GALEPH, the detector simulation program of the ALEPH detector was ported to an ETA10 running under AT&T UNIX System 5. The program on the ETA10 can be driven using standard UNIX socket connections between the ETA and a Silicon Graphics Iris-3020 workstation. The simulated data on the ETA are transferred, using the machine independent binary format EPIO, and displayed on the workstation using a locally developed software package for the visualization of the ALEPH detector. The client (Iris-3020) can also pass parameters to the server (ETA10) and thus interactively change the type of events produced using the same socket connection.

A Monte Carlo code used for the detailed simulation of the response of the ALEPH time projection chamber has been successfully restructured to exploit the vector architectures of the CDC CYBER-205, ETA10 and CRAY X-MP supercomputers. Some aspects of the vector implementation are discussed and the performance on the various processors is compared.

The inclusive production of K0's and Λ's has been investigated in neutrino and antineutrino interactions in BEBC, filled with a neon-hydrogen mixture. The inclusive rates for the 3083 (1022) ν (ν) induced charged current events are (23.0 ± 1.7)% ((21.9 ± 2.8)%) for K0's and (5.7 ± 0.7)% ((6.5 ± 1.2)%) for Λ's. The general behaviour of the K0's and Λ's is found to be similar to that in νp interactions and π+p interactions at lower 〈W〉. In the hadronic c.m.s. K0's are produced mostly forwards, Λ's predominantly in the backward hemisphere. The data indicate that K0's produced in ν interactions on average carry a larger fraction of the total available momentum than those in ν induced reactions. The dependences of the average transverse momentum on the variables Q2, W2 and Bjorken x are presented.

The construction of a KL0 beam for the CERN 2 m hydrogen bubble chamber and the derivation of the beam momentum spectrum are described. Cross sections are presented for the reaction KL0+p → KS0+π++π−+p for KL0 momenta up to 17 GeV/c. The reacti is seen to be dominated, particularly at the highest momenta, where there are no previous data, by the production of the Q0-Q0 system. The shapes of the t-distributions for Q0 and Q0 prodcution are found to be different in a sense opposite to that expected from the pion-exchange Deck model. A model in which the observed effect is ascribed to the addition of a K∗ exchange Deck graph is found to be incompatible with the data. The data are, however, consistent with a model in which the Q0-Q0 system is largely resonant and the sense of the cross-over is determined by the s-channel quantum numbers.

The construction of a K L 0 beam for the CERN 2 m hydrogen bubble chamber and the derivation of the beam momentum spectrum are described. Cross sections are presented for the reaction K L 0 +p → K S 0 + π + + π − +p for K L 0 momenta up to 17 GeV/ c . The reacti is seen to be dominated, particularly at the highest momenta, where there are no previous data, by the production of the Q 0 - Q 0 system. The shapes of the t -distributions for Q 0 and Q 0 prodcution are found to be different in a sense opposite to that expected from the pion-exchange Deck model. A model in which the observed effect is ascribed to the addition of a K ∗ exchange Deck graph is found to be incompatible with the data. The data are, however, consistent with a model in which the Q 0 - Q 0 system is largely resonant and the sense of the cross-over is determined by the s -channel quantum numbers.

We have estimated cross sections for the production of resonances in the reactions K−p → Λ0 + pions. The data have also been analysed by a method which examines event-to-event fluctuations. Within the framework of the simple parametrization of resonance production assumed, the contribution from the resonances is insufficient to explain the observed fluctuations in the longitudinal emission of the final-state particles. These features are well reproduced by an independent cluster emission model.

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V0 topology of pp interactions at 12 GeV/c. The mass, widht and the product of cross section σI times the branching ratio BR into the final state (Ksoτ±τ+τ− are found to be: MI=2.60 ± 0.01 GeV/c2, ΓI⩽0.018 GeV/c2, σI·BR≈20 μbarn

It has been suggested that the (Kππ) enhancement observed near 1780 MeV, the L-meson, can be explained as a threshold enhancement in the K∗ (1420)π system. Here quantitative evidence is presented from 10 GeV/c K−p interactions to show that this is not so and that the L-enhancement must have decay modes other than K∗ (1420)π.

The five-point function Veneziano model has been applied to the reaction K−p → pK0π− in the energy range from ≈ 3 to 10 GeV/c. The predictions of the model are shown to be sensitive to the choices made for the assumptions and the parameters involved in the expression of the amplitude. Several choices can be made that give a satisfactory general description of this reaction. However, the mass spectra are not described in detail and the differential cross sections do not have the correct t-dependence, especially at the lower energies. These difficulties derive mostly from the fact that the simple model used does not consider the possibility that more than one trajectory is exchanged between a pair of particles.

The final states YKK + pions and Ξ−K + pions have been studied in K−p interactions at 10 GeV/c. The distributions of the c.m. longitudinal and transverse momenta of particles produced in channels of multiplicity 3 to 7 are discussed. The results are compared with the predictions of the multiperipheral Regge-pole exchange model.

Baryon states with strangeness S = −2 have been studied in 10 GeV/ c K − p interactions. The existence of the Ξ (2050) resonance is confirmed and also its decay into (Λ K π) is observed. Evidence is presented for a new Ξ state of mass 2500 MeV decaying into (Λ K π) , (σ K π), (Ξππ) and possibly into (Y K ). The possibility of there being a Ξ resonance near 2240 MeV is discussed.

Lambda production in 10 GeV/c K− interactions in hydrogen is studied. Cross sections are given for resonance production in quasi-two-body and many-body reactions, and their energy dependence is studied. It is found that the cross sections for quasi-two-body reactions requiring exchange of a strange meson decrease faster than that for the reaction K−p → pK∗−(890) which requires exchange of a non-strange meson. The cross section for Y∗−(1385) production decreases faster than that for Y∗+(1385) in quasi-two-body reactions. The distributions of the lambda c.m. production angle, transverse momentum and c.m. longitudinal momentum as a function of the particle multiplicity are studied.

Production of Ξ−, Ω− and antibaryons has been studied in 10 GeV/c K−p interactions. The Ξ∗(1530) is produced in about 15% of the reactions with Ξ− production. Four unambiguous examples of Ω− production with decay into (ΛK) have been observed: this gives a lower limit for the Ω− production cross section of 2.5 μb. One example of anti-Xi has been found. Distributions and average values of transverse and c.m. longitudinal momenta are presented.

K−p elastic scattering at 10 GeV/c is studied on ∼3600 bubble chamber events. The elastic cross section is found to be σel = (3.20 ± 0.14)mb and the ratio σelσtot = (0.142 ± 0.006), that is below the upper limit of 0.185 suggested in a model by Van Hove. The value of the forward differential cross section is consistent with zero real part to the scattering amplitude. The slope of dσdt is similar to that for π± and greater than that of K+, with no evidence for shrinkage of the diffraction peak. No events of backward scattering were observed. The Regge-pole model of Phillips and Rarita gives a good fit to the data.

Both in the reaction K-p→pK−π+π− and in the reaction K−p→pKoπ−πo induced by 10 GeV/c negative kaons on hydrogen, an enhancement is observed in the (Kππ)− effective mass distribution, at mass M = 1789 ± 10 MeV and with full width at half height Γ = 80 + 20−40 MeV. Evidence is presented which is consistent with the interpretation of this enhancement as a resonant state of isospin I = 12, with possible decay modes into Kπ, K∗π and Kω. It is proposed to name this resonance the L-meson.