Search

The low-mass (Kππ) system of the reaction K-p → K-pπ+π- at 8.25 GeV/c is studied. The cross-section of this reaction is (0.97± ±0.04) mb. The dependence of the cross-section on the proton-proton momentum transfer shows broadening of the diffraction peak with respect to increasing (Kππ) mass. The production of two-body and three-body resonances is discussed with respect to their occurrence in the four longitudinal-momentum phase space sectors of pl(π+)vs. pl(π-). This allows to separate the three-body low-mass systems (Kππ) and (pππ), which can be produced diffractively, from the other quasi-two-body processes whose production mechanism is meson exchange. In order to discuss what spin-parity contributions can be distinguished in the lowmass (Kππ) system, the D-moments of the angular distributions of the (Kππ) system with respect to variation of its effective mass and to variation of the possible analyser directions are carried out. The result is that, in addition to the dominant JP=1+ content, there is a clearly identifiable JP=0- contribution to the low-mass (Kππ) system. This contribution can be estimated to be 10% by an analysis of the density of events in the Dalitz plot, which gives also that the ρ production amplitude with respect to the K*(890) production amplitude decreases with increasing (Kππ) mass. This result is in agreement with an analysis of the reaction K+p→ K+pπ+π-. In the Appendix are given the properties of the D-moments and their predictability or suppression with respect to various spin-parity contributions. © 1974 Società Italiana di Fisica.

The final state K-ωp shows no significant resonance production at 8.25 GeV/c. A double moments analysis of the broad threshold (K-ω) enhancement shows the presence of 0-, 1+ and 1- spin-parity states. The last one was foundto contribute about 10% (while we were unable to separate the contributions from 1+ and 1-. An analysis of the final state in terms of the CLA model shows qualitative agreement with the data. Moreover, using the same parameters, the predicted distributions at 6 and 10 GeV/c show the same qualitative agreement with the published data. © 1974.

A model for the reactions Kp → Qp is given assuming dominance of pomeron and ω, f exchanges. The coupling of the pomeron is taken in accord with s-channel helicity conservation (SCHC) and both real and imaginary parts of the SCH amplitudes for ω and f exchange have a t-structure in accord with amplitude analyses. The model was fitted to the 8.2 GeV/c K-p and 7-9 GeV/c K+p data and is seen to describe satisfactory the dσ/dt and (dσ/dt) ρ{variant}ij distributions. A cross-over is predicted at {norm of matrix}t′{norm of matrix} = 0.18±0.03 which is consistent with experimental data. The energy dependence of the cross section predicted for 4 < Plab ≤ 14 GeV/c is in good agreement with experimental data K+ and K0. The model predictions concerning s- and t-channel helicity conservation are in good agreement with current experimental data while the model predicts that for beam momenta higher than 30 GeV/c, SCHC should be apparent in all the reactions K± → Q±p, K0p → Q0p andK0p → →Q0p. © 1974.

The reaction K-p→Q-p→p(K-K-π+π-) at 8.25 GeV/c favours t-channel helicity conservation over s-channel helicity conservation. This is shown by comparing the Q density matrix elements with the predictions of the above two hypothesis as functions of the crossing angle. © 1971.

Using data from our K-p experiment at 8.25 GeV/c we have investigated the charged particle multiplicity, and the variation of charged pion multiplicity as a function of the effective mass squared of all pions, for various samples of data, and compared our results with pp annihilation data and pp data. Evidence is presented which suggests that the difference in behaviour between the annihilation and non-annihilation data is not due to some specific mechanism such as baryon exchange, but is related to the absence of leading particles in the former case. © 1973.

Topological and channel cross sections are given for the more common final states produced in K-p interactions at 8.25 GeV/c together with the single particle inclusive cross sections. We present cross sections for prominent resonances occurring in final states KN (nπ) and find the resonance fractions to be roughly independent of multiplicity. © 1973.

We present double differential cross sections for the reactions K- + p → π± + anything at 8.25 GeV/c. Using published data for reactions K+ + p→ π- + anything and p + p → π+ anything we predict the differential cross sections for γ + p → π- + anything, π- + p → π- + anything and π- + p → π+ + anything in the target fragmentation region based on factorisation of the pomeron and Regge trajectories. Our predictions agree with the experimental data and support the hypothesis of factorisation of the Regge trajectories in the target fragmentation region. © 1973.

A variation of the model proposed by Plahte and Roberts is used to fit data from the reaction K-p → K0π-p at 8.25 GeV/c. The channel K-p → K*-p is also studied in some detail and the energy dependence of the cross section is discussed. The behaviour of the differential cross sections and of the density matrix elements of K* in the G-J frame as function of t' suggests dominance of vector exchange with a small π-exchange contribution. The density matrix elements are also given in the helicity fram and a fit to the Harari model supports the dominance of natural-parity exchange and of the helicity non-flip amplitude at the nucleon vertex. © 1973.