The reaction γγ→K + K − π + π − π 0 has been observed for the first time, using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The cross section shows an enhancement for W γγ close to 3 GeV/ c 2 . Searches for γγ→ωφ and for γγ→φφ leading to this final state, as well as for γγ→φφ→2K + 2K − , have been performed. The derived upper limits for ωφ and φφ production are compatible with q q q q model predictions.
TOPOLOGICAL CROSS SECTION.
95 PCT CL UPPER LIMITS.
The reactionγγ→3π+3π- has been studied usig the JADE detector at PETRA. The topological cross sectionσ(γγ→3π+3π-) was measured in the CM energy range 1.5–5.5 GeV. The production ofρ0,s was observed and the average number ofρ0,s per event measured. The contributions of the subprocessesγγ→ρ02π+2π-,γγ→ρ0ρ0π+2π- andγγ→ 3π+3π- (phase space) were studied and 95% C.L. upper limits for the cross sectionσ(γγ→ρ0ρ0π+π- determined. Finally the Bose-Einstein correlation for pairs of like signed pions was observed. A fit to a standard parametrization gave results consistent with other studies of this effect in pion systems.
Topological cross section.
Fractions of events for different final states resulting from the extended liklihood fit using incoherent weights.
Fractions of events for different final states resulting from the extended liklihood fit using coherent weights.
We have measured cross sections, rapidity and transverse momentum distributions, and vector meson polarization for the reactions pp→ ϱ o +anything, pp→ ω +charged particles, and pp → K ∗± + anything at incident laboratory momenta of 12 and 24 GeV/ c . We discuss various consequences of our results as well as possible connections with lepton pair production.
No description provided.
DATA OBTAINED FROM FIGURE BY A.A. LEBEDEV.
DATA OBTAINED FROM FIGURE BY A.A. LEBEDEV.
Virtual photoproduction of J/ ψ mesons has been measured for 280 GeV muon iron interactions in an iron/scintillator calorimeter target. The J/ψ's were identified by their decay into muon pairs. 315 events were observed, about half of which were elastic. The t , Q 2 and v distributions of these elastic events are presented. The v dependence is measured between 40 and 180 Mev and compared with lower energy photoproduction results. The Q 2 dependence is compared with the predictions of the vector dominance model.
TPRIME DISTRIBUTION OF ELASTIC J/PSI EVENTS FOR ALL Q2 AND NU WITH 280 GEV MUON BEAM.
NORMALIZED Q**2 DISTRIBUTION OF ELASTIC J/PSI EVENTS FOR ALL NU AND T WITH 280 GEV MUON BEAM.
EXTRAPOLATION OF Q**2 AND T DEPENDENCE TO CALCULATE D(SIG)/DT AT Q**2=0 AND T=0 FOR ELASTIC J/PSI PHOTOPRODUCTION PER NUCLEON.
We present new high statistics data on hadron production in photon-photon reactions. The data are analyzed in terms of an electron-photon scattering formalism. The dependence of the total cross section of Q 2 , the four-momentum transfer squared of the scattered electron, and on the mass W of the hadronic system is investigated. The data are compared to predictions from Vector-Meson Dominance and the quark model.
No description provided.
DEPENDENCE ON VISIBLE HADRONIC INVARIANT MASS.
Data read from graph.
Using data taken at PETRA we present results on deep inelastic electron photon scattering at momentum transfers 1 < Q 2 < 15 GeV 2 . The results are expressed in terms of the photon structure function F 2 and are compared with QCD predictions and “hadronic” models of the photon. The pointlike component of the photon is found to be dominant.
Data read from graph.. Data for W < 3.5 in Berger et al. 1981, PL 99B,287 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1164> RED = 1164 </a>).
PHOTON STRUCTURE FUNCTION. NUMERICAL VALUES OF DATA ON FIGURE SUPPLIED BY W. WAGNER.
We have measured the production cross section for K s 0 in e + e − annihilation from 3.6 to 5.0 GeV center of mass energy. A substantial increase of the K s 0 yield is observed around 4 GeV in qualitative agreement with the charm hypothesis.
THE DATA GIVEN HERE AT 9.3 GEV AND ABOVE ARE REPORTED IN C. BERGER ET AL., PL 104B, 79 (1981). THE 12.0 AND 30 GEV DATA WERE TAKEN AT PETRA.
No description provided.
No description provided.
None
D* FRAGMENTATION FUNCTION.
R VALUE IS RADIATIVELY CORRECTED (BUT NOT CROSS SECTION).
Production of the F meson by e + e − annihilation at high energies has been obsrved in the ϕπ final state with a mass of 1.975 ± 0.009 ± 0.010 GeV and a width consistent with the mass resolution. The yield of F production times branching ratio relative to μ pair production is R F ( x ⩾ 0.3) B (F ± → ϕπ ± ) = 0.061 ± 0.012 ± 0.018.
No description provided.
CROSS BETWEEN X BRANCHING RATIO DETERMINATION. EXTRAPOLATION BELOW X=0.3 IS USED.
We present an analysis ofρ0ρ0 production by two photons in theρ0ρ0 invariant mass range from 1.2 to 2.0 GeV. From a study of the angular correlations in the process γγ→ρ0ρ0→π−π+π− we exclude a dominant contribution fromJP=0− or 2− states. The data indicate sizeable contributions fromJP=0+ for four pion massesM4π<1.7 GeV and fromJP=2+ forM4π>1.7 GeV. The data are also well described by a model with isotropic production and uncorrelated isotropic decay of theρ0,s. The cross section stays high below the nominalρ0ρ0 threshold, i.e.M4π<1.5 GeV. The matrix element forρ0ρ0 production is found to decrease steeply with increasingM4π. Upper limits for the couplings of the ι(1440) and Θ(1640) to γγ andρ0ρ0 are given:Γ(ι→γγ)·B(ι→ρ0ρ0)<1.0 keV andΓ(Θ→γγ)
ASSUMING ISOTROPIC RHO0 RHO0 PRODUCTION AND ISOTROPIC RHO DECAY.
CROSS SECTIONS FOR DIFFERENT SPIN-PARITY CONTRIBUTIONS.
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