Soft Hadronic Collisions Research Articles

Charged particle multiplicity distributions ine + e − annihilation at 29 GeV: a comparison with hadronic data

The charged particle multiplicity distributions for two-jet events ine + e − annihilation at 29 GeV have been measured using the High Resolution Spectrometer at PEP. A Poisson distribution describes the data for both the complete event and for the single jets. In addition, no correlation is observed between the multiplicities in the two jets of an event. For fixed values of the prong number of the complete event, the multiplicity sharing between the two jets is in good agreement with a binomial distribution. The rapidity gap distribution is exponential with a slope equal to the mean rapidity density. These observations, which are consistent with a picture of independent emission of single particles, are contrasted to the results from soft hadronic collisions and conclusions are drawn about the nature of clusters.

Study of quark fragmentation in e+e- annihilation at 29 GeV: Charged-particle multiplicity and single-particle rapidity distributions.

This paper presents the charged-particle multiplicity distributions for e+e− annihilation at √s =29 GeV measured in the High Resolution Spectrometer. The data, which correspond to an integrated luminosity of 185 pb−1, were obtained at the SLAC e+e− storage ring PEP. The techniques used to correct the observed prong numbers are discussed. The multiplicity distribution of the charged particles has a mean value 〈n〉=12.87±0.03±0.30, a dispersion D2=3.67±0.02±0.18, and an f2 moment of 0.60±0.02±0.18. Results are also presented for a two-jet sample selected with low sphericity and aplanarity. The charged-particle distributions are almost Poissonian and narrower than have been reported by other e+e− experiments in this energy range. The mean multiplicity increases with the event sphericity, and for the sample of threefold-symmetric three-jet events, a value of 〈n〉=16.3±0.3±0.7 is found. No correlation is observed between the multiplicities in the two hemispheres when the events are divided into two jets by a plane perpendicular to the thrust axis. This result is in contrast with the situation in soft hadronic collisions, where a strong forward-backward correlation is measured. For the single jets, a mean multiplicity of 6.43±0.02±0.15 and a dispersion value of D2=2.55±0.02±0.13 are found. These values give further support to the idea of independent jet fragmentation. The multiplicity distributions are well fit by the negative-binomial distribution. The semi-inclusive rapidity distributions are presented. Comparisons are made to the measurements of charged-particle multiplicities in hadron-hadron and lepton-nucleon collisions.Received 12 May 1986DOI:https://doi.org/10.1103/PhysRevD.34.3304©1986 American Physical Society

Charge distributions and correlations in fragmentation models for soft hadron collisions

Data on charge distributions and charge correlations inpp and meson-proton interactions atPS andSPS energies are successfully compared with the Lund fragmentation model for low-PT hadron collisions. It is argued that local conservation of quantum numbers and resonance production, as implemented in fragmentation models, are sufficient ingredients to explain most of the available experimental results at these energies. No necessity is found for dual-sheet contributions considered in DTU-based parton models.

Hadronization by color bremsstrahlung

Particle production in the central plateau of hadronic final states is calculated in a perturbative QCD model. We assume that the controlling process is bremsstrahlung of gluons. We find important differences between the spectrum produced in soft hadronic collisions and the spectrum in e+e annihilation. Describing soft hadronic collisions with the Low-Nussinov model, we find that the central plateau is independent of total energy, but depends strongly on the momentum transfer in the soft-gluon exchange. In contrast, the quark jets from e+e annihilation have a central plateau growing with energy. The strong momentum dependence in the hadron-induced plateau arises from the cancellations in the amplitude associated with the gauge invariance of the theory.

Smooth interpolation between orear-and fixed angle scaling behaviour of the scattering amplitude

A unified picture of both soft and hard hadronic collisions is suggested. The basis idea is to use Regge trajectories of the type $$\alpha (t) = \alpha (0) - \gamma ln (1 + \beta \sqrt {t_0 - t} )$$ in dual models with Mandelstam analyticity. The idea is applied to elastic proton-proton scattering to derive kinematical boundaries of the asymptotic (Regge-t R and scaling-S sc.,t sc.) regimes, to fix the angular dependence in the scaling-and thet-dependence in the Regge domain of the scattering amplitude and to interpolate between the two asymptotic domains.

Hadron distributions in quark jets

We explore the possibility that the longitudinal hadron distributions in quark jets and in soft hadron collisions are similar. Plausibility arguments for this are given in the parton picture of Feynman. It leads to specific predictions for the behaviour of fragmentation functions in the z → 1 and z → 0 limits in terms of Regge trajectory intercepts. Quantum number effects and correlation lengths are discussed. Our results imply a monopole behaviour for the pion form factor, while that of the proton is consistent with a dipole.

Quark dynamics in soft hadronic collisions and fragmentation on nuclear targets

Additive and collective pictures of quark dynamics in hadron-hadron collisions lead to different predictions for attenuation effects on nuclear targets and can be distinguished experimentally.

Introduction to the History of Mycology. Geoffrey C. Ainsworth

Previous articleNext article No AccessBook ReviewsIntroduction to the History of Mycology. Geoffrey C. Ainsworth Frank N. Egerton IIIFrank N. Egerton III Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Isis Volume 68, Number 4Dec., 1977 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/351892 Views: 2Total views on this site Citations: 1Citations are reported from Crossref Copyright 1977 History of Science Society, Inc.PDF download Crossref reports the following articles citing this article:Johannes Ranft Particle Production in Soft and Hard Hadronic Collisions. Is There Evidence for Hadronic Constituents?, (Jan 1980): 241–267.https://doi.org/10.1007/978-1-4684-3602-0_9