We have observed τ pair production at average CM energies of 13.9, 22.3, 34.5 and 43.1 GeV. The cross-sections are consistent with QED, the cut off parameters beingΛ+>161 GeV andΛ−169 GeV (95% CL). The topological branching fraction of the τ to 1 charged particle,B1, is 0.847±0.011 (stat)−0.013+0.016(syst) and no decays to 5 charged particles were observed resulting inB5<0.007 (95% CL). Within the 3 charged track final stateB(τ−→π−π+π−v)/(B(τ−→π−π+π−v)+B(τ−→π−π+π−π0v))=0.37−0.20+0.35
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The production of collinear muon pairs has been studied using the JADE detector at thee+e− storage ring at PETRA. Results for the total cross section and the angular distribution were obtained at centre of mass (cm) energies ranging from 12 to 46 GeV. The data correspond to an integrated luminosity offLdt>90 pb−1, of which 71.2 pb−1 were taken at\(\left\langle {\sqrt s } \right\rangle \)=34.4 GeV and 17 pb−1 at\(\left\langle {\sqrt s } \right\rangle \)=42.4 GeV. The results are compared to electroweak theories, in particular the “Standard Model”.
Forward-backward asymmetry calculated from a fit to the angular distribution of the form 1: + cos(theta)**2 + Bcos(theta).. Asymmetries quoted here are extrapolated to full solid angle. The asymmetry at sqrt(s) = 34.4 is -11.10 +- 1.75 +- 1.0 pct if the end-cap points are included.
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The paper presents results on measuring the polarization in the reaction π − p→ π 0 n at 40 GeV/ c in the 4-momentum transfer range 0<| t |⩽2 (GeV/ c ) 2 . The results based on the statistics of about 2.2 million recorded events made it possible to observe a noticeable value and complex structure in the polarization behaviour up to | t |⩽2 (GeV/ c ) 2 .
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The production of electrons by bottom and charm hadrons has been studied in e + e − annihilation at 34.6 GeV center of mass energy. It is observed that the b quark fragmentation function is peaked at large values of the scaling variable z with 〈 z b 〉 = 0.84 +0.15 + 0.15 −0.10 − 0.11 . For c quarks 〈 z c 〉 = 0.57 +0.10 + 0.05 −0.09 − 0.06 is observed. A forward-backward charge asymmetry of A = −0.25 ± 0.22 was measured in b production.
THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT ELECTRONS.
THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT ELECTRONS.
The forward-backward charge asymmetry for the process e + e − → b b ̄ → μ ± + hadrons has been measured using the JADE detector at PETRA. An asymmetry of (−22.8 ± 6.0 ± 2.5)% was observed at an average center of mass energy of 34.6 GeV. For comparison, an asymmetry of −25.2% is expected on the basis of the standard Glashow-Salam-Weinberg model.
THE VALUE OF CONST HAVE BEEN RESCALED TO DEFINITION I3(Q) = 1/2 BY OPY.
Experimental data on the forward-backward asymmetry of π- emission in (d,4He,12C)181Ta interactions atp/A=4.2 GeV/c are presented. The absolute value of the asymmetry coefficient of the inclusive π- production in the nucleon-nucleonCMS decreases asAp−0.35 with increasing atomic mass of projectile nucleus. A method of obtaining the target-to-projectile ratio of the numbers of participant nucleonsNt/Np through measuring the velocity of the symmetric pion emission system is proposed. It has been found that Nt/Np∼Ap−0.73.
IN THE NUCLEON-NUCLEON CENTRE-OF-MASS SYSTEM.
IN THE NUCLEON-NUCLEON CENTRE-OF-MASS SYSTEM.
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