9 ± 7 MeV greater than the F meson mass. Its properties are consistent with those of the F ∗ meson with J P = 1 − .
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RHO0 CROSS SECTION HAS BEEN EXTRAPOLATED OUTSIDE TO 0.1 < X < 0.7 RANGE.
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Jet production properties at s = 540 GeV have been measured in the UA2 detector at the CERN p p Collider. Results on the total transverse momentum of the jet system, on the parton density in the nucleon (structure function) and on the two-jet angular distributions are reported. The data are compared with QCD predictions and extrapolations from lower energy experiments.
DISTRIBUTION OF THE SCATTERING ANGLE OF THE 2-JET AXIS IN THE 2-JET COM FRAME WITH A NORMALISATION FIXED AT 1 FOR COS(THETA*) = 0.
STRUCTURE FUNCTION IS DEFINED AS F(X) WHERE D3(SIG)/DX1/DX2/DCOS(THETA) = (F(X1)/X1)*(F(X2)/X2)*D(SIG)/DCOS(THETA).
The production of K 0 s, Λs and Λ s has been studied in a 280 GeV muon-proton scattering experiment with almost complete coverage of all kinematic regions. A study is made of the dependence of the multiplicities on the hadronic centre of mass energy, W , and of the Feynman x distributions. It is found that K 0 and Λ production is mostly central and increases strongly with W , whereas Λ production comes mainly from the remnant target system and is only weakly W dependent.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
AVERAGE VALUES OF VARIABLES ARE <Q**2>=12GEV**2 , <NU>=76GEV , <W**2>=130GEV**2 , <X BJ>=0.11.
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