J.M. Gago

Inclusive K∗−(890) and K∗0(890) production in 14.3 GeV/c K−p interactions

Results on the inclusive reactions K−p → K∗−(890) + X+ and K−p → K∗0 (890) + X0 at 14.3 GeV/c are presented. A comparison is made with previous data and with the reaction K−p → K0 + X at 14.3 GeV/c. Predictions of a triple-Regge model for the variation of the unnatural and natural parity exchanges with the mass of the X system are examined. The experimental values of the structure functions are compared with those calculated from a quark model.

Inclusive production of charged and neutral sigma hyperons in K−p interactions at 14.3 GeV/c

Abstract Inclusive production of Σ + , Σ − and Σ 0 hyperons in K − p interactions at 14.3 GeV/ c has been studied and compared to Λ production. Cross sections are presented as a function of longitudinal and transverse momenta and compared to the pp → Σ + + anything data.

Inclusive production of Y∗ resonances in K−p interactions at 14.3 GeV/c

The inclusive production of Σ+(1385), Σ−(1385), Λ(1405) and Λ(1523) in K−p interactions at 14.3 GeV/c is studied. Cross sections are presented and the x dependence of the invariant cross sections is discussed. The density matrices for production of the spin-32 resonances at small momentum transfer to the target are consistent with spin-0 exchange.

K−p elastic scattering at 14.3 GeV/c

Results are presented on elastic scattering of 10.1 GeV/c K− mesons on protons, based on a sample of 16 261 kinematically-fitted bubble-chamber events. The differential cross section is given over the |t|- range of 0.06 to 2.5 GeV2 and is fitted with the expressions a ebt, A eBt+Ct2 and (P eQt+ReSt) over various intervals of t. The results are compared with those of other experiments at nearby energies. Upper limits of |α| < 0.28 and σB < 0.4 μb (both at a 90% confidence level) are given for the ratio of real to imaginary part of the forward-scattering amplitude and the backward-elastic-scattering cross section, respectively.

New evidence for K∗ (1780) production

Abstract We present the first evidence for K ∗ (1780) production in a non-exchange channel. This comes from a study of the reaction K − p → K° π − p at 14.3 GeV/ c . We also present evidence for K ∗ ° (1780) production in the charge exchange channel K − p → K − π + n. No significant K ππ , K ω and K η decay modes are found. The decay angular distribution, the spin-parity assignments and the production mechanism are discussed. With plausible assumptions on the production mechanism, the J P = 3 − spin-parity is favoured.

Lambda polarization in the reaction K−p → Λ + anything at 14.3 GeV/c

New results on inclusive lambda polarization in K−p interactions at 14.3 GeV/c are presented. At the kaon fragmentation vertex, the polarization is compared to that from inclusive experiments at lower momenta and to that from two-body reactions with a Λ. As predicted by the triple-Regge model with Nα (or Nγ) exchange, the polarization is found to be independent of s and MX2/s. In particular it has the same value as that found in the two-body reactions.

Some three-body final states in K−p reactions at 14.3 GeV/c

We present experimental results on a number of K−p reactions at 14.3 GeV/c that have three bodies in the final state. The final states are K−ωp, K−πp, Λπ+π−, ΛK+K−, Λpp, K∗−ωp, Λ(1520)K+K− and Λ(1520) pp. Whenever, with one exception explained by the Zweig rule, there is a K− or a proton in the final state, there is a diffractive-like threshold enhancement in the mass spectrum of the two recoiling particles. These enhancements account for a large fraction of the events in all but the Λπ+π− final state, where they cannot occur, and which is dominated by resonance production. We find evidence for the Q1(1300) decaying into K−ω.

Inclusive γ production in K− p interactions at 14.3 GeV/c

Abstract Results are presented on γ production in K− p interactions at 14.3 GeV/c. The analysis is based on 2 541 fitted e+e− pairs in a hydrogen bubble chamber. The inclusive cross section for γ production is found to be (54.5 ± 1.8) mb. The average number of γs per inelastic event is 2.93 ± 0.12; it exhibits no strong dependence on charged multiplicity. From the PL and PT2 invariant distributions of the γ, a simple function describing the π° invariant distribution is determined.

Inclusive pion and eta production in K−p interactions at 14.3 GeV/c

Abstract The inclusive cross sections for π − , π 0 , π + and η production in K − p interactions at 14.3 GeV/ c are calculated. The invariant cross section distributions are presented and compared in the whole phase space for π + and π 0 , and in the backward c.m. region for π − . In the fragmentation regions, the charged pion production is analysed in terms of the triple-Regge model.

The inclusive reaction K− p → pX at 14.3 GeV/c

Abstract We have measured the reaction K − p → pX at 14.3 GeV/ c , in the fragmentation region of the target proton. The differential cross section is studied as a function of momentum transfer and missing mass squared. In the triple-Regge limit, it is consistent with the dominance of a MMP coupling at large t but it is possible that couplings of the type PPP and ππ P also contribute at small | t | values.