G. Dehm

Production of K∗ (892) and K∗ (1420) in the reaction K+d→KπN(Ns) at 4.6 GeV/c

In a bubble-chamber experiment with the CERN 2 m chamber the reactions (i) K+d→K+π−pp, (ii) K+d→K0π0pp, and (iii) K+d→ K0π+ pn have been studied at a primary K+ momentum of 4.6 GeV/c. There is abundant production of K∗ (892) in reactions (i), (ii) and (iii), of K∗0(1420) in reactions (i) and (ii) and of Δ++ (1236) in reaction (iii). In reaction (i) backward production of K∗0 (892) is observed. Reaction and resonance-production cross sections are presented and their energy dependence is investigated. Production and decay angular distributions for the resonance bands are analyzed and compared to the results at other energies. In particular the data pertaining to the reaction K+n→K∗0p are compared in some detail with those for the reaction K−p→K∗0 (892) n. Finally, the evidence from reaction (i) for the existence of KN resonances other than K∗ (892) and K∗ (1420) is discussed.

Production of K∗(892) in K+N interactions at 3 GeV/c

We have studied the reactions K+d→K+π−pp,K+d→Koπopp,K+d→Koπ+pp, obtained from an exposure of the Saclay 81-cm bubble chamber filled with deuterium and exposed at CERN to a separated 3 GeV/c K+ beam. In reactions (1) and (2) there is abundant production of K∗0(892) and some production of K∗(1420). From the density matrix elements, it is found that K∗0(892) is produced mainly by pion exchange. The K∗(892) four-momentum-transfer distribution in reaction (1) agrees with the predictions of the OPE model, as modified by Durr and Pilkuhn. A marked asymmetry of the decay distribution of the K+π− system is observed and discussed in the framework of a unitarized Veneziano model. In reaction (3), on the other hand, the production of K∗+(892) and N∗+(1236) is found to proceed mainly by vector exchange.

The reaction K+d → Kopp at 4.6 GeV/c

Abstract In an experiment with the CERN 2m deuterium bubble chamber the reaction K+d→Kopp (1) and the related reaction K+n→Kop (2) are studied at an incident momentum of 4.6 GeV/c. The cross section for the latter reaction is found to be slightly larger than the cross section for the reaction K − p → K o n at the same energy. The corresponding differential cross sections agree within the rather large uncertainties. The forward amplitude for reaction (2) is predominantly real. Moreover, the total and forward differential charge exchange cross section values are compatible with those predicted on the basis of an SU (3) sum rule. A comparison of the K±-charge exchange differential cross sections with the predictions of a Regge pole model is also presented.

Study of K∗ o(892) δ++(1236) production from K+p interactions at 3 GeV/c

Abstract The reaction K + p → K ∗o (892) Δ ++ (1236) has been studied at 3 GeV/ c in both a hydrogen and a deuterium bubble chamber experiment. The production mechanism is described by a Regge-type model using π- and B-exchange. The joint decay distributions are analysed in various frames and compared with quark-model predictions.

Coherent K∗ production in K+d reactions at 3 GeV/c

Abstract In a study of K + d interactions at 3 GeV/ c we have observed the following reactions in which the deuteron does not break up: K + d → K o φ + d ( K o seen ) K + d → K + φ + φ − d An abundant production of K ∗ (892) is observed in these reactions. The production and decay angular distributions for K ∗ (892) are presented.

Production of the Kππ system in K+n and K+p interactions at 4.6 GeV/c

Abstract In an experiment with the CERN 2 m deuterium bubble chamber, the ( K ππ) 0 + systems in the effective-mass range below 1.5 GeV are studied for the reactions (1) K+n → K+π+π−n (2) K+n → K+π−π0n (3) K+n → K0π+π−n (4) K+p → K+π+π−n at 4.6 GeV/c incident momentum. Gross-section values are presented and the general features of these reactions are described. In addition the (Kππ)+ production and decay properties are investigated for reactions (1) and (4), and the results compared with the corresponding results for charge-exchange production of the (Kππ)0 system for reactions (2) and (3).

The reactions K+d → K+d, K+d → K+pn and K+d → K0pp at 3 Ge V/c with an investigation of K+n scattering

Abstract As a partial result of an analysis of K + d interactions at 3 GeV/ c produced in the 81 cm Saclay bubble chamber, we present data on K + differential cross sections for the following reactions: K + d → K + d, K + d → K + pn, K + d → K 0 pp . A set of parameters describing the K + n elastic scattering has been obtained from a simulataneous fit, based on the Glauber model. to the three experimental differential cross sections and to the K + d total cross section, giving α n = 1.7 ± 0.5 GeV −2 for the slope α n of the differential cross section, and ρ n = −0.16 ± 0.3 for the ratio of the real to the imaginary part of the forward scattering amplitude. The D-wave function of the deuteron has been found to give a non-negligible contribution to the coherent reaction.

Measurement of the reactions K+d → K+d and K+d → p+pn and an investigation of elastic K+-nucleon scattering at 4.6 GeV/c

Abstract The coherent elastic reaction K + d → K + d and the break-up reaction K + d → K + pn are studied in a K + d experiment at 4.6 GeV/ c which the CERN 2 m bubble chamber. Partial and differential cross sections are given and the slopes of the differential cross sections are determined. The results for the reaction K + d → K + p(n s ), where n s denotes the spectator neutron, are compared with those of the reaction K + p → K + p on free protons. Combining our data with existing data on the reactions K + d → K 0 pp and K + p → K + p, parameters of the elastic K + -nucleon scattering at 4.6 GeV/ c are determined in the framework of the Glauber model. The D-wave of the deuteron and spin-flip effects are taken into account.

Measurement of the reactions

Abstract The coherent elastic reaction K + d → K + d and the break-up reaction K + d → K + pn are studied in a K + d experiment at 4.6 GeV/ c which the CERN 2 m bubble chamber. Partial and differential cross sections are given and the slopes of the differential cross sections are determined. The results for the reaction K + d → K + p(n s ), where n s denotes the spectator neutron, are compared with those of the reaction K + p → K + p on free protons. Combining our data with existing data on the reactions K + d → K 0 pp and K + p → K + p, parameters of the elastic K + -nucleon scattering at 4.6 GeV/ c are determined in the framework of the Glauber model. The D-wave of the deuteron and spin-flip effects are taken into account.

K^+ d\to K^+ d

In an experiment with the CERN 2 metre bubble chamber, the reaction K+d→K+π+π−d has been studied at an incident K+ momentum of 4.6 GeV/c. The cross section is 250±30 μb. A strong K∗ (892) signal is seen and also a broad enhancement in the Q region (M(Kππ) < 1.5 GeV) with no evidence for narrow resonances in this mass interval. The production and decay properties of these objects are studied, and comparisons made with similar reactions on protons. The properties of the angular distributions of the Q decay are very similar to those found in the related reaction on a proton target. The spin-parity of the Q system is found to be predominantly 1+ although 2− cannot be excluded. The dπ mass distributions show an enhancement for mass values ∼2.2 GeV; however the marked asymmetry in the corresponding decay angular distribution argues against a resonance interpretation of this effect.