The inclusive production of Ks0, Λ, Λ¯, and Ks0Λ in the p¯Ta reaction at 4 GeV/c was measured and compared with that in the p¯p reaction. The total inelastic and topological cross sections were also measured. The number of Λ’s produced in the p¯Ta reaction was 11.3 times larger than that expected from the geometrical cross section, which is defined as A2/3 times the cross section for the p¯p reaction. The yield ratio Λ¯/Λ was found to be 2×10−2. These values cannot be accounted for by a straightforward extension of the p¯N reaction. Besides, a correlation of 2 vees like Ks0-Λ could not prove their simultaneous production. Nuclear temperatures of 135 and 97 MeV were obtained from the kinetic energy spectra of Ks0 and Λ, respectively. The kinematical characteristics of the Ks0 and Λ produced were analyzed in terms of the fireball model.
The reactions K − d→ Σ − p, K − d→ Σ − (1385)p, K − d→ Λ (1405)n and K − d→ Λ (1520)n have been studied at K − momenta between 686 and 844 MeV/ c in an experiment with the 81 cm Saclay bubble chamber at CERN. About 630 000 pictures have been analyzed. Partial and differential cross sections are presented. A one-nucleon-exchange model is used to extract the kaon-nucleon-hyperon coupling constants from these results. For g( K N Σ(1197)), g( K N Σ(1385)) and g( K N Λ(1405)) we find values which are compatible with the SU(3) predictions. The coupling constant g( K N Λ(1520)) obtained by our method agrees with that determined from the partial decay width for Λ(1520)→ K N .
Differential cross sections and polarizations have been measured for the reaction π − p → K 0 Λ and π − p → K 0 Σ 0 at 3.9 GeV/ c π − momentum. Comparison of these data with those of the related reactions K − n → π − Λ and K − p → π − Σ + (at approximately the same c.m. energy) indicate that simple Regge-pole models involving only K ∗ (890) and K ∗ (1420) exchange are unable to describe all the features of the data. On the other hand, comparison of the π − p → K 0 Σ 0 data with that of π + p → K + Σ + shows that the data are consistent with absence of exotic strange-meson exchange.
Final data on topological cross sections are presented. Inclusive single particle distributions for the reactionsK+p→ π±X at 32 GeV/c are discussed and compared with data at lower energies. Early scaling in the fragmentation regions is confirmed, while cross sections in th central region continue to rise with energy even faster than inpp interactions. Thex-andpT-dependence of the π+/π− ratio inK+p interactions is discussed and a comparison of reactionsK+p→ π±X andK−p→ π±X at 32 GeV/c is made in the context of constituent models. We also present transverse momentum distributions, show prominent seagull effects and study how they are influenced by resonance production.
The differential cross sections for Bhabha scattering and μ pair production, and the total τ pair cross section as measured by the PLUTO detector at PETRA, have been analyzed to extract information on the weak interaction of leptons. The data are compared with unified gauge theories. Since the observed electroweak effects are still consistent with zero (within errors) we can set experimental limits on neutral current parameters atQ2 values of 950 GeV2. In the framework of the standard SU(2)×U(1) model we find sin2Θw<0.52(95% c.l.). In the context of general singleZo models we can excludeZo masses of less than 40 GeV.
The differential cross sections for K+d coherent, breakup, and charge-exchange scattering have been measured at several momenta in the interval 250-600 MeV/c. The data have been fitted using a partial-wave analysis. Assuming an s-wave description of I=1 scattering and using data from the coherent and charge-exchange channels, a description of I=0 K+−N scattering by a combination of s and p waves in a simple single-scattering impulse model has been attempted. The phase shifts obtained are unique up to the Fermi-Yang ambiguity, which can be removed by using existing polarization results at 600 MeV/c.
We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as $A^(alpha)$ where $\alpha$ is $0.46\pm0.06$ for a beam momentum of 58 GeV/c and 0.54$\pm$0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo.
The charge-exchange cross sections were measured for π − on Li, C, Al and Cu nuclei at momentum 48 GeV/ c . By comparing the data obtained for nuclei with those for hydrogen under the same conditions the effective numbers of protons are defined. The conclusion is made that η 0 mesons are absorbed in nuclei weaker then π 0 . The total cross section of η 0 interactions with the nucleon is determined to be σ tot ( η 0 N) = 15 ± 5 mb in agre ement with the quark model.
We have measured the total and differential cross-sections for coherently photoproduced ϱ, ω and ϱ′ on deuterium at 7.5 GeV. Using VDM relations, we have obtained γ ω 2 / γ ϱ 2 = 7.1 ± 1.5, σ T ( ϱ d) = (54 ± 2) mb and σ T ( ω d) = (56 ± 5) mb. Assuming the amplitude for ϱ′ production via an intermediate ϱ 0 to be small and that the amplitudes for ϱp and ϱ′p elastic scattering are comparable, we found γ ϱ ′ 2 / γ ϱ 2 = 6.0 ± 1.2 and σ T ( ϱ ′d) = (47 ± 6) mb.
We have studied high transverse momentum J/ψ production in p p interactions at s =630 GeV . The measured cross section times branching fraction for J/ψ→μ + μ − production with p T ⩾5 GeV / c and | y |<2.0 is 7.5±0.7±1.2 nb . The event topology is used to establish that there is J/ψ production from both the direct production of c c bound states and the decay of B hadrons. The inferred yield of J/ψ from beauty decays is compatible with our estimates of beauty production in other channels.
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