We present a comprehensive study of the inclusive production of V0V0 pairs (V0=Λ, Λ̄ or KS ) by Σ- and π- of 340 GeV/c momentum and neutrons of 260 GeV/c mean momentum in copper and carbon targets. In particular, the dependence of the xF spectra on the combination of beam-particle and produced V0V0 pair is investigated and compared to predictions obtained from PYTHIA and QSGM calculations. The data and these predictions differ in many details, the agreement can at best be termed as qualitative. A signal from decays of the tensor meson f’2(1525) was observed in the KS KS mass distribution and inclusive production cross sections were measured. No signal was found from the double-strange H-dibaryon decaying to ΛΛ.

We report on the observation of a KSp resonance signal at a mass of 1765 ± 5 MeV/c 2, with intrinsic width Γ = 108 ± 22 MeV/c 2, produced inclusively in Σ--nucleus interactions at 340 GeV/c in the hyperon beam experiment WA89 at CERN. The signal was observed in the kinematic region xF>0.7, in this region its production cross section rises approximately linearly with (1-xF), reaching BR(X→KSp)dσ/dxF=(5.2±2.3)μb per nucleon at xF=0.8. The hard xF spectrum suggests the presence of a strong leading particle effect in the production and hence the identification as a Σ*+ state. No corresponding peaks were observed in the K-p and Λπ± mass spectra.

We report on a high-statistics search for the Theta(1540)(+) resonance in Sigma(-)-nucleus collisions at 340 GeV/c. No evidence for this resonance was found in our data sample which contains 13 million K-s(0)->pi(+)pi(-) decays above background. For the decay channel Theta(+)-> K(s)(0)p and the kinematic range x(F)> 0.05, we find the production cross section to be BR(Theta(+)-> K(s)(0)p)sigma(0)< 1.8 mu b per nucleon at 99% C.L.

M.I. Adamovich, a Yu.A. Alexandrov, b S.P. Baranov, D. Barberis, M. Beck, C. Bérat, W. Beusch, M. Boss, S. Brons, c W. Brückner, M. Buénerd, C. Busch, C. Büscher, F. Charignon, J. Chauvin, E.A. Chudakov, d U. Dersch, F. Dropmann, J. Engelfried, e F. Faller, f A. Fournier, S.G. Gerassimov, 1, g M. Godbersen, P. Grafström, Th. Haller, M. Heidrich, E. Hubbard, R.B. Hurst, K. Königsmann, g I. Konorov, 1, h N. Keller, K. Martens, i Ph. Martin, S. Masciocchi, j R. Michaels, d U. Müller, H. Neeb, D. Newbold, C. Newsom, S. Paul, h J. Pochodzalla, k I. Potashnikova, B. Povh, R. Ransome, Z. Ren, M. Rey-Campagnolle, l G. Rosner, m L. Rossi, H. Rudolph, C. Scheel, L. Schmitt, h H.-W. Siebert, n A. Simon, g V.J. Smith, o O. Thilmann, A. Trombini, E. Vesin, B. Volkemer, K. Vorwalter, Th. Walcher, G. Wälder, R. Werding, E. Wittmann, and M.V. Zavertyaev b

We report on a high statistics search for the ${\ensuremath{\Xi}}^{\ensuremath{-}\ensuremath{-}}(1860)$ resonance in ${\ensuremath{\Sigma}}^{\ensuremath{-}}$-nucleus collisions at $340\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}∕c$. No evidence for this resonance is found in our data sample which contains 676000 ${\ensuremath{\Xi}}^{\ensuremath{-}}$ candidates above background. For the decay channel ${\ensuremath{\Xi}}^{\ensuremath{-}\ensuremath{-}}(1860)\ensuremath{\rightarrow}{\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$ and the kinematic range $0.15<{x}_{F}<0.9$ we find a $3\ensuremath{\sigma}$ upper limit for the production cross section of 3.1 and $3.5\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{b}$ per nucleon for reactions with carbon and copper, respectively.

