Hyperon-antihyperon production in pp interactions at 3.6 GeV/c leading to ⩾3 particles in the final state

Results are presented on the properties of the $\text{p}$p interactions at 3.6 GeV/c leading to a hyperon or an antihyperon in final states with ?3 particles from an experiment of 35 eV/μb sensitivity. Results of amultidimensional mass fit to each final state are given along with the cross sections, differential cross sections and polarization, where possible, for the hypercharge exchange reactions $\text{p}\text{p}\text{→}\text{Λ}\text{Y}{}^1\text{(1385),}\text{Λ}\text{Y}{}^1\text{(1520),}\text{Σ}\text{Y}{}^1\text{(1385)}\text{and}\text{Σ}\text{Y}{}^1\text{(1520)}$.     

The reactions K−p → π∓Σ± at 4.2 GeV/c

We present differential cross sections and the Σ⁺ polarization for the reactions K^?p → π^?Σ^± using data from a high statistics bubble chamber experiment at 4.2 GeV/c incident momentum. The statistical level allows a detailed analysis of these reactions over the whole t range. Several significant structures are observed. Comparisons are made with SU(3)-related reactions; for backward production of π^?Σ⁺ such a comparison shows good evidence for Δ exchange. The exotic forward peak in K^?p → π⁺Σ^? is definitely confirmed.     

Non-strange vector meson production in K−p interactions at 4.2 GeV/c

The vector meson production, hypercharge exchange reactions K^?p → (φ, ω, ?) Λ and (φ, ?) Σ⁰ are studied at 4.2 GeV/c incident momentum. The data come from a high statistics bubble chamber experiment with a sensitivity of ～ 120 events/μb. Total and differential cross sections are presented. The vector meson density matrix elements and hyperon polarization are investigated as functions of momentum transfer. Amplitude analyses are performed for all five reactions. The results are compared with duality and quark model predictions, as well as used to test current ideas in two-body phenomenology.     

Measurement of the τ lifetime

Using the 3-prong decays of τ leptons observed at the CELLO detector at PETRA, the τ lifetime is determined to be 4.7(_?2.9^+3.9)×10^?13s.     

Test of nuclear effects in hadronic dimuon production

We present the final analysis of the nuclear effects on the cross section of dimuon production, using simultaneously a hydrogen and a platinum target in a 150, 200 and 280 GeV pion beam. For the dimuon mass interval 4.1 to 8.5 GeV, the ratio of the cross sections is in agreement with the Drell-Yan model within a 10% error, mainly due to systematics. The variation of this ratio with the dimuon mass, x₁ and x₂ is also in good agreement, and no variation with the transverse momentum is observed.     

The four-momentum transfer distribution for the deuteron break up at 3.3 GeV/c incident deuteron momentum

The differential cross section (dσ/dt) for the dp → ppn charge retention reaction at 3.3 GeV/c deuteron momentum is studied and compared with the Glauber multiple scattering theory. Within the limits of the uncertainties of the existing elementary nucleon-nucleon data, the simple Glauber model calculations give, in general, a fair agreement with experiment, except for the low |t| region where possible spin effects may play a role.     

Study of the low-mass diffractive system produced in pp collisions at 12 and 24 GeV/c

We present an analysis of the decay of the low-mass diffractive system X produced in the reaction pp → p + X at 12 and 24 GeV/c. The various decay channels of the system have been separated; the decay multiplicity distribution is investigated and compared with the expectations of a two-step picture of diffraction dissociation. A comparison of virtual $\text{P}$_p with on-shell γp and pp processes is discussed.