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.     

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.     

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 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.     

Annihilation and topological cross sections forpp and\bar p p interactions at 200 GeV/c

The results of an analysis of streamer chamber data from the NA5 experiment are presented. Topological cross sections forpp and \(\bar p\) p interactions and strange neutral particle production at 200 GeV/c have been measured and ( \(\bar p\) p?pp) difference cross sections have been determined. Multiplicity moments were calculated.     

Some tests of fragmentation models in exclusive channels inK − p reactions at 32 GeV/c

Experimental data for exclusive channels of multiplicity 4–8 in 32 GeV/cK ^? p reactions are compared with predictions of the Lund model. This leads to the following insights: — Evidence is obtained for azimuthal correlations betweenK ⁺ K ^? pairs and p pairs supporting the Lund fragmenttation scheme. — The disagreement of the observed behaviour of leading protons andK ^? with the model predictions indicates that the fate of the valence quarks is not well described by the model. The data support the idea of valence quark separation as advocated by dual models.     

Cross sections for 4He interaction with protons at 5 GeV/c

The total and topological ⁴Hep cross sections, as well as the cross sections for individual αpinteraction channels and the differential cross sections dσ/dt for elastic αp scattering, were measured by using a 2-m hydrogen bubble chamber exposed to a separated beam of 5-GeV/c α particles from the ITEP synchrotron (the kinetic energy of initial protons in the nuclear rest frame was T _p=620 MeV). The data obtained are compared with the results of previous experiments and with theoretical predictions based on Glauber-Sitenko multiple-scattering theory.     

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.     

Pionization in pp interactions at 12 and 24 GeV/c

Inclusive π⁻ and π⁺ distributions in the region of small longitudinal c.m. momenta, from pp interactions at 12 and 24 GeV/c, are presented and compared with CERN-ISR data. Interesting scaling and factorization properties are found. The extent to which the observed behavior can be interpreted as evidence for pionization is discussed.     

Production of \Xi^* resonances in \Sigma^- induced reactions at 345 GeV/c

The value of the - mixing angle is phenomenologically deduced from a rather exhaustive and up-to-date analysis of data including strong decays of tensor and higher-spin mesons, electromagnetic decays of vector and pseudoscalar mesons, decays into a vector and a pseudoscalar meson, and other transitions. A value of between ° and ° is consistent with the present experimental evidence and the average seems to be favoured. Received: 14 May 1998 / Published online: 6 November 1998     

The description of inclusive characteristics in\bar pp interactions at 22.4 GeV/c in terms of the quark-parton model

We compare the inclusive characteristics of \(\bar pp\) interactions at 22.4 GeV/c with quark-parton model predictions in terms of collective variables. The model qualitatively agrees with the data in contradiction to the simple cylindrical phase space and randomized charge model. The ways are proposed of a further development of the quark-parton model.     

Kaon production in\bar pp interactions at c.m. energies from 200 to 900 GeV

A detailed analysis ofK _s ⁰ production in \(\bar pp\) |<2.5 the average transverse momentum is found to be 0.53±0.07 GeV/c at 200 GeV and 0.62±0.08 GeV/c at 900 GeV, which is an increase with respect to data at c.m. energies below 60 GeV. TheK _s ⁰ production cross sections in inelastic collisions are 29±4 mb at 200 GeV and 63±6 mb at 900 GeV, showing an increase compared to lower energy data. The central kaon density is found to increase as a logarithmic function of energy. At 900 GeV, where statistics are sufficient to allow one to draw conclusions, the average transverse momentum is higher in events with large charged multiplicity than in events with low multiplicity.     

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     

Cross sections for charged current ν and\bar v interactions in the energy range 10 to 50 GeV

Charged-current neutrino and antineutrino interaction cross sections have been measured in the energy range 10 to 50 GeV using BEBC filled with a neon-hydrogen mixture. At these energies, σ/E was measured to be (0.73±0.08) 10^?38 cm²/GeV per nucleon for neutrinos and (0.32±0.06) 10^?38 cm²/GeV per nucleon for antineutrinos.     

Cross sections and multiplicity distributions forK + p interactions at 70 GeV/c

Cross sections and charged multiplicity distributions forK ⁺ p interactions at 70 GeV/c are presented and compared withK ⁺ p data at other energies. Comparisons are also made with available π⁺ p,pp, andK ^? p data.     

A-dependences of neutral strange particle yields in \bar p-nuclei collisions at 40 GeV/c

The interactions of with D, Li, C, S, Cu and Pb nuclei at 40 GeV/c were studied by the RISC-streamer chamber spectrometer. The yields of mesons and and hyperons as functions of the target nucleus mass number are investigated. The experimental results are compared with model predictions using the FRITIOF-7.02 program package. Received: 10 October 1998 / Revised version: 1 April 1999 / Published online: 12 August 1999     

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.