Inclusive production of neutral strange particles in\bar pp interactions at 32 GeV/c

Multiplicities of charged particles produced in the forward and backward hemispheres are investigated for proton-nucleus and proton-nucleon collisions in the range from 20 to 400 GeV/c. Weak, but growing with incident beam momentum, forward-backward multiplicity correlations are observed which cannot be reduced to the inelastic diffraction. These correlations are more pronounced in proton-nucleus than proton-nucleon interactions. The experimental data are discussed in the frameworks of current cluster and multiple scattering models. It is shown that multiple scattering models describe well the forward-backward multiplicity correlations in nuclear production.     

Inclusive production of neutral strange particles in\bar pp interactions at 70 GeV/c

The inclusive production ofK _s ⁰ , Λ and \(\bar \Lambda \) particles is investigated in 70 GeV/c \(\bar pp\) interactions in an experiment performed at CERN using BEBC equipped with a TST. Differential cross-sections are studied and compared with corresponding data at surrounding energies. Differences withpp data obtained at the same energy allow an estimate of theK _s ⁰ , production cross-section in annihilation processes. Evidence is also given for central \(\Lambda \bar \Lambda \) production.     

Production of neutral strange particles inpAr,pXe and\bar pXe collisions at 200 GeV

The production of neutral strange particles (K ⁰, ) inp Ar,pXe and Xe collisions at 200 GeV is investigated in the NA5 experiment using a streamer chamber at the CERN SPS. Results are presented on inclusive cross sections, average multiplicities, and on rapidity and transverse momentum distributions of neutral strange particles.     

Inclusive features of neutral strange particles in \overline p A interactions at 40 GeV/c

Mean inclusive features of neutral strange particles produced in antiproton interactions with D, Li, C, S, Cu, and Pb nuclei at an incident momentum of 40 GeV/c are found as functions of the target mass number.     

Multiplicity of charged secondaries emitted in association with neutral strange particles in antiproton-nucleus collisions at 40 GeV/c

In collisions of 40-GeV/c antiprotons with D, Li, C, S, Cu, and Pb nuclei, mean multiplicities of various secondary particles are investigated as functions of the mass number A. The mass-number dependence of the mean multiplicities of positively charged particles suggests that the effect of intranuclear cascades is strong for the emission of Λ hyperons, but that it is relatively weak for the emission of either K ⁰ or $\bar \Lambda $ . Also measured are the yields of various neutral strange particles with respect to those of charged secondaries.     

Neutral strange particle production in proton-proton collisions at\sqrt s = 63 GeV

The inclusive cross section for the production ofK _s ⁰ mesons, Λ and \(\bar \Lambda\) particles in proton-proton interactions at \(\sqrt s = 63\) GeV is presented. The produced particles have been detected in the full phase space. Behaviour of the longitudinal and transversal depandences of the cross sections are discussed. The total production cross sections for _s ⁰ mesons and Λ particles was determined to \(\sigma _{{\rm K}_S^0 } = (25.5 \pm 1.4)\) mb andσ _Λ =(7.8±1.2) mb respectively. A strong energy dependence of the production cross sections is observed.     

Search for charmed hadrons in neutral strange particle events in pp interactions at 19 GeV/c

A search for charmed hadrons has been made in proton-proton interactions at 19 GeV/c using events with one or two observed neutral strange particles. No evidence for charmed particles has been found. Upper limits for their production cross sections are presented.     

Hyperon production in\bar pp interactions at 22.4 GeV/c

In the present paper we investigate the production of charged hyperons and antihy-perons in p interactions at 22.4 GeV/c recorded in the 2m hydrogen bubble chamber Ludmila. After correction for losses due to the kinematics of hyperon decays and for scanning efficiency we have obtained 610 events with charged hyperons or antihyperons. A total cross section of 1.3 _–0.05 ^+0.4 mb for ^±/ has been obtained, and various associated charged particle multiplicity distributions are presented.We would like to express our gratitude to the Ludmila collaboration for the experimental material and continuous interest in this work. Especially we would express our sincere thanks to Professor I. M. Gramenitskii for his critical comments and fruitful discussions.     

Charged particle correlations in\bar pp 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 \(p\bar p - collisions\) 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 ins 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.     

General features of\bar pp interactions at 7.3 GeV/c

Absolute inclusive cross sections for \(\bar pp\) interactions at 7.3 GeV/c are given. The data cover prong cross sections,V ⁰, γ production and inclusive charged particle (p/π) production. Separation has been made into annihilation and non-annihilation components. Inclusive π⁺, π^? production in the processes of \(\bar pp\) annihilation and non-annihilation are compared with simple quark models.     

Neutral strange particle production inK + p interactions at 32 GeV/c

The production properties ofK _s ⁰ , \(\bar \Lambda\) andK ⁺ p interactions at 32 GeV/c are investigated using the final statistics of the experiment. We present total and semi-inclusive cross sections and aver-age multiplicities. Estimates are given of the diffractive dissociation contributions to total and differential cross sections. Thex-,p _T ^?, and transverse mass dependence of inclusive and semi-inclusive distributions is discussed as well as properties of “prompt”K _s ⁰ 's. The ratio of “prompt”K ₈₉₀ ⁺ (K ₈₉₀ ⁰ ) to “prompt”K ⁰ cross sections is measured to be 1.03±0.12 (0.98±0.17). From a comparison of \(\bar \Lambda\) production inK ^± p interactions at 32 GeV/c, we estimate a strange sea-quark suppression of 0.26 ±0.02. The double differential cross sections ofK _s ⁰ 's is studied as a function of Feynman-x andp _T ² , and a Triple-Regge fit performed. The data are compared in detail to versions of the Lund-model for low-p _T hadronic collisions.     

