T. Muller

Multiplicity distributions in different pseudorapidity intervals at a CMS energy of 540 GeV

Abstract Multiplicity distributions of charged particles for inelastic, non single-diffractive events in proton-antiproton collisions at a centre of mass energy of 540 GeV are presented for various pseudorapidity (Δη) intervals. The widths of the multiplicity distributions, scaled to their means, increase as Δη is made smaller, and the deviation from a Poisson distribution becomes progressively more pronounced. It is found that the data are remarkably well described by a negative binomial distribution. The parameters of the distributions vary smoothly with the size of the acceptance interval.

A new empirical regularity for multiplicity distributions in place of KNO scaling

Abstract Charged particle multiplicity distributions for the inelastic, non-single-diffractive component of p p reactions at 540 GeV CMS energy and of pp reactions above about 10 GeV are shown to be remarkably well described by a negative binomial distribution at each energy. The two parameters of the distribution depend on energy in a regular manner, which affords the possibility of predicting multiplicity distributions at high energies not yet experimentally available. In this description there is a complete absence of any tendency to approach asymptotic KNO scaling below 540 GeV. The approximate scaling in the CM energy range 10–62 GeV is shown, in this framework, to be accidental.

First results on complete events from pp collisions at the cm energy of 540 GeV.

Abstract First results from the UA5 detector on charged particle production at √s = 540 GeV in the pseudorapidity range ∣ν∣

Particle multiplicities in pp interactions at √s=540 GeV

Abstract We present the charged multiplicity distribution in p p interactions at √ s =540 GeV. Moments of the distribution are given, and compared with KNO scaling predictions. An estimate of the particle composition at collider energies is also made.

Production of photons and search for Centauro events at the SPS collider

Abstract The pseudorapidity distribution of photons produced in pp interactions at s =540 GeV has been measured and compared with that of charged particles. The correlation between photon and charged-particle production has been studied. A search amongst high multiplicity events for any having the properties of the Centauro events reported in cosmic-ray experiments has revealed no candidates in a sample of 3600 inelastic events.

Kaon Production in

Abstract Using the UA5 detector, the inclusive central production of Ks0 and K± mesons has been measured in non-single-diffractive interactions at the CERN SPS p p Collider at a c.m. energy of 540 GeV. The average transverse momentum is found to be 〈pT〉 = 0.57±0.03 GeV/c in the rapidity range |y|

\bar{p} p

Abstract First results from UA5 on charged particle multiplicities from p p interactions at √s = 540 GeV are presented. A value of 27.4 ± 2.0 is obtained for the mean charged multiplicity 〈nch〉 of produced hadrons. This excludes an s 1 4 behaviour of 〈nch〉 in going from ISR to Collider energies, but is not in disagreement with an extrapolation using a quadratic fit in ln s to previous lower energy data up to ISR energies.

Reactions at a Center-of-mass Energy of 540-{GeV}

Abstract Results on correlations in charged multiplicity are presented using data from the UA5 detector at the CERN SPS collider. Both short-range and long-range correlations are observed. Our analysis gives no evidence for intrinsic long-range correlations. The observations are consistent with a physical picture in which small clusters are emitted at random along the rapidity axis in the plateau region. This result may indicate that random soft processes play a dominant role in high energy hadronic collisions. The average cluster size is about 2 charged particles, the same as at ISR energies. No variation of cluster size with multiplicity has been observed. The forward-backward long-range correlation and its energy dependence are related to the ratio of the first two moments, variance/mean, of the multiplicity distributions.

Charged particle multiplicities at the CERN SPS collider

Abstract First results are presented on kaon and lambda yields in pp collisions at s =540 GeV . Our data show an increase in the K π ratio and especially in kaon mean transverse momentum relative to results at lower energies.

Forward-backward multiplicity correlations in pp-collisions at s = 540 GeV

Abstract Results are presented from the first p p colliding beam runs at the CERN ISR, using the UA5 streamer chamber detector. p p interactions at s = 53 GeV are compared with pp data taken in the same experiment. The results are in good agreement with extrapolations of low-energy p p data.