Total cross-section data are presented for negative pions, kaons, and antiprotons on protons and deuterons in the momentum range 20 GeV/ c to 65 GeV/ c in 5 GeV/ c steps.
Axis error includes +- 0.0/0.0 contribution.
No description provided.
No description provided.
The total momentum and transverse momentum spectra of electrons in e+e− annihilation at 29 GeV have been measured. The inclusive cross section is determined to be 14.4±1.6±5.2 pb for momenta greater than 2 GeV/c. The average semielectronic branching ratios of charm and bottom quarks are measured to be (6.3±1.2±2.1)% and (11.6±2.1±1.7)%, respectively. The fragmentation function for bottom quarks is determined to be peaked at high z, with 〈z〉b=0.75±0.05±0.04.
PT is the transverse momentum of the muon relative to the event thrust axis.
PT is the transverse momentum of the muon relative to the event thrust axis.
A search has been made for the inclusive production of J ψ (3.1) and ϒ (9.4) mesons in e + e − interactions at 29 GeV, via their decay into two leptons. No signal is observed in the J ψ region, nor in the ϒ region. The limits on the cross sections are σ ( e + e − → ψX ) < 4.4 × 10 −36 cm 2 , and σ ( e + e − → ϒX ) < 4.7 × 10 −36 cm 2 . The same data yield limits on the branching ratios for the b quark BR ( b → ψX ) < 4.9% and BR ( b → ℓ + ℓ − X ) < 0.8%.
No description provided.
No description provided.
Inclusive distributions are presented for final-state π0 and η0 mesons produced in γp interactions. For photon energies from 50 to 130 GeV, both cross sections scale for fractional momenta xF>~0.30. The average transverse momentum for both mesons is approximately constant with energy and equal to 0.51±0.05 GeV/c at large xF. The η0π0 ratio similarly rises from 0.07±0.03 at xF=0.38 to 0.30±0.09 at xF=0.90. The π0 distributions are in good agreement with those seen in the scattering of highly virtual incident photons.
No description provided.
This Letter reports a search for the production by e+e− annihilation of a single photon accompanied by particles that interact only weakly in matter. The search was performed at the SLAC e+e− storage ring PEP (√s =29 GeV) with a new detector, ASP. No unexpected signal was observed. The limit Nν<14 (90% C.L.) is placed on the number of light neutrino species, and the mass of scalar electrons predicted by theories of supersymmetry is constrained to mẽ>51 GeV/c2 (90% C.L.) for mγ̃=0 and degenerate ẽ mass states.
No description provided.
We present evidence for the non-Abelian nature of QCD from a study of multijet events produced in e+e− annihilations from √s =50 to 57 GeV in the AMY detector at the KEK storage ring TRISTAN. A comparison of the three-jet event fraction at TRISTAN to the fraction of the DESY storage ring PETRA shows that the QCD coupling strength αs decreases with increasing Q2. In addition, measurements of the angular distributions of four-jet events show evidence for the triple-gluon vertex.
No description provided.
No description provided.
We present the general properties of multihadron final states produced by e+e− annihilation at center-of-mass energies from 52 to 57 GeV in the AMY detector at the KEK collider TRISTAN. Global shape, inclusive charged-particle, and particle-flow distributions are presented. Our measurements are compared with QCD+fragmentation models that use either leading-logarithmic parton-shower evolution or QCD matrix elements at the parton level, and either string or cluster fragmentation for hadronization.
Rapidity distribution with respect to the Thrust axis.
Charged particle X distribution.
Charged particle PL distribution.
We have measured inclusive distributions for charged particles in hadronic decays of the Z boson. The variables chosen for study were charged-particle multiplicity, scaled momentum, and momenta transverse to the sphericity axes. The distributions have been corrected for detector effects and are compared with data from e+e− annihilation at lower energies and with the predictions of several QCD-based models. The data are in reasonable agreement with expectations.
Mean corrected charged particle multiplicity.
Corrected charged particle X distributions. Errors are statistical and systematic combined.
Corrected charged particle PTIN distributions. Errors are statistical and systematic combined.
We present the charged-particle multiplicity distributions for e+e− annihilation at center-of-mass energies from 50 to 61.4 GeV. The results are based on a data sample corresponding to a total integrated luminosity of 30 pb−1 obtained with the AMY detector at the KEK storage ring TRISTAN. The charged-particle multiplicity distributions deviate significantly from the modified Poisson and pair Poisson distributions, but follow Koba-Nielsen-Olesen scaling and are well reproduced by the LUND parton-shower model.
Fully corrected charged particle multiplicity distributions. Errors for n=2 and 4 are systematic only since these were derived using the LUND 6.3 Monte Carlo normalized to the observations at higher n values.
No description provided.
We present first results on the total photoproduction cross section measurement with the H1 detector at HERA. The data were extracted from low Q 2 collisions of 26.7 GeV electrons with 820 GeV protons. The γp total cross section has been measured by two independent methods in the γp center of mass energy range from 90 to 290 GeV. For an average center of mass energy of 195 GeV a value of σ tot ( γp ) = 159 ± 7 (stat.) ± 20 (syst.) μb was obtained.
Data from tagged sample.
Data from untagged sample.