~The WA89 Collaboration ! Moscow Lebedev Physics Institute, RU-117924 Moscow, Russia Genoa University/INFN, Dipartimento di Fisica, I-16146 Genova, Italy Max-Planck-Institut fu ̈r Kernphysik, Postfach 103980, D-69029 Heidelberg, Germany Grenoble ISN, F-38026 Grenoble, France CERN, CH-1211 Gene `v 23, Switzerland Universität Heidelberg, Physikalisches Institut, D-69120 Heidelberg, Germany Universität Mainz, Institut für Kernphysik, D-55099 Mainz, Germany University of Bristol, Bristol, United Kingdom University of Iowa, Iowa City, Iowa 52242 Rutgers University, Piscataway, New Jersey 08854 NIKHEFF, 1009 D8 Amsterdam, The Netherlands ~Received 21 September 2001; published 5 April 2002 !

We have measured the production of strange baryons and antibaryons in 340-GeV/c Sigma(-)+C and 260-GeV/c n+C interactions. The single x(F) distributions show the expected leading particle effect, and the single p(t)(2) distributions show a distinct nonthermal behavior. The x(F) distributions of Lambda-Lambda pairs indicate two different phase space distributions for the two coincident baryons. On the other hand two (Lambda) over bar 's show identical distributions. Momentum conservation during the formation process may represent a significant source for the observed behavior.

We report on a measurement of the inclusive production cross sections for Z(+/-), Z(1385)(+/-), Z(1660)(+/-) and (Σ) over bar ((1) over bar 385) in the CERN hyperon beam experiment WA89, using a Sigma(-)/pi(-) beam of 345 GeV/c momentum and neutrons of 260 GeV/c mean momentum. A strong leading particle effect was observed for all negative Sigma and Sigma*. The results are compared with predictions from phenomenological models.

The production of charmed particles by 340 GeV/c momentum Σ− was studied in the hyperon beam experiment WA89 at the CERN-SPS, using the Ω-spectrometer. In two data-taking periods in 1993 and 1994 an integrated luminosity of 1600 μb−1 on copper and carbon targets was recorded. From the reconstruction of 930 ± 90 charm particle decays in 10 decay channels production cross sections for D, D, Ds and Λc were determined in the region xF > 0. Assuming an A dependence of the cross section on the nucleon number, we calculate a total cc̄ production cross section of σcc(xF > 0) = 5.3 ± 0.4 (stat) ± 1.0 (syst) + 1.0 (Ξc) μb per nucleon. The last term is an upper limit on the unknown contribution from charmed-strange baryon production. a supported by the Deutsche Forschungsgemeinschaft, contract number436 RUS 113/465, and Russian Foundation for Basic Research under contract number RFFI 98-02-04096. b Now at TRIUMF, Vancouver, B.C., Canada V6T 2A3 c Now at Thomas Jefferson Lab, Newport News, VA 23606, USA d Now at Institudo de Fisica, Universidad San Luis Potosi, S.L.P. 78240, Mexico e Now at Fraunhofer Institut für Solarenergiesysteme, D79100 Freiburg, Germany f Now at Technische Universität München, Garching, Germany g Now at Fakultät für Physik, Universität Freiburg, Germany h Now at Department of Physics and Astronomy, SUNY at Stony Brook, NY 11794-3800, USA i Now at Max-Planck-Institut für Physik, München, Germany j University of Iowa, Iowa City, IA 52242, USA

CERN experiment WA89 has studied charmed particles produced by a Sigma(-) beam at 340 GeV/c on nuclear targets. Production of particles which have light quarks in common with the beam is compared to production of those which do not. Considerable production asymmetries between D- and D+, D-s(-) and D-s(+) and A(c) and (A) over bar(c) are observed. The results are compared with pion beam data and with theoretical calculations.

