G.F. Wolters

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

Abstract The vector meson production, hypercharge exchange reactions K − p → ( φ , ω , ϱ ) Λ and ( φ , ϱ ) Σ 0 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.

A partial-wave analysis of the 3π system in the reaction K−p → π+π−π0 Λ at 4.2 GeV/c

A partial-wave analysis of the (3π)0 system produced peripherally in the reaction K−p → π+π−π0 Λ at 4.2 GeV/c is presented. The observation of the weak Λ decay allows a determination of all the transversity production amplitudes except for two phases. The production of known resonances having decay modes other than 3π is used to test the isobar model ansatz. Significant ω(783), φ(1020) and A2(1310) production is observed. The spin parity of the ω∗(1675) is established as 3−. No evidence for production of other resonances, such as axial vector-mesons, is found.

Study of hypercharge exchange reactions of the type K−p → 1−32± at 4.2 GeV/c

Abstract Results are presented for the quasi two-body hypercharge exchange reactions of the type using data from a high statistics bubble chamber experiment. Total and differential cross sections and the momentum transfer dependence of the meson and hyperon resonance single density matrix elements are discussed. Amplitude analyses are performed for the first two reactions. The results are compared with quark model and duality predictions and with those from other related reactions.

Lambda production in the fragmentation processes p→K− and K− →p Λ at 4.25 GeV/c

Abstract In the reaction K − +p→ Λ +X at 4.25 GeV/ c both the target fragmentation of the proton into lambda and the beam fragmentation of kaon into lambda have been studied. The sample consists of 21 000 Λ events with t >−1.0 (GeV/ c ) 2 and 9000 Λ events with u > −1.0 (GeV/ c ) 2 . Abundant π 0 and meson resonance production for residual masses M x c 2 is observed. In the t -channel of am effective exchange trajectory is deduced. which lies between the K and K(890) trajectories. In the u -channel the effective exchange trajectory is in good agreement with a nucleon trajectory. The extrapolated average pion multiplicities of the residual mass system in the t -channel are in very good agreement with the values measured in antiproton-proton annihilations at rest.

Study of Σ±(1385) inclusive production in K−p interactions at 4.2 GeV/c

Abstract Properties of Σ ± (1385) inclusively produced in 4.2 GeV/ c K − p interactions are studied. Inclusive cross sections are presented together with differential cross sections as functions of x and p t 2 for both Σ + (1385) and Σ − (1385). The complete density matrix for Σ + (1385) production at small momentum transfer is studied as a function of t and of recoil mass MM 2 . Substantial agreement with the predictions of the additive quark model is found. The Σ + (1385) production in the target fragmentation region is studied in the framework of the triple-Regge model.

Spin-parity structure of the (Kππ)0 system produced in the charge-exchange reaction K−p → (K0π+π−)n at 4.2 GeVc

Abstract A partial wave analysis of the K 0 π + π − system produced in the charge exchange reaction K − p → ( K 0 π + π − ) n at 4.2 GeV/ c has been performed both as a function of Kππ mass and of t ′. The 1 + S wave forms the largest contribution to the K ππ system and peaks at roughly the same mass as the Q in diffractive K ππ production. The polarization properties of the 1 + S ( K ∗ π) and 1 + S (Kϱ) waves differ fromt those of the diffractive 1 + wave. There is some evidence for a resonance contribution to 1 + S ( K ∗ π) . The strong 2 + wave the K ∗ (1420) and the K ϱ/ K ∗ ϱ decay branching ratio determined to be 0.36±0.10. An enhancement with spin-parity 1 − is observed under K ∗ (1420) .

Spin Parity Structure of the (anti-K pi pi)0 System Produced in the Charge Exchange Reaction K- p --> (anti-K0 pi+ pi-) n at 4.2-GeV/c

Abstract A partial wave analysis of the K 0 π + π − system produced in the charge exchange reaction K − p → ( K 0 π + π − ) n at 4.2 GeV/ c has been performed both as a function of Kππ mass and of t ′. The 1 + S wave forms the largest contribution to the K ππ system and peaks at roughly the same mass as the Q in diffractive K ππ production. The polarization properties of the 1 + S ( K ∗ π) and 1 + S (Kϱ) waves differ fromt those of the diffractive 1 + wave. There is some evidence for a resonance contribution to 1 + S ( K ∗ π) . The strong 2 + wave the K ∗ (1420) and the K ϱ/ K ∗ ϱ decay branching ratio determined to be 0.36±0.10. An enhancement with spin-parity 1 − is observed under K ∗ (1420) .

On quark model relations for hypercharge-exchange reactions

Peripheral two-body reactions of the type K−p→M0 + Λ, Σ0 or Σ0 (1385) are considered. Predictions based on the additive quark model and SU(6) baryon wave functions are tested against data on cross sections and polarisations for given momentum transfer. Data obtained in a high statistics experiment at 4.2 GeV/c K− momentum, as well as data from a large variety of other experiments are used. Highly significant violations of these predictions are observed in the data. These violations are shown to occur in a systematic fashion, according to which SU(6) must be relaxed, but the amplitude structure implied by additivity would remain valid. As an application an amplitude analysis for natural parity exchange reactions with M0 = π, ϕ and ϱ respectively is performed, which determines a relative phase, which cannot be obtained in a model-independent analysis. Also reactions with M0 = δ or B are considered, and some implications for coupling constants are discussed.

A study of inclusive Ξ− production from K−p interactions at 4.2 GeV/c

A study of inclusive Ξ− production from a high statistics K−p experiment at 4.2 GeV/c has been made. The total Ξ− production cross section is 157 ± 8 μb. Approximately 15% of the Ξ− arise from decay of the Ξ∗0(1530) resonance. The polarization of the Ξ− is found to be negative and is nearly equal in value to that of the Λ0 from the inclusive reaction K− + p → Λ0 + anything. An analysis of the inclusive production of Ξ− has been made in the framework of the triple-Reege formalism.

SU(3) implications of the observation of the A1 and C mesons

Abstract A new determination of the Q A −Q B mixing angle and of the antisymmetric coupling for the vector-pseudoscalar decay of the axial vector mesons is presented. This uses information from the decay rates of the A 1 and C mesons found in the study of baryon exchange processes in K − p interactions at 4.2 GeV/ c combined with the decay rate B → ωπ . The consistency between the results obtained from backward produced A 1 and C and diffractively produced Q 1 and Q 2 is discussed.