Baryonic resonance production in\bar p p interactions at 32 GeV/c

The inclusive production of (1232) in \(\bar p\) p interactions at 32 GeV/c is studied using data collected in a bubble chamber experiment with a statistics of ～0.7 events/μb. Total and topological cross sections are evaluated and compared to existing data at other energies. The distributions of reduced longitudinal momentum and rapidity show evidence for some central production. Total cross sections for (∑ ⁺(1385)+cc) and (∑ ^?(1385)+cc) are also presented.     

Cross sections for exclusive channels in\bar pp reactions at 12 GeV/c

The data obtained in an exposure of BEBC to an r.f. separated beam of antiprotons at 12 GeV/c are used to derive exclusive cross sections for reactions having one or more neutral strange particles in the final state. Particular attention is given to the estimation of the background. An upper limit of the cross section for the inclusive production of the charmed mesonD ^* is also given.     

Determination of the total c\bar c production cross section in 340 GeV/c \Sigma^--nucleus interactions

The production of charmed particles by 340 GeV/c momentum was studied in the hyperon beam experiment WA89 at the CERN-SPS, using the -spectrometer. In two data-taking periods in 1993 and 1994 an integrated luminosity of on copper and carbon targets was recorded. From the reconstruction of charm particle decays in 10 decay channels production cross sections for D, , and were determined in the region . Assuming an dependence of the cross section on the nucleon number, we calculate a total production cross section of per nucleon. The last term is an upper limit on the unknown contribution from charmed-strange baryon production. Received: 3 September 1999 / Published online: 3 February 2000     

Inclusive particle production inp\bar p collisions

We calculate the inclusive production of charged hadrons in collisions at the next-to-leading order in the QCD improved parton model using a new set of fragmentation functions for charged pions and kaons. We predict transverse-momentum distributions and compare them with experimental data from the CERN Collider and the Fermilab Tevatron.     

Study of inclusive production of boson resonances in\bar pp-interactions at 32 GeV/c

The inclusive production ofK ^*±(890), ρ^ρ(770), ω⁰(780) andf ⁰(1,270) mesons is studied in \(\bar pp\) experiment at 32GeV/c in the MIRABELLE bubble chamber by the analysis of (K ⁰π^±) and (π⁺π^?) invariant mass distributions. The inclusive cross sections are σ(K ^*±)=2.45±0.30 mb, σ(ρ⁰)=8.8 ±0.9 mb, σ(ω⁺)?6.2 mb, and σ(f ⁰)=2.2±0.7 mb. The C.M. longitudinal distribution of theK ^*±(890) is slightly shifted to the primary particles fragmentation regions; the ρ⁰ is produced more centrally. The studied mesons alone are responsible for 40% of final state poins. The production features of various resonances are compared with quark models predictions.     

Inclusive resonance production in 7.3 GeV/c\bar pp interactions

We present results on inclusive baryon and meson resonance production in \(\bar pp\) interactions at 7.3 GeV/c. Total inclusive and semi-inclusive cross sections are given for Δ(1232),∑ ^*(1385), ?⁰,f andK ^*±(892) production. For the meson resonances separation into annihilation and non-annihilation components has been made, the annihilation component being dominant at this energy. We find that the energy dependence of inclusive cross sections for ?⁰ production inpp interactions and \(\bar pp\) non-annihilations shows a type of scaling behaviour previously reported for ?, ψ, ψ′ and ? production inpp interactions.Δ ⁺⁺, ?⁰ andK ^*± production are studied in terms of Feynmanx,y ^* andp _T ² . For the vector mesons we compare they ^* andx dependences with the predictions of simple quark models.     

Inclusive strange particle production in π−p interactions at 6 GeV/c

The inclusive production of Λ, K_S⁰, Σ^±(1385) and $\text{K}{}^{\mathrm{1\pm }}\text{(892)}$ in π^?p interactions at 6 GeV/c has been studied. The observed cross sections are: σ(Λ)=0.94±0.06 mb, σ(K_S⁰)=0.98±0.06 mb, σ(Σ⁺(1385))=60±7 μb, σ(Σ^?(1385))=90±9 μb, $\text{σ(}\text{K}{}^{\mathrm{1+}}\text{(892))=216±28 μ}\text{b and}\text{σ(}\text{K}{}^{\mathrm{1?}}\text{(892))=41±8 μ}\text{b}$, respectively. The inclusive spectra of these particles are presented as functions of squared transverse momentum and Feynman scaling variable x. The polarization of Λ has also been investigated. It is found from a comparison with higher-energy data that the inclusive cross sections for Σ^±(1385) and the production ratios Σ^±(1385)/Λ in π^?p at 6 GeV/c have not reached the high-energy limiting values.     

Central Pb+Pb collisions at 158 A GeV/c studied by \pi^-\pi^- interferometry

Two-particle correlations have been measured for identified from central 158 A GeV Pb+Pb collisions and fitted radii of about 7 fm in all dimensions have been obtained. A multi-dimensional study of the radii as a function of is presented, including a full correction for the resolution effects of the apparatus. The cross term of the standard fit in the Longitudinally CoMoving System (LCMS) and the parameter of the generalised Yano-Koonin fit are compatible with 0, suggesting that the source undergoes a boost invariant expansion. The shapes of the correlation functions in and have been analyzed in detail. They are not Gaussian but better represented by exponentials. As a consequence, fitting Gaussians to these correlation functions may produce different radii depending on the acceptance of the experimental setup used for the measurement. Received: 3 February 2000 / Published online: 18 May 2000