CERN experiment WA89 has studied charmed particles produced by a Σ beam at 340GeV/c on nuclear targets. Production of particles which have light quarks in common with the beam is compared to production of those which do not. Considerable production asymmetries between D and D+, D−s and D + s and Λc and Λc are observed. The results are compared with pion beam data and with theoretical calculations. (Submitted to European Physical Journal C) aNow at TRIUMF, Vancouver, B.C., Canada V6T 2A3. bOn leave of absence from Moscow State University, 119889 Moscow, Russia. cNow at FNAL, PO Box 500, Batavia, IL 60510, USA. dNow at Fraunhofer Institut für Solarenergiesysteme, D-79100 Freiburg, Germany. eNow at Fakultät für Physik, Universität Freiburg, Germany. fNow at Institute for Cosmic Ray Research, University of Tokyo,Japan. gNow at Max-Planck-Institut für Physik, München, Germany hNow at Thomas Jefferson Lab, Newport News, VA 23606, USA. iUniversity of Iowa, Iowa City, IA 52242, USA. jNow at Technische Universitaät München, Garching, Germany kRutgers University, Piscataway, NJ 08854, USA. lpermanent address: CERN, CH-1211 Genève 23, Switzerland mNIKHEF,1009 DB Amsterdam, The Netherlands. nsupported by the UK PPARC. osupported by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie, Germany, under contract numbers 05 5HD15I, 06 HD524I and 06 MZ5265.

We report the first observation of the + decay mode of the 0(1690), confirming the existence of this resonance. The 0(1690) were produced by of 345GeV=c mean momentum in copper and carbon targets. The mass and width are close to those observe d earlier for the (1690) in the K decay channel. The product of inclusive production cross section and branching ratio is given relative to that of the 0(1530). (Submitted to Zeitschrift für Physik C) aNow at TRIUMF, Vancouver, B.C., Canada V6T 2A3. bOn leave of absence from Moscow State University, 119889 Mos cow, Russia. cNow at FNAL, PO Box 500, Batavia, IL 60510, USA. dNow at Fraunhofer Institut für Solarenergiesysteme, D-79 100 Freiburg, Germany. eNow at Fakultät für Physik, Universität Freiburg, German y. fNow at Institute for Cosmic Ray Research, University of Toky ,Japan. gNow at Thomas Jefferson Lab, Newport News, VA 23606, USA. hUniversity of Iowa, Iowa City, IA 52242, USA. iNIKHEF,1009 DB Amsterdam, The Netherlands. jsupported by the UK PPARC. ksupported by the Bundesministerium für Bildung, Wissensc haft, Forschung und Technologie, Germany, under contract numbers 05 5HD15I, 06 HD524I and 06 MZ5265.

We present the measurement of the lifetime of the Ωc0 we have performed using three independent data samples from two different decay modes. Using a Σ− beam of 340 GeVc we have obtained clean signals for the Ωc0 decaying i Ξ−K−π+π+ and Ω−π+π−π+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Ωc0 is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be τωc0 = 55−11+13(stat)−23+18(syst) fs. This makes the Ωc0 the shortest living weakly decaying particle observed so far. The short value of the lifetime comfirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.

Among the ground state charmed hadrons the Omega(c)(0) is the least known particle. It has so far been observed in a few decay channels only and with low statistics. Using a data sample of 1993 from the CERN hyperon beam experiment WA89 the Omega(c)(0) has been found in 7 decay modes which cover final states with Omega(-), Xi(-) and Lambda. We present a measurement of the Omega(c)(0) mass and its lifetime.

We present the measurement of the lifetime of the Ωc0 we have performed using three independent data samples from two different decay modes. Using a Σ− beam of 340 GeVc we have obtained clean signals for the Ωc0 decaying i Ξ−K−π+π+ and Ω−π+π−π+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Ωc0 is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be τωc0 = 55−11+13(stat)−23+18(syst) fs. This makes the Ωc0 the shortest living weakly decaying particle observed so far. The short value of the lifetime comfirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.

We present the measurement of the lifetime of the Omega_c we have performed using three independent data samples from two different decay modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Omega_c is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c the shortest living weakly decaying particle observed so far. The short value of the lifetime confirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.

Electron spin polarizations of about 8% were observed at HERA in November 1991. In runs during 1992, utilizing special orbit corrections, polarization values close to 60% have been achieved. In this paper the polarimeter, the machine conditions, the data analysis, the first results and plans for future measurements are described.