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.
The inclusive yield of photons has been measured from deep inelastic interactions of 200 GeV muons on hydrogen. After subtracting the contributions from hadron electromagnetic decays and Bethe-Heitler muon bremsstrahlung, residual photons are observed at low p T and low z at a mean level of 0.15±0.06 per interaction. The quark Compton scattering process is unable to explain the data, thus indicating an anomalous photon production.
Z distribution of anomalous direct photons.
PT distribution of anomalous direct photons.
The production of\(\bar D\) mesons in neutroncarbon interactions at 40–70 GeV/c has been investigated. The\(\bar D\) mesons were detected via the hadronic decay modes\(\bar D^0\to K^{* + } (892)\pi ^ -\) andD−→K*+(892)π−π−. In the kinematical regionxF>0.5 andpT<1 GeV/c the following inclusive cross sections were measured:\(\sigma _{\bar D^0 }= (28 \pm 14)\mu b\) and\(\sigma _{D^ -}= (28 \pm 13)\mu b\) per carbon nucleus. The invariant longitudinal momentum spectra can be described by (1−x)N with\(N_{\bar D^0 }= 1.1 \pm 0.5 \pm 0.4\) and\(N_{D^ -}= 0.8 \pm 0.4 \pm 0.4\) The transverse momentum spectra were parametrized by exp (−BpT2) with\(B_{\bar D^0 }= (1.2_{ - 0.9}^{ + 1.1} )({{GeV} \mathord{\left/ {\vphantom {{GeV} c}} \right. \kern-\nulldelimiterspace} c})^{ - 2} \) and\(B_{D^ -}= (1.8_{ - 1.0}^{ + 1.3} )({{GeV} \mathord{\left/ {\vphantom {{GeV} c}} \right. \kern-\nulldelimiterspace} c})^{ - 2} \).
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A comparison is made between the properties of the final state hadrons produced in 280 GeV μp interactions and ine+e− annihilation. The Lund model of hadroproduction is used as an aid in understanding the differences observed. The hadron distributions from μp ande+e− interactions are consistent with the quark parton model assumption of environmental independence, provided that the differences in heavy quark production and hard QCD effects in the two processes are taken into account. A comparison with aK+p experiment is also made. Values are also determined for the Lund model parameters σq = 0.410 ± 0.002 ± 0.020 GeV and σ′ = 0.29−0.15 −0.13+0.09+0.10 GeV, controlling the transverse momenta in fragmentation and intrinsic transverse momenta of the struck quark respectively.
With respect to the virtual photon axis.
With respect to the sphericity axis.
With respect to the thrust axis.
We have observed the production of\(\bar D^0 \) andD− mesons in neutron carbon interactions at 40–70 GeV/c. The experiment was performed with the spectrometer BIS-2 located in the neutron beam 4N of the Serpukhov accelerator.
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CORRECTED FOR ACCEPTANCE. AUTHORS NAMED THIS SPECTRUM 'INVARIANT'.
We present an experimental study of jetproduction in photon-photon interactions for 0.1≲Q2≲120 GeV2 and jet transverse momentum,pT, up to 5 GeV/c. At alQ2, the data show a highpT, tail, characteristic of a point-like interaction. The jet production cross-section approaches the quarkparton model (QPM) expectation as either jetpT orQ2 increases. Overall, the data are well described in both total cross-section and event topology by the sum of a vector-dominance model and a point-like interaction, represented by the QPM.
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In this paper, results are presented from a study of the hadronic final states in e+e− annihilation at 29 GeV. The data were obtained with the High Resolution Spectrometer (HRS) at the SLAC PEP e+e− colliding-beam facility. The results are based on 6342 selected events corresponding to an integrated luminosity of 19.6 pb−1. The distributions of the events in sphericity (S), thrust (T), and aplanarity (A) are given and compared to other e+e− data in the same energy range. We measure 〈S〉=0.130±0.003±0.010 and 〈1-T〉=0.100±0.002. The sphericity distribution is compared to sphericity measurements made for beam jets in hadronic collisions as well as jets studied in neutrino scattering. The data sample is further reduced to 4371 events with the two-jet selections, S≤0.25 and A≤0.1. The single-particle distributions in the longitudinal and transverse directions are given. For low values of the momentum fraction (z=2p/W), the invariant distribution shows a maximum at z∼0.06, consistent with a QCD expectation. The data at high Feynman x (xF) show distribution consistent with being dominated by a (1-xf)2 variation for the leading quark-meson transition. The rapidity distribution shows a shallow central minimum with a height (1/NevdNh/dY‖Y=0=2.3±0.02±0.07. The mean charged multiplicity is measured to be 〈nch〉=13.1±0.05±0.6. The mean transverse momentum relative to the thrust axis 〈pT〉 rises as a function of z to a value of 0.70±0.02 GeV/c for z≳0.3. The distributions are compared to those measured in other reactions.
New values supplied 6.7.87 by M.Derrick.
No description provided.
New values supplied 6.7.87 by M. Derrick.
Light ion collisions with carbon target at 4.2 GeV/c/N are studied. Pion multiplicity distributions, momentum and angular spectra are analysed. These data are described in terms of models assuming independent interactions of nucleons from the projectile nucleus with the target.
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New data on the observation and study of a narrow resonance decaying intoΣ−(1,385)K+ have been obtained. The mass of the resonance is (1,956−6+8) MeV/c2, and its width is (27±15) MeV/c2. The resonance is produced in the diffraction dissociation of neutrons on quasi-free nucleons of carbon nuclei. The slope parameter of the differential cross section inPT2 is (9.9±3.0) (GeV/c)−2. The cross section times the branching ratio is (0.22±0.04) μb per nucleon. The resonance has one of the natural spinparities: 5/2+, 7/2− and so on.
YN IS IN ARBITRARY UNITS.
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ARBITRARY UNITS FOR YN.
New results on the forward produced protons and antiprotons in high energy muon-nucleon scattering are presented. Their W 2 , z and p 2 T dependences are compared with those of the other charged hadrons. Significant differences are observed which can be related to the flavour content of the target and to a difference between the baryon content of quark and gluon jets.
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