Hyperon production at 200 and 900 GeV c.m. energy

The production of Λ's and Ξ-'s in proton-antiproton collisions at 200 and 900 GeV c.m. energy has been studied using decays observed in the UA5 streamer chambers. The results are compared to previously published 546 GeV data, to results from other experiments, and to four theoretical models. The Λ yield per inelastic event is estimated to be 0.42±0.11 at 200 GeV and 0.66±0.14 at 900 GeV. We find a mean number of Ξ-'s per inelastic collision of 0.03-0.02+0.04 at 200 GeV and 0.06-0.03+0.05 at 900 GeV. The average transverse momentum of Λ's in the rapidity region0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Kaon production at 200 and 900 GeV CM energy

0info:eu-repo/semantics/publishe

Kaon production in antiproton-proton interactions at c.m. energies from 200 to 900 GeV

A detailed analysis of Ks0 production in {Mathematical expression}0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Charged particle multiplicity distributions at 200 and 900 GeV c.m. energy

Multiplicity distributions of charged particles produced in non single-diffractive collisions between protons and antiprotons at centre of mass energies of 200 and 900 GeV are presented. The data were recorded in the UA5 streamer chambers at the CERN Collider, which was operated in a pulsed mode between the two energies. A new method to correct for acceptance limitations and inefficiencies based on the principle of maximum entropy has been used. Multiplicity distributions in full phase space and in intervals of pseudorapidity are presented in tabular form. The violation of KNO scaling in full phase space found by the UA5 group at an energy of 546 GeV is confirmed also at 200 and 900 GeV. The shape of the 900 GeV distribution in full phase space is narrower in the peak region than at 200 GeV but exhibits a pronounced high multiplicity tail. The negative binomial distribution fits data at 200 GeV in all pseudorapidity intervals and in small intervals at 900 GeV. In large intervals at 900 GeV, however, the negative binomial distribution. Fits to the partially coherent laser distribution are also presented as well as comparisons with predictions of the Dual Parton, the Fritiof and the Pythia models. © 1989 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Charged particle correlations in p¯p collisions at c.m. energies of 200, 546 and 900 GeV

We present data on two-particle pseudorapidity and multiplicity correlations of charged particles for non single-diffractive {Mathematical expression} at c.m. energies of 200, 546 and 900 GeV. Pseudorapidity correlations interpreted in terms of a cluster model, which has been motivated by this and other experiments, require on average about two charged particles per cluster. The decay width of the clusters in pseudorapidity is approximately independent of multiplicity and of c.m. energy. The investigations of correlations in terms of pseudorapidity gaps confirm the picture of cluster production. The strength of forward-backward multiplicity correlations increases linearly with in s and depends strongly on position and size of the pseudorapidity gap separating the forward and backward interval. All our correlation studies can be understood in terms of a cluster model in which clusters contain on average about two charged particles, i.e. are of similar magnitude to earlier estimates from the ISR. © 1988 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Diffraction dissociation at the CERN pulsed pp collider at c.m. Energies of 900 and 200 GeV

Cross-sections for diffractive particle production and pseudorapidity distributions of the decay products of diffractive states are presented. The data were obtained with the UA 5 streamer chamber detector at the CERN pp Collider operated in a new pulsed mode yielding pp interactions at c.m. energies of 900 and 200 GeV. Data recorded with a special trigger designed to select a sample of events enriched in single-diffractive interactions clearly favour a pt-limited fragmentation of diffractive states. The cross-section for single-diffractive particle production ϊ was found to be 7.8±0.5±1.1 mb at 900 GeV and 4.8±0.5±0.8 mb at 200 GeV (first error statistical, second systematic). From the pseudorapidity distribution of diffractive states we deduce the average number of charged particles to be 6.5±1.0 at 900 GeV and 4.1±1.1 at 200 GeV. Furthermore we report on our estimates for the cross-section of double-diffractive particle production at both Collider energies. © 1986 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Photon production at c.m. energies of 200 and 900 GeV

We present data on photon production in non single-diffractive p {Mathematical expression}-collisions at c.m. energies of 200 and 900 GeV. Besides the general properties of photon production, i.e. pseudorapidity distribution and average multiplicity, we also investigate photon-charged two-particle pseudorapidity and multiplicity correlations. We find for the average number of photons in non single-diffractive p {Mathematical expression}-collisions 22.2±1.4±2.0 at 200 GeV and 41.4±2.1±3.5 at 900 GeV, where the first error is statistical and the second systematic. The analysis of photon-charged particle multiplicity correlations reveals strong positive correlations between the average number of photons and the number of simultaneously produced charged particles, as expected from FNAL and ISR studies and from our result at 546 GeV. We obtain for the correlation slope 0.95±0.08±0.11 at 200 GeV and 1.09±0.09±0.13 at 900 GeV (first error is statistical and the second systematic). The investigation of photon-charged two-particle pseudorapidity correlations shows that these correlations are of short range and compatible with the observed charged two-particle pseudorapidity correlations. These correlations and the results for the average number of photons as a function of the produced number of charged particles favour the conclusion that photon sources other than π0 s contribute significantly to the observed photon yield in non single-diffractive p {Mathematical expression}-collisions. For example, if all photons are assumed to come from π0 s and η mesons, a η/π0 ratio of about 20% is inferred. © 1989 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Charged Particle Multiplicity Distributions in Restricted Rapidity Intervals in Z0 Hadronic Decays

The multiplicity distributions of charged particles in restricted rapidity intervals in Z0 hadronic decays measured by the DELPHI detector are presented. The data reveal a shoulder structure, best visible for intervals of intermediate size, i.e. for rapidity limits around ±1.5. The whole set of distributions including the shoulder structure is reproduced by the Lund Parton Shower model. The structure is found to be due to important contributions from 3-and 4-jet events with a hard gluon jet. A different model, based on the concept of independently produced groups of particles, "clans", fluctuating both in number per event and particle content per clan, has also been used to analyse the present data. The results show that for each interval of rapidity the average number of clans per event is approximately the same as at lower energies. © 1991 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe