Philippe Peeters

Spin, branching ratios and production characteristics of the K∗(1420)

Abstract The reactions (1) K + p → K ∗ (1420) p and (2) K + p → K ∗ (1420) N ∗ (1236) are studied at 5 GeV/c incident K+ momentum. The simultaneous fitting of the K π and K ∗ (892)π decayy modes of the K∗ (1420) in the same production reaction makes it possible to eliminate 1− as the spin of the K∗(1420). The most likely K∗(1420) spin-parity assignment is 2+ although 3− cannot be excluded. The various decay branching ratios of the K∗(1420) are determined. The ratio of the K ∗ (892)π to the Kπ decay modes is found to be 0.9 ± 0.2. The peripheral production of the K∗(1420) seems to be due predominantly to vector-meson exchange in reaction (1) and to pion exchange in reaction (2).

Jet-like properties of multiparticle systems produced in K+p interactions at 70 GeV/c

Abstract We present results on the jet-like properties of multiparticle systems produced in K+p interactions at 70 GeV/c. The data analysed in terms of several variables commonly used to study the jet structure of an event. An extensive comparison is made with jets found in electron-positron annihilations and in deep inelastic νN interactions at comparable energy. Many similarities are found between low-pT jets in this experiment and jets observed in leptonic interactions. Our data are very well reproduced by the Field-Feynman quark fragmentation parametrisation but equally well by a longitudinal phase space model, suggesting that these similarities do not prove or disprove the universal character of the jet fragmentation.

Evidence for three Kππ resonant states below 1.4 GeV in K+p reactions at 5 GeV/c

Abstract The study of K+p reactions at an incident momentum of 4.97 GeV/c suggests that the wide enhancement in the (Kππ)+ mass spectrum may be split into several resonant states. In particular, examination of the K ∗ (892)π decay mode indicates the existence of the states K∗(1230), K∗(1280) and K∗(1320), in addition to the well known K∗(1420). The K∗(1230) and K∗(1320) have the properties expected from 1+ states produced by 0+ exchange.

Disseminated African histoplasmosis in a white heterosexual male patient with the acquired immune deficiency syndrome.

Summary: Disseminated African histoplasmosis was diagnosed in January 1986 in a 38‐year‐old white heterosexual male. The patient, who had been living in Zaire from 1972 until 1978, had serological evidence of AIDS. He was successfully treated with amphotericin B followed by oral ketoconazole.

Study of multi-body final states in K+p reactions at an incident momentum of 5 GeV/c

Abstract Results are given on the comparison of the predictions of the multiperipheral model of Chan, Loskiewicz and allison with the experimental data obtained from a study of the interactions of 5 GeV/c K+ mesons with protons. Comparisons have been made in the three-, four-, five- and six-body final states containing a proton, kaon and pions. With the addition of resonance production to the model, adequate predictions of experimental distributions are obtained. An attempt is made to describe the energy variation of the three- and four-body final-state cross sections.

Study of the reaction K+p→ K*0 (890) Δ++ from 4.6-16.0 GeV/c

Abstract A systematic analysis is presented on the reaction K + p → K ∗0 (890) Δ ++ for nine incident momenta between 4.6–16.0 GeV/ c . Cross sections, differential cross sections and vector meson single density matrix elements are given. As a function of energy, little if any change is observed in either the shapes of the differential cross sections or in the values of the density matrix elements. The data are interpreted in terms of current ideas on t -channel exchange mechanisms.

Nonlinear transport processes in tokamak plasmas. I. The collisional regimes

An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear (“Onsager”) transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch–Schluter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for Joint European Torus (JET) plasmas are also reported. It is found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor that may be of the order 102. The nonlinear classical coefficients exceed the neoclassical ones by a factor that may be of order 2. For JET, the discrepancy between experimental and theoretical results for the electron los...

Inclusive Δ++ production in K+p interactions at 8.2 and 16 GeV/c

Abstract The reaction K + p→ Δ ++ (1236)+ anything is studied at beam momenta 8.2 and 16 GeV/ c and compared with other Δ ++ producing reactions. We find that the low-mass Δ ++ π − enhancement affects the shapes of Δ ++ inclusive distributions. The triple-Regge formula is found to be consistent with the data. Dual properties of this formula are successfully tested.

Influence of random initial conditions on explosive systems

It has been shown that the exothermal and isothermal explosive systems are extremely sensitive to fluctuations of either thermodynamical and environmental origin as well as to the way they are initially prepared. The latter source of variability, manifested through small differences in initial conditions, can deeply affect the transient behavior. Applied to an exothermic explosive model, like the Semenov model, the effects of random initial conditions manifest themselves in a wide dispersion of explosion times. Furthermore, under certain conditions the distribution of explosion times becomes bimodal: the initial set of systems split, with the same probability, into a short explosion time class and a long explosion time class.

Study of the exchange mechanism in K+p → K+π-N*++ at 5 GeV/c incoming K+ momentum

We present results on the analysis of the quasi three-body reaction K+p → K+π-N*++ obtained from bubble chamber exposures at 5 GeV/c incident K+ momentum. We have applied a method of analysis based on the study of the longitudinal phase space plot recently proposed by Van Hove. Evidence for the existence of π- mesons with a four-momentum transfer peaked at small values is shown. (Events contributing to this peak correspond to the cross section of about 80 μb.) The difficulties in explaining this result in terms of the double-particle exchange model are discussed.