Topological distributions of charged and neutral hadrons from the reaction e + e − → multihadrons are studied at √ s of about 30 GeV. An excess of planar events is observed at a rate which cannot be explained by statistical fluctuations in the standard two-jet process. The planar events, mostly consisting of a slim jet on one side and a broader jet on the other, are shown actually to possess three-jet structure by demonstrating that the broader jet itself consists of two collinear jets in its own rest system. Detailed agreement between data and predictions is obtained if the process e + e − →q q ̄ g is taken into account. This strongly suggests gluon bremsstrahlung as the origin of the planar three-jet events. By comparison of the data with the qq̄g-model we obtain a value for the strong coupling constant of α S ( q 2 = 0.17 ± 0.04.
THRUST AND PLANARITY DISTRIBUTIONS. FINAL (BETTER) THRUST DISTRIBUTIONS WITH DETECTOR CORRECTIONS TO BE PUBLISHED LATER.
No description provided.
None
No description provided.
DATA FOR EVNENT WITHOUT PAIRS FROM INTERFIERENCE REGION - YF 27, 1556.
No description provided.
Hadron production by e + e − annihilation has been studied for c.m. energies W between 13 and 31.6 GeV. As a function of 1n W the charged particle multiplicity grows faster at high energy than at lower energies. This is correlated with a rise in the plateau of the rapidity distribution. The cross section s d σ /d x is found to scale within ±30% for x > 0.2 and 5 ⩽ W ⩽ 31.6 GeV.
CHARGED PARTICLE MULTIPLICITIES.
RAPIDITY DISTRIBUTION.
RAPIDITY DISTRIBUTION.
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.
The ratio R of the differential cross sections for π - p→ η ′n and π - p → η n has been measured with high statistics and small systematic errors at 8.45 GeV/ c . R is generally interpreted as the relative content of nonstrange, ground-state quarks in η' and η. We find that R decreases with increasing ⋎ t ⋎; however, extrapolation to t =0 gives R (0) = 0.672 ± 0.032 (statistical) ± 0.47 (systematic) for the dominant spin flip cross sections, and R (0) = 0.500 ± 0.035 for the spin non-flip, in excellent agreement with results at higher energy. An improved value of the branching fraction ( η '→ γγ )/( η '→all) of 0.0200 ± 0.0018 is obtained.
No description provided.
No description provided.
Measurements ofR, sphericity and thrust are presented for c.m. energies between 12 and 31.6 GeV. A possible contribution of at\(\bar t\) continuum can be ruled out for c.m. energies between 16 and 31 GeV.
No description provided.
None
No description provided.
No description provided.
No description provided.
None
292+-7 MUB - CORRECTED VALUE FOR FIRST REACTION (SLOW PROTONS). M(P 4PI) <= 3.5 GEV FOR REACTIONS WITH FOUR PIONS.
No description provided.
No description provided.
We report the measurement of the reaction e + + e − → hadronic jets at a center-of-mass energy √ s =30 GeV using the MARK-J detector at PETRA. By measuring the energy and angular distribution of both neutrals and charged particles we were able to isolate unambiguously the three-jet events in a kinematic region where the backgrounds from q q and phase space contributions and other processes are small. Various comparisons of the data with quantum chromodynamics were made. The relative yield of three-jet events and the shape distribution of the events enable us to determine α s = 0.23 ± 0.02 (statistical error) with a systematic error of ± 0.04.
OBLATENESS AND THRUST DISTRIBUTIONS FOR NARROW AND BROAD JETS AT 30 GEV. THESE DATA ARE SOMEWHAT ANALYSIS AND DETECTOR DEPENDENT.
No description provided.
We observe production of a Ξ * (2370) in the reactions K − p→ [YK¯π] K, [YK¯π] Kπ and [ΩK] (K or Kπ) at 8.25 GeV/ c in a high statistics bubble chamber experiment. The mass and width are determined to be 2373 ± 8 MeV and 80 ± 25 MeV, respectively. The I = 1/2 assignment is strongly favoured.
CROSS SECTIONS FOR PRODUCTION OF XI(2370) --> (LAMBDA + SIGMA) AK PI. BREIT-WIGNER FIT WITH POLYNOMIAL BACKGROUND. XI(2370) PRODUCED BY BARYON EXCHANGE. CORRECTED FOR NEUTRAL DECAYS AND GEOMETRICAL LOSSES. <OMEGA-KAON> DECAY SEEN. OBSERVED RATIO OF CHARGED TO NEUTRAL XI(2370) PRODUCTION IS 2.7 +- 0.9.
Forum